konhon

忘掉過去,展望未來。找回自我,超越自我。
逃避不一定躲的过, 面对不一定最难过, 孤单不一定不快乐, 得到不一定能长久, 失去不一定不再拥有, 可能因为某个理由而伤心难过, 但我却能找个理由让自己快乐.

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以下问题是这一期间回答waterlily 关于java的一些整理,发现对大家都很有作用,现在将这些详细讲解的程序单独列出来供大家参考,学习,讨论

------------------------------------------------------------
1.使用jdbc连接数据库--通过jdbc连接数据库,将SQL语句运行结果打印到控制台

package ConnectionTest;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.Statement;

public class ContactTest {        
        
private Connection conn = null;
        
        
public void getConnection(){
                
try{
                        String JDBC_URL 
= "jdbc:pointbase:server://localhost:9092/test";
                        String JDBC_DRIVER
="com.pointbase.jdbc.jdbcUniversalDriver";                                        
                        String USER 
= "PBPUBLIC";
                        String PASSWORD 
= "PBPUBLIC";
                        
                        Class.forName(JDBC_DRIVER).newInstance();
                        conn 
= DriverManager.getConnection(JDBC_URL,USER,PASSWORD);
                        System.out.println(
"connection success");
                }
catch(Exception e){
                        e.printStackTrace();
                }

        }

        
        
public void excute(){
                
                
try{
                        Statement stmt  
= this.conn.createStatement();
                        String SQL 
= "select id ,name ,age ,address  from test";
                        ResultSet rs 
= stmt.executeQuery(SQL);

                        ResultSetMetaData ss 
= rs.getMetaData();
                                
                        
int count = ss.getColumnCount();

                        
for(int j = 1; j <= count; j++){
                                System.out.print(ss.getColumnName(j)
+"        ");
                        }

                        System.out.println(
" ");
                        
                        
while(rs.next()){        
                                
for (int i = 1; i <= count;i++){
                                        System.out.print(rs.getString(i)
+" ");
                                }

                                System.out.println(
" ");
                        }
 
                        rs.close();
                        stmt.close();
                        
this.conn.close();                       
                }
catch(Exception e){
                        e.printStackTrace();
                }

                
        }

        
        
public static void main(String[] args) 
        
{
                ContactTest  ct 
= new ContactTest ();
                ct.getConnection();
                ct.excute();
        }

        
}

------------------------------------------------------------ 2.在上题基础上增加对文件的操作--将从数据库得到的信息选择性的放到不同的txt文件中
package ConnectionTest;

import java.io.BufferedWriter;
import java.io.File;
import java.io.FileWriter;
import java.io.IOException;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Iterator;

public class ContactTest {        
        
private Connection conn = null;
        
private int flag;
        
        
        
        
public void getConnection(){
                
try{
                        String JDBC_URL 
= "jdbc:pointbase:server://localhost:9092/test";
                        String JDBC_DRIVER
="com.pointbase.jdbc.jdbcUniversalDriver";                                        
                        String USER 
= "PBPUBLIC";
                        String PASSWORD 
= "PBPUBLIC";
                        
                        Class.forName(JDBC_DRIVER).newInstance();
                        conn 
= DriverManager.getConnection(JDBC_URL,USER,PASSWORD);
                        System.out.println(
"connection success");
                }
catch(Exception e){
                        e.printStackTrace();
                }

        }

        
        
public void closeConnection() throws SQLException{
                
if(this.conn != null){
                        conn.close();
                }

        }

        
        
public void getResult(int flag,Collection col) throws IOException{
                String name 
= null;
                
if(flag == 0){
                        System.out.println(
"输出查询信息");
                        name 
= "select.txt";
                        WriterOut(name,col);
                }
else if(flag == 1){
                        System.out.println(
"输出插入信息");
                        name 
= "insert.txt";
                        WriterOut(name,col);
                }
else if(flag == 2){
                        System.out.println(
"输出修改信息");
                        name 
= "update.txt";
                        WriterOut(name,col);
                }
else if(flag == 3){
                        System.out.println(
"输出删除信息");
                        name 
= "delete.txt";
                        WriterOut(name,col);
                }
else{
                        System.out.println(
"标志码输入错误");
                }

        }

        
        
public void WriterOut(String name,Collection list) throws IOException{
                String path 
= "d:/"+name;
                File newFile 
= new File(path);  //这里注意你的输入文件的路径
                BufferedWriter wirter = new BufferedWriter(new FileWriter(newFile));
                
                Iterator it 
= list.iterator();
                
while(it.hasNext()){
                        String temp 
= (String)it.next();
                        System.out.println(temp);
                        wirter.newLine();
                        wirter.write(temp);
                        wirter.flush();
                }

                wirter.close();
                
        }

        
        
public void SelectDB(){
                
try{
                        getConnection();
                        Statement stmt  
= this.conn.createStatement();
                        String SQL 
= "select id ,name ,age ,address  from test";
                        ResultSet rs 
= stmt.executeQuery(SQL);
                        
                        Collection col 
= new ArrayList(); 
                        
                        ResultSetMetaData ss 
= rs.getMetaData();        
                        
int count = ss.getColumnCount();

                        String temp 
= "";
                        
for(int j = 1; j <= count; j++){
                                System.out.print(ss.getColumnName(j)
+"        ");
                                temp 
= temp + ss.getColumnName(j)+"              ";
                        }

                        col.add(temp);
                        
                        System.out.println(
" ");
                        
                        
while(rs.next()){        
                                temp 
= "";
                                
for (int i = 1; i <= count;i++){
                                        System.out.print(rs.getString(i)
+" ");
                                        temp 
= temp + rs.getString(i)+"       ";                
                                }

                                col.add(temp);   
//
                                System.out.println(" ");
                        }

                        getResult(
0,col);
                        rs.close();
                        closeConnection();
                }
catch(Exception e){
                        e.printStackTrace();
                }

        }

        
        
public void InsertDB(){
                
try{
                        getConnection();
                        String SQL 
= "insert into test values('0011','sandy','25','shanghai')";
                        PreparedStatement pstmt  
= this.conn.prepareStatement(SQL);
                        
                        ResultSet rs 
= pstmt.executeQuery();
                        
this.conn.commit();
                        
                        SQL 
= "select id ,name ,age ,address  from test";
                        Statement stmt 
= this.conn.createStatement();
                        rs 
= stmt.executeQuery(SQL);
                        ResultSetMetaData ss 
= rs.getMetaData();        
                        
int count = ss.getColumnCount();
                        
                        Collection col 
= new ArrayList();
                        
                        String temp 
= "";
                        
for(int j = 1; j <= count; j++){
                                System.out.print(ss.getColumnName(j)
+"        ");
                                temp 
= temp + ss.getColumnName(j)+"              ";
                        }

                        col.add(temp);
                        System.out.println(
" ");
                        
                        
while(rs.next()){        
                                temp 
= "";
                                
for (int i = 1; i <= count;i++){
                                        System.out.print(rs.getString(i)
+" ");
                                        temp 
= temp + rs.getString(i)+"       ";
                                }

                                col.add(temp);
                                System.out.println(
" ");
                        }

                        
                        getResult(
1,col);
                        rs.close();
                        closeConnection();
                }
catch(Exception e){
                        e.printStackTrace();
                }

        }

        
        
public void UpdateDB(){
                
try{
                        getConnection();
                        String SQL 
= "update test set address = '上海'";
                        PreparedStatement pstmt  
= this.conn.prepareStatement(SQL);        
                        ResultSet rs 
= pstmt.executeQuery();
                        
this.conn.commit();
                        
                        SQL 
= "select id ,name ,age ,address  from test";
                        Statement stmt 
= this.conn.createStatement();
                        rs 
= stmt.executeQuery(SQL);
                        ResultSetMetaData ss 
= rs.getMetaData();        
                        
int count = ss.getColumnCount();
                        
                        Collection col 
= new ArrayList();
                        
                        String temp 
= "";
                        
                        
for(int j = 1; j <= count; j++){
                                System.out.print(ss.getColumnName(j)
+"        ");
                                temp 
= temp + ss.getColumnName(j)+"              ";
                        }

                        col.add(temp);
                        
                        System.out.println(
" ");
                        
                        
while(rs.next()){        
                                temp 
= "";
                                
for (int i = 1; i <= count;i++){
                                        System.out.print(rs.getString(i)
+" ");
                                        temp 
= temp + rs.getString(i)+"       ";
                                }

                                col.add(temp);
                                System.out.println(
" ");
                        }

                         
                        getResult(
2,col);
                        rs.close();
                        closeConnection();
                }
catch(Exception e){
                        e.printStackTrace();
                }

                
        }

        
        
public void DeleteDB(){
                
try{
                        getConnection();
                        String SQL 
= "delete from test where id = '0008'";
                        PreparedStatement pstmt  
= this.conn.prepareStatement(SQL);
                        ResultSet rs 
= pstmt.executeQuery();  
                        
this.conn.commit();
                        
                        SQL 
= "select id ,name ,age ,address  from test";
                        Statement stmt 
= this.conn.createStatement();
                        rs 
= stmt.executeQuery(SQL);
                        ResultSetMetaData ss 
= rs.getMetaData();        
                        
int count = ss.getColumnCount();
                        
                        Collection col 
= new ArrayList();
                        
                        String temp 
= "";
                        
                        
for(int j = 1; j <= count; j++){
                                System.out.print(ss.getColumnName(j)
+"        ");
                                temp 
= temp + ss.getColumnName(j)+"              ";
                        }

                        col.add(temp);
                        System.out.println(
" ");
                        
                        
while(rs.next()){        
                                temp 
= "";
                                
for (int i = 1; i <= count;i++){
                                        System.out.print(rs.getString(i)
+" ");
                                        temp 
= temp + rs.getString(i)+"       ";
                                }

                                col.add(temp);
                                System.out.println(
" ");
                        }

                        
                        getResult(
3,col);
                        rs.close();
                        closeConnection();
                }
catch(Exception e){
                        e.printStackTrace();
                }

                
        }

        
        
public void excute(int tag){
                
if(tag == 0){
                        System.out.println(
"进行查询操作");
                        SelectDB();
                }
else if(tag == 1){
                        System.out.println(
"进行添加操作");
                        InsertDB();
                }
else if(tag == 2){
                        System.out.println(
"进行修改操作");
                        UpdateDB();
                }
else if(tag == 3){
                        System.out.println(
"进行删除操作");
                        DeleteDB();
                }
else{
                        System.out.println(
"标志码输入错误");
                }

        }

        
        
public static void main(String[] args) 
        
{
                ContactTest  ct 
= new ContactTest ();
                ct.flag 
= 3;  //0-查询;1-添加;2-修改;3-删除
                ct.excute(ct.flag);
        }

        
}


------------------------------------------------------------ 3.将上例中的txt文档全部替换成csv文档(表格文档)
package ConnectionTest;

import java.io.BufferedWriter;
import java.io.File;
import java.io.FileOutputStream;
import java.io.FileWriter;
import java.io.IOException;
import java.io.OutputStreamWriter;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Iterator;

public class ContactTest {        
        
private Connection conn = null;
        
private int flag;
        
        
static final String LINE_SEPARATOR = System.getProperty("line.separator");
        
        
public void getConnection(){
                
try{
                        String JDBC_URL 
= "jdbc:pointbase:server://localhost:9092/test";
                        String JDBC_DRIVER
="com.pointbase.jdbc.jdbcUniversalDriver";                                        
                        String USER 
= "PBPUBLIC";
                        String PASSWORD 
= "PBPUBLIC";
                
                        Class.forName(JDBC_DRIVER).newInstance();
                        conn 
= DriverManager.getConnection(JDBC_URL,USER,PASSWORD);
                        System.out.println(
"connection success");
                }
catch(Exception e){
                        e.printStackTrace();
                }

        }

        
        
public void closeConnection() throws SQLException{
                
if(this.conn != null){
                        conn.close();
                }

        }

        
        
public void getResult(int flag,Collection col) throws IOException{
                String name 
= null;
                
if(flag == 0){
                        System.out.println(
"输出查询信息");
                        name 
= "select.csv";
                        WriterOut(name,col);
                }
else if(flag == 1){
                        System.out.println(
"输出插入信息");
                        name 
= "insert.csv";
                        WriterOut(name,col);
                }
else if(flag == 2){
                        System.out.println(
"输出修改信息");
                        name 
= "update.csv";
                        WriterOut(name,col);
                }
else if(flag == 3){
                        System.out.println(
"输出删除信息");
                        name 
= "delete.csv";
                        WriterOut(name,col);
                }
else{
                        System.out.println(
"标志码输入错误");
                }

        }

        
        
public void WriterOut(String name,Collection list) throws IOException{
                String path 
= "d:/"+name;
        
        BufferedWriter writer 
= new BufferedWriter(new OutputStreamWriter(new FileOutputStream(path)));
        
int count = list.size();
        String csvData[] 
= new String[count];
        
        Iterator it 
= list.iterator();
        
        
int i = 0;
        
while(it.hasNext()){
                String temp 
= (String)it.next();
                System.out.println(temp);
                csvData[i] 
= temp;
                i
++;
        }

        
        
for(int j = 0;j < csvData.length;j++)
                
{
                        writer.write(csvData[j] 
+ LINE_SEPARATOR);
                        
                }

        writer.close();
       
        }

        
        
public void SelectDB(){
                
try{
                        getConnection();
                        Statement stmt  
= this.conn.createStatement();
                        String SQL 
= "select id ,name ,age ,address  from test";
                        ResultSet rs 
= stmt.executeQuery(SQL);

                        Collection col 
= new ArrayList();
                        
                        ResultSetMetaData ss 
= rs.getMetaData();        
                        
int count = ss.getColumnCount();

                        String temp 
= "";
                        
for(int j = 1; j <= count; j++){
                                System.out.print(ss.getColumnName(j)
+"        ");
                                
if(j == count){
                                        temp 
= temp + ss.getColumnName(j);
                                }
else{
                                        temp 
= temp + ss.getColumnName(j)+",";
                                }

                        }

                        col.add(temp);
         
                        System.out.println(
" ");
                        
                        
while(rs.next()){        
                                temp 
= "";
                                
for (int i = 1; i <= count;i++){
                                        System.out.print(rs.getString(i)
+" ");
                                        
if(i == count){
                                                temp 
= temp + "\""+ rs.getString(i) + "\"";
                                        }
else{
                                                temp 
= temp + "\""+ rs.getString(i) + "\",";
                                        }
        
                                }

                                col.add(temp);   
//
                                System.out.println(" ");
                        }

                        getResult(
0,col);
                        closeConnection();
                }
catch(Exception e){
                        e.printStackTrace();
                }

        }

        
        
public void InsertDB(){
                
try{
                        getConnection();
                        String SQL 
= "insert into test values('0011','sandy','25','shanghai')";
                        PreparedStatement pstmt  
= this.conn.prepareStatement(SQL);
                        
                        ResultSet rs 
= pstmt.executeQuery();
                        conn.commit();
                        
                        SQL 
= "select id ,name ,age ,address  from test";
                        Statement stmt 
= this.conn.createStatement();
                        rs 
= stmt.executeQuery(SQL);
                        ResultSetMetaData ss 
= rs.getMetaData();        
                        
int count = ss.getColumnCount();

                        Collection col 
= new ArrayList();
                        
            String temp 
= "";
                        
for(int j = 1; j <= count; j++){
                                System.out.print(ss.getColumnName(j)
+"        ");
                                
if(j == count){
                                        temp 
= temp + ss.getColumnName(j);
                                }
else{
                                        temp 
= temp + ss.getColumnName(j)+",";
                                }

                        }

                        col.add(temp);
                        System.out.println(
" ");
            
                        
while(rs.next()){        
                                temp 
= "";
                                
for (int i = 1; i <= count;i++){
                                        System.out.print(rs.getString(i)
+" ");
                                        
if(i == count){
                                                temp 
= temp + "\""+ rs.getString(i) + "\"";
                                        }
else{
                                                temp 
= temp + "\""+ rs.getString(i) + "\",";
                                        }

                                }

                                col.add(temp);
                                System.out.println(
" ");
                        }

                        getResult(
1,col);
                        closeConnection();
                }
catch(Exception e){
                        e.printStackTrace();
                }

        }

        
        
public void UpdateDB(){
                
try{
                        getConnection();
                        String SQL 
= "update test set address = '上海'";
                        PreparedStatement pstmt  
= this.conn.prepareStatement(SQL);
                        
                        ResultSet rs 
= pstmt.executeQuery();
                        conn.commit();
                        
                        SQL 
= "select id ,name ,age ,address  from test";
                        Statement stmt 
= this.conn.createStatement();
                        rs 
= stmt.executeQuery(SQL);
                        ResultSetMetaData ss 
= rs.getMetaData();        
                        
int count = ss.getColumnCount();
                        
                        Collection col 
= new ArrayList();
                        
            String temp 
= "";
                        
                        
for(int j = 1; j <= count; j++){
                                System.out.print(ss.getColumnName(j)
+"        ");
                                
if(j == count){
                                        temp 
= temp + ss.getColumnName(j);
                                }
else{
                                        temp 
= temp + ss.getColumnName(j)+",";
                                }

                        }

                        col.add(temp);

                        System.out.println(
" ");
                        
                        
while(rs.next()){        
                                temp 
= "";
                                
for (int i = 1; i <= count;i++){
                                        System.out.print(rs.getString(i)
+" ");
                                        
if(i == count){
                                                temp 
= temp + "\""+ rs.getString(i) + "\"";
                                        }
else{
                                                temp 
= temp + "\""+ rs.getString(i) + "\",";
                                        }

                                }

                                col.add(temp);
                                System.out.println(
" ");
                        }

                        getResult(
2,col);
                        closeConnection();
                }
catch(Exception e){
                        e.printStackTrace();
                }

                
        }

        
        
public void DeleteDB(){
                
try{
                        getConnection();
                        String SQL 
= "delete from test where id = '0008'";
                        PreparedStatement pstmt  
= this.conn.prepareStatement(SQL);
                        
                        ResultSet rs 
= pstmt.executeQuery();        
                        conn.commit();
                        
                        SQL 
= "select id ,name ,age ,address  from test";
                        Statement stmt 
= this.conn.createStatement();
                        rs 
= stmt.executeQuery(SQL);
                        ResultSetMetaData ss 
= rs.getMetaData();        
                        
int count = ss.getColumnCount();
                        
                        Collection col 
= new ArrayList();
                        
            String temp 
= "";
                        
                        
for(int j = 1; j <= count; j++){
                                System.out.print(ss.getColumnName(j)
+"        ");
                                
if(j == count){
                                        temp 
= temp + ss.getColumnName(j);
                                }
else{
                                        temp 
= temp + ss.getColumnName(j)+",";
                                }

                        }

                        col.add(temp);
                        System.out.println(
" ");
                        
                        
while(rs.next()){        
                                temp 
= "";
                                
for (int i = 1; i <= count;i++){
                                        System.out.print(rs.getString(i)
+" ");
                                        
if(i == count){
                                                temp 
= temp + "\""+ rs.getString(i) + "\"";
                                        }
else{
                                                temp 
= temp + "\""+ rs.getString(i) + "\",";
                                        }

                                }

                                col.add(temp);
                                System.out.println(
" ");
                        }

                        getResult(
3,col);
                        closeConnection();
                }
catch(Exception e){
                        e.printStackTrace();
                }

                
        }

        
        
public void excute(int tag){
                
if(tag == 0){
                        System.out.println(
"进行查询操作");
                        SelectDB();
                }
else if(tag == 1){
                        System.out.println(
"进行添加操作");
                        InsertDB();
                }
else if(tag == 2){
                        System.out.println(
"进行修改操作");
                        UpdateDB();
                }
else if(tag == 3){
                        System.out.println(
"进行删除操作");
                        DeleteDB();
                }
else{
                        System.out.println(
"标志码输入错误");
                }

        }

        
        
public static void main(String[] args) 
        
{
                ContactTest  ct 
= new ContactTest ();
                ct.flag 
= 3;  //0-查询;1-添加;2-修改;3-删除
                ct.excute(ct.flag);
        }

        
}

----------------------------------------------------------------------------------------------------------- 4.在上例的基础上对程序进行了修改,通过从配置文件中读取数据库信息 在目录下增加config.properties文件,内容为: db_driver = com.pointbase.jdbc.jdbcUniversalDriver db_url = jdbc:pointbase:server://localhost:9092/test db_user = PBPUBLIC db_password = PBPUBLIC 格式一定要按照 key = value 的写法 ----------------------------------------------------------------------------------------------------------- 主程序:
package ConnectionTest;

import java.io.BufferedWriter;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStreamWriter;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Iterator;
import java.util.Properties;

public class ContactTest {        
        
private Connection conn = null;
        
private int flag;
        
        
static final String LINE_SEPARATOR = System.getProperty("line.separator");
        
        
public void getConnection(){
                
try{
                        
/*
                         * 修改了程序,通过从配置文件中取得数据库信息
                         
*/

                         File file 
= new File("./src/test/ConnectionTest/config.properties");  //确定你的目录路径
                 Properties props = new Properties();

                 props.load(
new FileInputStream(file));
                        
                        
                        String JDBC_URL 
= props.getProperty("db_url");
                        String JDBC_DRIVER
= props.getProperty("db_driver");;                                        
                        String USER 
= props.getProperty("db_user");;
                        String PASSWORD 
= props.getProperty("db_password");;
                
                        Class.forName(JDBC_DRIVER).newInstance();
                        conn 
= DriverManager.getConnection(JDBC_URL,USER,PASSWORD);
                        System.out.println(
"connection success");
                }
catch(Exception e){
                        e.printStackTrace();
                }

        }

        
        
public void closeConnection() throws SQLException{
                
if(this.conn != null){
                        conn.close();
                }

        }

        
        
public void getResult(int flag,Collection col) throws IOException{
                String name 
= null;
                
if(flag == 0){
                        System.out.println(
"输出查询信息");
                        name 
= "select.csv";
                        WriterOut(name,col);
                }
else if(flag == 1){
                        System.out.println(
"输出插入信息");
                        name 
= "insert.csv";
                        WriterOut(name,col);
                }
else if(flag == 2){
                        System.out.println(
"输出修改信息");
                        name 
= "update.csv";
                        WriterOut(name,col);
                }
else if(flag == 3){
                        System.out.println(
"输出删除信息");
                        name 
= "delete.csv";
                        WriterOut(name,col);
                }
else{
                        System.out.println(
"标志码输入错误");
                }

        }

        
        
public void WriterOut(String name,Collection list) throws IOException{
                String path 
= "d:/"+name;
        
        BufferedWriter writer 
= new BufferedWriter(new OutputStreamWriter(new FileOutputStream(path)));
        
int count = list.size();

        String csvData[] 
= new String[count];
        
        Iterator it 
= list.iterator();
        
        
int i = 0;
        
while(it.hasNext()){
                String temp 
= (String)it.next();
                System.out.println(temp);
                csvData[i] 
= temp;
                i
++;
        }

        
        
for(int j = 0;j < csvData.length;j++)
                
{
                        writer.write(csvData[j] 
+ LINE_SEPARATOR);
                        
                }

        writer.close();
       
        }

        
        
public void SelectDB(){
                
try{
                        getConnection();
                        Statement stmt  
= this.conn.createStatement();
                        String SQL 
= "select id ,name ,age ,address  from test";
                        ResultSet rs 
= stmt.executeQuery(SQL);

                        Collection col 
= new ArrayList();
                        
                        ResultSetMetaData ss 
= rs.getMetaData();        
                        
int count = ss.getColumnCount();

                        String temp 
= "";
                        
for(int j = 1; j <= count; j++){
                                System.out.print(ss.getColumnName(j)
+"        ");

                                
if(j == count){
                                        temp 
= temp + ss.getColumnName(j);
                                }
else{
                                        temp 
= temp + ss.getColumnName(j)+",";
                                }

                        }

                        col.add(temp);
         
                        System.out.println(
" ");
                        
                        
while(rs.next()){        
                                temp 
= "";
                                
for (int i = 1; i <= count;i++){
                                        System.out.print(rs.getString(i)
+" ");
                                        
if(i == count){
                                                temp 
= temp + "\""+ rs.getString(i) + "\"";
                                        }
else{
                                                temp 
= temp + "\""+ rs.getString(i) + "\",";
                                        }
        
                                }

                                col.add(temp);   
//
                                System.out.println(" ");
                        }

                        getResult(
0,col);
                        closeConnection();
                }
catch(Exception e){
                        e.printStackTrace();
                }

        }

        
        
public void InsertDB(){
                
try{
                        getConnection();
                        String SQL 
= "insert into test values('0011','sandy','25','shanghai')";
                        PreparedStatement pstmt  
= this.conn.prepareStatement(SQL);
                        
                        ResultSet rs 
= pstmt.executeQuery();
                        conn.commit();
                        
                        SQL 
= "select id ,name ,age ,address  from test";
                        Statement stmt 
= this.conn.createStatement();
                        rs 
= stmt.executeQuery(SQL);
                        ResultSetMetaData ss 
= rs.getMetaData();        
                        
int count = ss.getColumnCount();

                        Collection col 
= new ArrayList();
                        
            String temp 
= "";
                        
for(int j = 1; j <= count; j++){
                                System.out.print(ss.getColumnName(j)
+"        ");
                                
if(j == count){
                                        temp 
= temp + ss.getColumnName(j);
                                }
else{
                                        temp 
= temp + ss.getColumnName(j)+",";
                                }

                        }

                        col.add(temp);
                        System.out.println(
" ");
            
                        
while(rs.next()){        
                                temp 
= "";
                                
for (int i = 1; i <= count;i++){
                                        System.out.print(rs.getString(i)
+" ");
                                        
if(i == count){
                                                temp 
= temp + "\""+ rs.getString(i) + "\"";
                                        }
else{
                                                temp 
= temp + "\""+ rs.getString(i) + "\",";
                                        }

                                }

                                col.add(temp);
                                System.out.println(
" ");
                        }

                        getResult(
1,col);
                        closeConnection();
                }
catch(Exception e){
                        e.printStackTrace();
                }

        }

        
        
public void UpdateDB(){
                
try{
                        getConnection();
                        String SQL 
= "update test set address = '上海'";
                        PreparedStatement pstmt  
= this.conn.prepareStatement(SQL);
                        
                        ResultSet rs 
= pstmt.executeQuery();
                        conn.commit();
                        
                        SQL 
= "select id ,name ,age ,address  from test";
                        Statement stmt 
= this.conn.createStatement();
                        rs 
= stmt.executeQuery(SQL);
                        ResultSetMetaData ss 
= rs.getMetaData();        
                        
int count = ss.getColumnCount();
                        
                        Collection col 
= new ArrayList();
                        
            String temp 
= "";
                        
                        
for(int j = 1; j <= count; j++){
                                System.out.print(ss.getColumnName(j)
+"        ");
                                
if(j == count){
                                        temp 
= temp + ss.getColumnName(j);
                                }
else{
                                        temp 
= temp + ss.getColumnName(j)+",";
                                }

                        }

                        col.add(temp);

                        System.out.println(
" ");
                        
                        
while(rs.next()){        
                                temp 
= "";
                                
for (int i = 1; i <= count;i++){
                                        System.out.print(rs.getString(i)
+" ");
                                        
if(i == count){
                                                temp 
= temp + "\""+ rs.getString(i) + "\"";
                                        }
else{
                                                temp 
= temp + "\""+ rs.getString(i) + "\",";
                                        }

                                }

                                col.add(temp);
                                System.out.println(
" ");
                        }

                        getResult(
2,col);
                        closeConnection();
                }
catch(Exception e){
                        e.printStackTrace();
                }

                
        }

        
        
public void DeleteDB(){
                
try{
                        getConnection();
                        String SQL 
= "delete from test where id = '0008'";
                        PreparedStatement pstmt  
= this.conn.prepareStatement(SQL);
                        
                        ResultSet rs 
= pstmt.executeQuery();        
                        conn.commit();
                        
                        SQL 
= "select id ,name ,age ,address  from test";
                        Statement stmt 
= this.conn.createStatement();
                        rs 
= stmt.executeQuery(SQL);
                        ResultSetMetaData ss 
= rs.getMetaData();        
                        
int count = ss.getColumnCount();
                        
                        Collection col 
= new ArrayList();
                        
            String temp 
= "";
                        
                        
for(int j = 1; j <= count; j++){
                                System.out.print(ss.getColumnName(j)
+"        ");
                                
if(j == count){
                                        temp 
= temp + ss.getColumnName(j);
                                }
else{
                                        temp 
= temp + ss.getColumnName(j)+",";
                                }

                        }

                        col.add(temp);
                        System.out.println(
" ");
                        
                        
while(rs.next()){        
                                temp 
= "";
                                
for (int i = 1; i <= count;i++){
                                        System.out.print(rs.getString(i)
+" ");
                                        
if(i == count){
                                                temp 
= temp + "\""+ rs.getString(i) + "\"";
                                        }
else{
                                                temp 
= temp + "\""+ rs.getString(i) + "\",";
                                        }

                                }

                                col.add(temp);
                                System.out.println(
" ");
                        }

                        getResult(
3,col);
                        closeConnection();
                }
catch(Exception e){
                        e.printStackTrace();
                }

                
        }

        
        
public void excute(int tag){
                
if(tag == 0){
                        System.out.println(
"进行查询操作");
                        SelectDB();
                }
else if(tag == 1){
                        System.out.println(
"进行添加操作");
                        InsertDB();
                }
else if(tag == 2){
                        System.out.println(
"进行修改操作");
                        UpdateDB();
                }
else if(tag == 3){
                        System.out.println(
"进行删除操作");
                        DeleteDB();
                }
else{
                        System.out.println(
"标志码输入错误");
                }

        }

        
        
public static void main(String[] args) 
        
{
                ContactTest  ct 
= new ContactTest ();
                ct.flag 
= 0;  //0-查询;1-添加;2-修改;3-删除
                ct.excute(ct.flag);
        }

        
}

----------------------------------------------------------------------------------------------------------- 5.在上例的基础上修改程序,通过xml配置文件得到数据库信息 更新程序: ----------------------------------------------------------------------------------------------------------- 当前目录下新建config.xml文件: 文件内容: <Config> <DBConfig> <driver>com.pointbase.jdbc.jdbcUniversalDriver</driver> //driver信息 <url>jdbc:pointbase:server://localhost:9092/test</url> //url信息 <user>PBPUBLIC</user> //数据库user <password>PBPUBLIC</password> //数据库password </DBConfig> <DBOperation> <Select> <SQL>select id ,name ,age ,address from test</SQL> //sql语句,用来查询 <Text>select.csv</Text> //查询结果的输出文件名 </Select> <Insert> <SQL>insert into test values('0011','sandy','25','shanghai')</SQL> <Text>insert.csv</Text> </Insert> <Update> <SQL>update test set address = '上海'</SQL> <Text>update.csv</Text> </Update> <Delete> <SQL>delete from test where id = '0008'</SQL> <Text>delete.csv</Text> </Delete> </DBOperation> </Config> -------------------------------------------------------------------------------------------------------- 新建一个.java文件,专门用来解析xml,这里我用的是开源的工具jdom,现在比较流行 新建文件:XmlParse.java 在同一个package内 -------------------------------------------------------------------------------------------------------- package ConnectionTest; import java.io.IOException; import java.util.HashMap; import org.jdom.Document; import org.jdom.Element; import org.jdom.JDOMException; import org.jdom.input.SAXBuilder; public class XmlParse { private HashMap configTable= new HashMap(); public HashMap parseXML() throws JDOMException, IOException{ SAXBuilder builder = new SAXBuilder(); Document readDoc = builder.build("src.test/ConnectionTest/config.xml"); Element config = readDoc.getRootElement(); System.out.println(config.getName()); Element e = config.getChild("DBConfig"); HashMap dbConfig = new HashMap(); configTable.put("dbconfig_driver",e.getChildText("driver")); configTable.put("dbconfig_url",e.getChildText("driver")); configTable.put("dbconfig_user",e.getChildText("user")); configTable.put("dbconfig_password",e.getChildText("password")); HashMap dbOper = new HashMap(); e = config.getChild("DBOperation"); Element c = e.getChild("Select"); configTable.put("dboperation_selectSQL",c.getChildText("SQL")); configTable.put("dboperation_selectText",c.getChildText("Text")); c = e.getChild("Insert"); configTable.put("dboperation_insertSQL",c.getChildText("SQL")); configTable.put("dboperation_insertText",c.getChildText("Text")); c = e.getChild("Update"); configTable.put("dboperation_updateSQL",c.getChildText("SQL")); configTable.put("dboperation_updateText",c.getChildText("Text")); c = e.getChild("Delete"); configTable.put("dboperation_deleteSQL",c.getChildText("SQL")); configTable.put("dboperation_deleteText",c.getChildText("Text")); return configTable; } } -------------------------------------------------------------------------------------------------------- 最后是主程序修改: -------------------------------------------------------------------------------------------------------- package ConnectionTest; import java.io.BufferedWriter; //import java.io.File; //import java.io.FileInputStream; import java.io.FileOutputStream; import java.io.IOException; import java.io.OutputStreamWriter; import java.sql.Connection; import java.sql.DriverManager; import java.sql.PreparedStatement; import java.sql.ResultSet; import java.sql.ResultSetMetaData; import java.sql.SQLException; import java.sql.Statement; import java.util.ArrayList; import java.util.Collection; import java.util.HashMap; import java.util.Iterator; import org.jdom.JDOMException; public class ContactTest { private Connection conn = null; private int flag; private HashMap config = new HashMap(); //存放从config.xml中得到的配置信息 static final String LINE_SEPARATOR = System.getProperty("line.separator"); /* * 增加了构造器,得到解析后的xml的配置信息列表 */ public ContactTest() throws JDOMException, IOException{ XmlParse xml = new XmlParse(); config = xml.parseXML(); } public void getConnection(){ try{ /* * 修改了程序,通过从配置文件中取得数据库信息 */ /* File file = new File("./src/test/ConnectionTest/config.properties"); //确定你的目录路径 Properties props = new Properties(); props.load(new FileInputStream(file)); String JDBC_URL = props.getProperty("db_url"); String JDBC_DRIVER= props.getProperty("db_driver"); String USER = props.getProperty("db_user"); String PASSWORD = props.getProperty("db_password"); */ String JDBC_URL = (String)config.get("dbconfig_url"); String JDBC_DRIVER= (String)config.get("dbconfig_driver"); String USER = (String)config.get("dbconfig_user"); String PASSWORD = (String)config.get("dbconfig_password"); Class.forName(JDBC_DRIVER).newInstance(); conn = DriverManager.getConnection(JDBC_URL,USER,PASSWORD); System.out.println("connection success-------------"); }catch(Exception e){ e.printStackTrace(); } } public void closeConnection() throws SQLException{ if(this.conn != null){ conn.close(); } } public void getResult(int flag,Collection col) throws IOException{ String name = null; if(flag == 0){ System.out.println("输出查询信息"); name = (String)config.get("dboperation_selectText"); //从配置中得到文件名,不再是固定文件名了 WriterOut(name,col); }else if(flag == 1){ System.out.println("输出插入信息"); name = (String)config.get("dboperation_insertText");; WriterOut(name,col); }else if(flag == 2){ System.out.println("输出修改信息"); name = (String)config.get("dboperation_updateText");; WriterOut(name,col); }else if(flag == 3){ System.out.println("输出删除信息"); name = (String)config.get("dboperation_deleteText");; WriterOut(name,col); }else{ System.out.println("标志码输入错误"); } } public void WriterOut(String name,Collection list) throws IOException{ String path = "d:/"+name; BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(new FileOutputStream(path))); int count = list.size(); String csvData[] = new String[count]; Iterator it = list.iterator(); int i = 0; while(it.hasNext()){ String temp = (String)it.next(); System.out.println(temp); csvData[i] = temp; i++; } for(int j = 0;j < csvData.length;j++) { writer.write(csvData[j] + LINE_SEPARATOR); } writer.close(); } public void SelectDB(){ try{ getConnection(); Statement stmt = this.conn.createStatement(); String SQL = (String)config.get("dboperation_selectSQL"); ResultSet rs = stmt.executeQuery(SQL); Collection col = new ArrayList(); //集合,用来存放数据库信息 ResultSetMetaData ss = rs.getMetaData(); int count = ss.getColumnCount(); String temp = ""; for(int j = 1; j <= count; j++){ System.out.print(ss.getColumnName(j)+" "); if(j == count){ temp = temp + ss.getColumnName(j); }else{ temp = temp + ss.getColumnName(j)+","; } } col.add(temp); System.out.println(" "); while(rs.next()){ temp = ""; for (int i = 1; i <= count;i++){ System.out.print(rs.getString(i)+" "); if(i == count){ temp = temp + "\""+ rs.getString(i) + "\""; }else{ temp = temp + "\""+ rs.getString(i) + "\","; } } col.add(temp); // System.out.println(" "); } getResult(0,col); closeConnection(); }catch(Exception e){ e.printStackTrace(); } } public void InsertDB(){ try{ getConnection(); String SQL = (String)config.get("dboperation_insertSQL"); PreparedStatement pstmt = this.conn.prepareStatement(SQL); ResultSet rs = pstmt.executeQuery(); conn.commit(); SQL = (String)config.get("dboperation_selectSQL");; Statement stmt = this.conn.createStatement(); rs = stmt.executeQuery(SQL); ResultSetMetaData ss = rs.getMetaData(); int count = ss.getColumnCount(); Collection col = new ArrayList(); String temp = ""; for(int j = 1; j <= count; j++){ System.out.print(ss.getColumnName(j)+" "); if(j == count){ temp = temp + ss.getColumnName(j); }else{ temp = temp + ss.getColumnName(j)+","; } } col.add(temp); System.out.println(" "); while(rs.next()){ temp = ""; for (int i = 1; i <= count;i++){ System.out.print(rs.getString(i)+" "); if(i == count){ temp = temp + "\""+ rs.getString(i) + "\""; }else{ temp = temp + "\""+ rs.getString(i) + "\","; } } col.add(temp); System.out.println(" "); } getResult(1,col); closeConnection(); }catch(Exception e){ e.printStackTrace(); } } public void UpdateDB(){ try{ getConnection(); String SQL = (String)config.get("dboperation_updateSQL"); PreparedStatement pstmt = this.conn.prepareStatement(SQL); ResultSet rs = pstmt.executeQuery(); conn.commit(); SQL = (String)config.get("dboperation_selectSQL"); Statement stmt = this.conn.createStatement(); rs = stmt.executeQuery(SQL); ResultSetMetaData ss = rs.getMetaData(); int count = ss.getColumnCount(); Collection col = new ArrayList(); String temp = ""; for(int j = 1; j <= count; j++){ System.out.print(ss.getColumnName(j)+" "); if(j == count){ temp = temp + ss.getColumnName(j); }else{ temp = temp + ss.getColumnName(j)+","; } } col.add(temp); System.out.println(" "); while(rs.next()){ temp = ""; for (int i = 1; i <= count;i++){ System.out.print(rs.getString(i)+" "); if(i == count){ temp = temp + "\""+ rs.getString(i) + "\""; }else{ temp = temp + "\""+ rs.getString(i) + "\","; } } col.add(temp); System.out.println(" "); } getResult(2,col); closeConnection(); }catch(Exception e){ e.printStackTrace(); } } public void DeleteDB(){ try{ getConnection(); String SQL = (String)config.get("dboperation_deleteSQL"); PreparedStatement pstmt = this.conn.prepareStatement(SQL); ResultSet rs = pstmt.executeQuery(); conn.commit(); SQL = (String)config.get("dboperation_selectSQL"); Statement stmt = this.conn.createStatement(); rs = stmt.executeQuery(SQL); ResultSetMetaData ss = rs.getMetaData(); int count = ss.getColumnCount(); Collection col = new ArrayList(); String temp = ""; for(int j = 1; j <= count; j++){ System.out.print(ss.getColumnName(j)+" "); if(j == count){ temp = temp + ss.getColumnName(j); }else{ temp = temp + ss.getColumnName(j)+","; } } col.add(temp); System.out.println(" "); while(rs.next()){ temp = ""; for (int i = 1; i <= count;i++){ System.out.print(rs.getString(i)+" "); if(i == count){ temp = temp + "\""+ rs.getString(i) + "\""; }else{ temp = temp + "\""+ rs.getString(i) + "\","; } } col.add(temp); System.out.println(" "); } getResult(3,col); closeConnection(); }catch(Exception e){ e.printStackTrace(); } } public void excute(int tag){ if(tag == 0){ System.out.println("进行查询操作"); SelectDB(); }else if(tag == 1){ System.out.println("进行添加操作"); InsertDB(); }else if(tag == 2){ System.out.println("进行修改操作"); UpdateDB(); }else if(tag == 3){ System.out.println("进行删除操作"); DeleteDB(); }else{ System.out.println("标志码输入错误"); } } public static void main(String[] args) throws JDOMException, IOException { ContactTest ct = new ContactTest (); ct.flag = 0; //0-查询;1-添加;2-修改;3-删除 ct.excute(ct.flag); } } 为了便于你更好理解这些程序,我增加了注释,建议使用editplus来看,这样比较好区分注释 config.xml: ---------------------------------------------------------------------------------------------------------- <!----------首先是根节点<config>---------> <Config> <!----------然后是子节点<DBConfig>,用来存放数据库的配置信息---------> <DBConfig> <!-------在该节点下的第一个配置参数<dirver>:数据库驱动,<driver></driver>是标签,当中就是你的配置信息-------> <driver>com.pointbase.jdbc.jdbcUniversalDriver</driver> <!-------在该节点下的第二个配置参数<url>:数据库url地址---------> <url>jdbc:pointbase:server://localhost:9092/test</url> <!-------在该节点下的第三个配置参数<user>:数据库用户名---------> <user>PBPUBLIC</user> <!-------在该节点下的第四个配置参数<password>:数据库密码---------> <password>PBPUBLIC</password> </DBConfig> <!----------然后是子节点<DBOperation>,用来存放对数据库的操作信息,这个和<DBConfig>是同一个级别的---------> <DBOperation> <!-------在该节点下的第一个子节点<select>:对数据库进行select操作---------> <Select> <!-------在该子节点下有两个具体的配置参数---------> <!-------配置参数<SQL>,对数据库进行select的操作的查询语句,就是将在程序中的查询语句在这里定义了------> <SQL>select id ,name ,age ,address from test</SQL> <!--配置参数<Text>,根据你的业务需求需要在不同的数据库操作后输出不同的文件信息,这里存放输出的文件名--> <Text>select.csv</Text> </Select> <!-------在该节点下的第二个子节点<insert>:对数据库进行insert操作---------> <Insert> <SQL>insert into test values('0011','sandy','25','shanghai')</SQL> <Text>insert.csv</Text> </Insert> <!-------在该节点下的第三个子节点<update>:对数据库进行update操作---------> <Update> <SQL>update test set address = '上海'</SQL> <Text>update.csv</Text> </Update> <!-------在该节点下的第四个子节点<delete>:对数据库进行delete操作---------> <Delete> <SQL>delete from test where id = '0008'</SQL> <Text>delete.csv</Text> </Delete> </DBOperation> </Config> XmlParse.java 增加注释: ----------------------------------------------------------------------------------------------------------- package ConnectionTest; import java.io.IOException; import java.util.HashMap; import org.jdom.Document; import org.jdom.Element; import org.jdom.JDOMException; import org.jdom.input.SAXBuilder; /* * 对xml进行解析,从xml中拿到所有的配置信息,放在集合中,采用HashMap集合方式 * HashMap是采用key = value的方式存放的,所以可以通过对应的key值得到相应的配置信息 * 这个和xml的标签和标签内容是一一对应的,例如<user>public</user>是标签,那么在 * HashMap中这配置信息的就可以存放为,key = "user",value = "public"来存放 * 具体的参照API文档 */ public class XmlParse { private HashMap configTable= new HashMap(); //生成一个HashMap,用来存放所有的配置信息 /* * 方法parseXML,具体执行解析xml文件 * 返回一个HashMap,就是将解析完成的含有配置信息的HashMap返回 */ public HashMap parseXML() throws JDOMException, IOException{ //固定格式,先生成解析器,再建立Document SAXBuilder builder = new SAXBuilder(); //将你要解析的xml文件导入,注意文件的路径,总是以工程文件的根目录为起点的 Document readDoc = builder.build("src.test/ConnectionTest/config.xml"); //Element为xml中元素节点,这里通过getRootElement()方法得到根节点 Element config = readDoc.getRootElement(); //通过根节点得到一个名字为"DBConfig"的子节点 Element e = config.getChild("DBConfig"); //在这个子节点下有四个具体的配置信息,我们通过e.getChildText()这个 //方法得到里面的具体的配置信息,就是<></>标签中间的部分,"driver"就是 //标签的名字 //再通过HashMap的put(key,value)的方法将这些信息保存到HashMap中 configTable.put("dbconfig_driver",e.getChildText("driver")); configTable.put("dbconfig_url",e.getChildText("url")); configTable.put("dbconfig_user",e.getChildText("user")); configTable.put("dbconfig_password",e.getChildText("password")); //再次通过根节点得到一个名字为"DBOperation"的子节点 e = config.getChild("DBOperation"); //找到该子节点下的一个名字为"Select"的子节点 Element c = e.getChild("Select"); //同样进行读取节点信息和HashMap的保存操作 configTable.put("dboperation_selectSQL",c.getChildText("SQL")); configTable.put("dboperation_selectText",c.getChildText("Text")); //以下同上 c = e.getChild("Insert"); configTable.put("dboperation_insertSQL",c.getChildText("SQL")); configTable.put("dboperation_insertText",c.getChildText("Text")); c = e.getChild("Update"); configTable.put("dboperation_updateSQL",c.getChildText("SQL")); configTable.put("dboperation_updateText",c.getChildText("Text")); c = e.getChild("Delete"); configTable.put("dboperation_deleteSQL",c.getChildText("SQL")); configTable.put("dboperation_deleteText",c.getChildText("Text")); //最后将解析完成,保存后的HashMap返回 return configTable; } } ContactTest.java 增加注释: -------------------------------------------------------------------------------------------------------- package ConnectionTest; import java.io.BufferedWriter; import java.io.FileOutputStream; import java.io.IOException; import java.io.OutputStreamWriter; import java.sql.Connection; import java.sql.DriverManager; import java.sql.PreparedStatement; import java.sql.ResultSet; import java.sql.ResultSetMetaData; import java.sql.SQLException; import java.sql.Statement; import java.util.ArrayList; import java.util.Collection; import java.util.HashMap; import java.util.Iterator; import org.jdom.JDOMException; public class ContactTest { private Connection conn = null; //数据库连接connection private int flag; //标志位,判断数据库操作 private HashMap config = new HashMap(); //存放从config.xml中得到的配置信息 //常量,分行标志符,从系统中获得的 static final String LINE_SEPARATOR = System.getProperty("line.separator"); /* * 增加了构造器,得到解析后的xml的配置信息列表 */ public ContactTest() throws JDOMException, IOException{ XmlParse xml = new XmlParse(); //声明一个对象,解析xml配置文件 config = xml.parseXML(); //调用解析方法,将返回的HashMap结果放入config中 } /* * 数据库连接操作 */ public void getConnection(){ try{ /* * 修改了程序,通过从配置文件中取得数据库信息 * 这里是从hashmap中拿到配置信息get("dbconfig_url")这个方法 * 是从hashmap中拿出key值为dbconfig_url的value的值,因为放入 * hashmap中的key,value类型都是object的,所以拿出来的时候要转换 * 格式成String */ String JDBC_URL = (String)config.get("dbconfig_url"); String JDBC_DRIVER= (String)config.get("dbconfig_driver"); String USER = (String)config.get("dbconfig_user"); String PASSWORD = (String)config.get("dbconfig_password"); Class.forName(JDBC_DRIVER).newInstance(); conn = DriverManager.getConnection(JDBC_URL,USER,PASSWORD); System.out.println("connection success-------------"); }catch(Exception e){ e.printStackTrace(); } } public void closeConnection() throws SQLException{ if(this.conn != null){ conn.close(); } } public void getResult(int flag,Collection col) throws IOException{ String name = null; if(flag == 0){ System.out.println("输出查询信息"); //这里要定义输出文件的文件名字,我们现在也是从hashmap中拿到文件名的值 //就是你在config.xml中看到的<text></text>标签中的文件名 name = (String)config.get("dboperation_selectText"); WriterOut(name,col); }else if(flag == 1){ System.out.println("输出插入信息"); name = (String)config.get("dboperation_insertText");; WriterOut(name,col); }else if(flag == 2){ System.out.println("输出修改信息"); name = (String)config.get("dboperation_updateText");; WriterOut(name,col); }else if(flag == 3){ System.out.println("输出删除信息"); name = (String)config.get("dboperation_deleteText");; WriterOut(name,col); }else{ System.out.println("标志码输入错误"); } } /* * 对查询的内容进行输出,并且控制输出格式 */ public void WriterOut(String name,Collection list) throws IOException{ String path = "d:/"+name; //输出路径 //这里定义了一个IO输出的包装器 BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(new FileOutputStream(path))); int count = list.size(); //计算总共要输出几行 /* * 修改程序,改变输出格式 */ String csvData[] = new String[count]; //这个你要求的csv文件的数据输出的数组 Iterator it = list.iterator(); //定义一个迭代器,用来遍历集合 int i = 0; //开始遍历集合,不断的从集合中取出纪录,直到遍历结束 while(it.hasNext()){ String temp = (String)it.next(); System.out.println(temp); csvData[i] = temp; //将取出的纪录放入数组中 i++; } //将数组中的纪录通过IO包装器放到文件中 for(int j = 0;j < csvData.length;j++) { //需要在输出文件是修改文件格式,达到csv的文本要求 writer.write(csvData[j] + LINE_SEPARATOR); } writer.close(); } public void SelectDB(){ try{ getConnection(); Statement stmt = this.conn.createStatement(); //这里的SQL语句也放到xml文件中去配置了 String SQL = (String)config.get("dboperation_selectSQL"); ResultSet rs = stmt.executeQuery(SQL); Collection col = new ArrayList(); //集合,用来存放数据库信息 ResultSetMetaData ss = rs.getMetaData(); int count = ss.getColumnCount(); /* * 这里加了些字段信息得内容,这里没有对字段的长度进行判断,所有在输出格式时会有偏差 */ String temp = ""; for(int j = 1; j <= count; j++){ System.out.print(ss.getColumnName(j)+" "); /* * 新增加的语句,为了达到csv文件的输出的格式 */ if(j == count){ temp = temp + ss.getColumnName(j); }else{ temp = temp + ss.getColumnName(j)+","; } } col.add(temp); //放入集合中,将一行的内容放到集合中去 System.out.println(" "); while(rs.next()){ temp = ""; for (int i = 1; i <= count;i++){ System.out.print(rs.getString(i)+" "); /* * 新增加的语句,为了达到csv文件的输出的格式 */ if(i == count){ temp = temp + "\""+ rs.getString(i) + "\""; }else{ temp = temp + "\""+ rs.getString(i) + "\","; } } col.add(temp); //放入集合中,将整合后的一行的内容放到集合中去 System.out.println(" "); } getResult(0,col); closeConnection(); }catch(Exception e){ e.printStackTrace(); } } public void InsertDB(){ try{ getConnection(); String SQL = (String)config.get("dboperation_insertSQL"); PreparedStatement pstmt = this.conn.prepareStatement(SQL); ResultSet rs = pstmt.executeQuery(); conn.commit(); SQL = (String)config.get("dboperation_selectSQL");; Statement stmt = this.conn.createStatement(); rs = stmt.executeQuery(SQL); ResultSetMetaData ss = rs.getMetaData(); int count = ss.getColumnCount(); Collection col = new ArrayList(); String temp = ""; for(int j = 1; j <= count; j++){ System.out.print(ss.getColumnName(j)+" "); if(j == count){ temp = temp + ss.getColumnName(j); }else{ temp = temp + ss.getColumnName(j)+","; } } col.add(temp); System.out.println(" "); while(rs.next()){ temp = ""; for (int i = 1; i <= count;i++){ System.out.print(rs.getString(i)+" "); if(i == count){ temp = temp + "\""+ rs.getString(i) + "\""; }else{ temp = temp + "\""+ rs.getString(i) + "\","; } } col.add(temp); System.out.println(" "); } getResult(1,col); closeConnection(); }catch(Exception e){ e.printStackTrace(); } } public void UpdateDB(){ try{ getConnection(); String SQL = (String)config.get("dboperation_updateSQL"); PreparedStatement pstmt = this.conn.prepareStatement(SQL); ResultSet rs = pstmt.executeQuery(); conn.commit(); SQL = (String)config.get("dboperation_selectSQL"); Statement stmt = this.conn.createStatement(); rs = stmt.executeQuery(SQL); ResultSetMetaData ss = rs.getMetaData(); int count = ss.getColumnCount(); Collection col = new ArrayList(); String temp = ""; for(int j = 1; j <= count; j++){ System.out.print(ss.getColumnName(j)+" "); if(j == count){ temp = temp + ss.getColumnName(j); }else{ temp = temp + ss.getColumnName(j)+","; } } col.add(temp); System.out.println(" "); while(rs.next()){ temp = ""; for (int i = 1; i <= count;i++){ System.out.print(rs.getString(i)+" "); if(i == count){ temp = temp + "\""+ rs.getString(i) + "\""; }else{ temp = temp + "\""+ rs.getString(i) + "\","; } } col.add(temp); System.out.println(" "); } getResult(2,col); closeConnection(); }catch(Exception e){ e.printStackTrace(); } } public void DeleteDB(){ try{ getConnection(); String SQL = (String)config.get("dboperation_deleteSQL"); PreparedStatement pstmt = this.conn.prepareStatement(SQL); ResultSet rs = pstmt.executeQuery(); conn.commit(); SQL = (String)config.get("dboperation_selectSQL"); Statement stmt = this.conn.createStatement(); rs = stmt.executeQuery(SQL); ResultSetMetaData ss = rs.getMetaData(); int count = ss.getColumnCount(); Collection col = new ArrayList(); String temp = ""; for(int j = 1; j <= count; j++){ System.out.print(ss.getColumnName(j)+" "); if(j == count){ temp = temp + ss.getColumnName(j); }else{ temp = temp + ss.getColumnName(j)+","; } } col.add(temp); System.out.println(" "); while(rs.next()){ temp = ""; for (int i = 1; i <= count;i++){ System.out.print(rs.getString(i)+" "); if(i == count){ temp = temp + "\""+ rs.getString(i) + "\""; }else{ temp = temp + "\""+ rs.getString(i) + "\","; } } col.add(temp); System.out.println(" "); } getResult(3,col); closeConnection(); }catch(Exception e){ e.printStackTrace(); } } public void excute(int tag){ if(tag == 0){ System.out.println("进行查询操作"); SelectDB(); }else if(tag == 1){ System.out.println("进行添加操作"); InsertDB(); }else if(tag == 2){ System.out.println("进行修改操作"); UpdateDB(); }else if(tag == 3){ System.out.println("进行删除操作"); DeleteDB(); }else{ System.out.println("标志码输入错误"); } } public static void main(String[] args) throws JDOMException, IOException { ContactTest ct = new ContactTest (); ct.flag = 0; //0-查询;1-添加;2-修改;3-删除 ct.excute(ct.flag); } } ------------------------------------------------------------------------------------------------ 6.java中所有的数据结构都是对象,通过运算符new为他们分配内存堆,这句话怎么理解? 应该说你这句话不太对,java中的一些基本数据类型,如int ,double ,long,boolean等这些基本类型不是对象,所以严格的来说java不是都是对象的,除了这些个之外其他的都是对象了。 java中要产生对象要具有生命力就要做两件事情,一是声明,这个就好像告诉别人你要生孩子了。二就是要具体分配一个空间给这个对象,让这个对象可以有自己的生命力,这个就是new,而空间就是指的内存空间,java中任何可以操作的对象都是需要得到自己的内存空间才能被使用的 ------------------------------------------------------------------------------------------------ 7.关于Iterator it = list.iterator(); 迭代器是通常是和集合一起用的,是一种java的模式,俗称迭代子,用来遍历整个集合,从集合中取数据 举例: package Iterator; import java.util.ArrayList; import java.util.Collection; import java.util.Iterator; public class IteratorTest { public static void main(String[] args){ Collection list = new ArrayList(); //定义一个ArrayList数组集合 list.add("3"); //向这个集合中放入数据 list.add("2"); list.add("1"); list.add("4"); list.add("5"); list.add("6"); Iterator it = list.iterator(); // 第一步 while(it.hasNext()){ //第二步 String temp = (String)it.next(); //取出元素 System.out.println(temp); } } } -------------------------------------------------------------------------------------------------- 8.找出在某一个文件夹下的某一类文件 package File; import java.io.File; import java.io.FilenameFilter; public class FileDemo { public static void main(String[] args){ -->首先声明一个File对象,指明你的文件目录路径,这里是我计算机中的东西,记住一定要是路径 File dir = new File("E:\\JAVA程序\\JAVA code\\copyfile\\core java"); -->Filter是你自己写的一个实现FilenameFilter接口的类,这个接口用用来过滤文件的名字,传入的参数是要过滤的关键字 Filter filter=new Filter("java"); -->这里将通过Filter过滤得到的文件列表放到一个数组中去 String fileList[] = dir.list(filter); System.out.println("找到文件数:"+fileList.length); -->下面就是通过遍历这个数组,从数组中取到文件名 for(int I = 0 ; I < fileList.length; I++){ -->因为在下面要对文件进行判断,所以这里要加上路径和文件名,否则下面的判断会因为找不到文件而判断错误 File tmpFile = new File("E:\\JAVA程序\\JAVA code\\copyfile\\core java\\"+fileList[I]); -->判断找到的这些文件是目录呢还是文件 if(tmpFile.isFile()){ System.out.println("文件:"+tmpFile); }else{ System.out.println("目录:"+tmpFile); } } } } -->实现过滤器接口的类,这个类主要作用是找出所有文件夹下的以extension结尾的文件 class Filter implements FilenameFilter{ String extension; Filter(String extension) { this.extension=extension; } public boolean accept(File directory,String filename){ -->这里的filename.endsWith("."+extension);方法就是找以.extension结尾的文件 return filename.endsWith("."+extension); } } 我所修改的程序简单的讲就是,查找所有在E:\\JAVA程序\\JAVA code\\copyfile\\core java这个目录下的以.java结尾的文件 ----------------------------------------------------------------------------------------------------------------- 9.关于接口的一些问题 Collection months=new ArrayList(); (这个ArrayList和Collection 我都不太明白) -------------------------------------------------------------------------------------------------------- Collection是集合的一个接口,ArrayList是集合的一种,这里ArrayList实现Collection这个接口,声明一个接口的对象需要new一个实现他的类。 Object s[]=months.toArray();  (这个地方也不明白) -------------------------------------------------------------------------------------------------------- Object是java中所有类的父类,months是前面生成的集合对象,是一个ArrayList的对象,这个对象有一个方法是toArray(),能够把这个集合中的转换成一个Object类型的对象数组 System.out.println(s[i].toString());(s[i].toString() 打印这个为什么就是数组里面的内容) --------------------------------------------------------------------------------------------------------- System.out.println()打印出来的是字符串,()内放的应该是String类型的值,这里用了 s[i].toString()这个语句,意思就是把数组中的一个对象转换成String类型然后输出 List months=new ArrayList();(这个地方List要换成ArrayLis才不报错 我也不知道为什么 我想只要上面那个明白了 下面这个也应该就明白了吧) ---------------------------------------------------------------------------------------------------------- 这里和Collection是相同的,List是一个集合的接口,ArrayList()是实现这个接口的类,同样也是生成一个接口对象需要new一个实现他的类 ========================================================================================================== 还有很多的问题没有列举出来,大家可以看看《查询的问题对各位大侠绝对是容易的,拜托了》这个帖子
posted on 2006-03-24 02:39 konhon 优华 阅读(643) 评论(0)  编辑  收藏 所属分类: Java

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