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java的常用函数1

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/**
     * 将某个日期以固定格式转化成字符串
     *
     *
@param date
     *
@return String
    
*/
   
public static String dateToStr(java.util.Date date)
    {
        SimpleDateFormat sdf
= new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
        String str
= sdf.format(date);
       
return str;
    }

**
     * 判断任意一个整数是否素数
     *
     *
@param n
     *
@return boolean
    
*/
   
public static boolean isPrimes(int n)
    {
       
for (int i = 2; i <= Math.sqrt(n); i++)
        {
           
if (n % i == 0)
            {
               
return false;
            }
        }
       
return true;
    }

 

**
     * 获得任意一个整数的阶乘,递归
      *
     *
@param n
     *
@return n!
    
*/
   
public static int factorial(int n)
    {
       
if (n == 1)
        {
           
return 1;
        }
       
return n * factorial(n - 1);
    }

/**
     * 将指定byte数组以16进制的形式打印到控制台
     *
     *
@param hint
     *            String
     *
@param b
     *            byte[]
     *
@return void
    
*/
   
public static void printHexString(String hint, byte[] b)
    {
        System.out.print(hint);
       
for (int i = 0; i < b.length; i++)
        {
            String hex
= Integer.toHexString(b[i] & 0xFF);
           
if (hex.length() == 1)
            {
                hex
= '0' + hex;
            }
            System.out.print(hex.toUpperCase()
+ " ");
        }
        System.out.println(
"");
    }

 

package net.java2000.tools;

/**
* Title:        java Bean 工具
* Description:
* Copyright:    Copyright (c) 2001
* Company:      java世纪网
http://www.java2000.net
*
@author 赵学庆
*
@version 1.0
*/
import java.util.*;
import java.util.regex.Pattern;

public class StrTools {
 
/**
   * 分割字符串
   *
   *
@param str String 原始字符串
   *
@param splitsign String 分隔符
   *
@return String[] 分割后的字符串数组
  
*/
  @SuppressWarnings(
"unchecked")
 
public static String[] split(String str, String splitsign) {
   
int index;
   
if (str == null || splitsign == null)
     
return null;
    ArrayList al
= new ArrayList();
   
while ((index = str.indexOf(splitsign)) != -1) {
      al.add(str.substring(
0, index));
      str
= str.substring(index + splitsign.length());
    }
    al.add(str);
   
return (String[]) al.toArray(new String[0]);
  }

 
/**
   * 替换字符串
   *
   *
@param from String 原始字符串
   *
@param to String 目标字符串
   *
@param source String 母字符串
   *
@return String 替换后的字符串
  
*/
 
public static String replace(String from, String to, String source) {
   
if (source == null || from == null || to == null)
     
return null;
    StringBuffer bf
= new StringBuffer("");
   
int index = -1;
   
while ((index = source.indexOf(from)) != -1) {
      bf.append(source.substring(
0, index) + to);
      source
= source.substring(index + from.length());
      index
= source.indexOf(from);
    }
    bf.append(source);
   
return bf.toString();
  }

 
/**
   * 替换字符串,能能够在HTML页面上直接显示(替换双引号和小于号)
   *
   *
@param str String 原始字符串
   *
@return String 替换后的字符串
  
*/
 
public static String htmlencode(String str) {
   
if (str == null) {
     
return null;
    }

   
return replace("\"", """, replace("<", "<", str));
  }

 
/**
   * 替换字符串,将被编码的转换成原始码(替换成双引号和小于号)
   *
   *
@param str String
   *
@return String
  
*/
 
public static String htmldecode(String str) {
   
if (str == null) {
     
return null;
    }

   
return replace(""", "\"", replace("<", "<", str));
  }

 
private static final String _BR = "
";

 
/**
   * 在页面上直接显示文本内容,替换小于号,空格,回车,TAB
   *
   *
@param str String 原始字符串
   *
@return String 替换后的字符串
  
*/
 
public static String htmlshow(String str) {
   
if (str == null) {
     
return null;
    }

    str
= replace("<", "<", str);
    str
= replace(" ", " ", str);
    str
= replace("\r\n", _BR, str);
    str
= replace("\n", _BR, str);
    str
= replace("\t", "    ", str);
   
return str;
  }

 
/**
   * 返回指定字节长度的字符串
   *
   *
@param str String 字符串
   *
@param length int 指定长度
   *
@return String 返回的字符串
  
*/
 
public static String toLength(String str, int length) {
   
if (str == null) {
     
return null;
    }
   
if (length <= 0) {
     
return "";
    }
   
try {
     
if (str.getBytes("GBK").length <= length) {
       
return str;
      }
    }
catch (Exception ex) {
    }
    StringBuffer buff
= new StringBuffer();

   
int index = 0;
   
char c;
    length
-= 3;
   
while (length > 0) {
      c
= str.charAt(index);
     
if (c < 128) {
        length
--;
      }
else {
        length
--;
        length
--;
      }
      buff.append(c);
      index
++;
    }
    buff.append(
"...");
   
return buff.toString();
  }

 
/**
   * 判断是否为整数
   *
   *
@param str 传入的字符串
   *
@return 是整数返回true,否则返回false
  
*/
 
public static boolean isInteger(String str) {
    Pattern pattern
= Pattern.compile("^[-\\+]?[\\d]*$");
   
return pattern.matcher(str).matches();
  }

 
/**
   * 判断是否为浮点数,包括double和float
   *
   *
@param str 传入的字符串
   *
@return 是浮点数返回true,否则返回false
  
*/
 
public static boolean isDouble(String str) {
    Pattern pattern
= Pattern.compile("^[-\\+]?[.\\d]*$");
   
return pattern.matcher(str).matches();
  }

 
/**
   * 判断输入的字符串是否符合Email样式.
   *
   *
@param str 传入的字符串
   *
@return 是Email样式返回true,否则返回false
  
*/
 
public static boolean isEmail(String str) {
    Pattern pattern
= Pattern.compile("^\\w+([-+.]\\w+)*@\\w+([-.]\\w+)*\\.\\w+([-.]\\w+)*$");
   
return pattern.matcher(str).matches();
  }

 
/**
   * 判断输入的字符串是否为纯汉字
   *
   *
@param str 传入的字符窜
   *
@return 如果是纯汉字返回true,否则返回false
  
*/
 
public static boolean isChinese(String str) {
    Pattern pattern
= Pattern.compile("[\u0391-\uFFE5]+$");
   
return pattern.matcher(str).matches();
  }

 
/**
   * 是否为空白,包括null和""
   *
   *
@param str
   *
@return
  
*/
 
public static boolean isBlank(String str) {
   
return str == null || str.trim().length() == 0;
  }

 
/**
   * 判断是否为质数
   *
   *
@param x
   *
@return
  
*/
 
public static boolean isPrime(int x) {
   
if (x <= 7) {
     
if (x == 2 || x == 3 || x == 5 || x == 7)
       
return true;
    }
   
int c = 7;
   
if (x % 2 == 0)
     
return false;
   
if (x % 3 == 0)
     
return false;
   
if (x % 5 == 0)
     
return false;
   
int end = (int) Math.sqrt(x);
   
while (c <= end) {
     
if (x % c == 0) {
       
return false;
      }
      c
+= 4;
     
if (x % c == 0) {
       
return false;
      }
      c
+= 2;
     
if (x % c == 0) {
       
return false;
      }
      c
+= 4;
     
if (x % c == 0) {
       
return false;
      }
      c
+= 2;
     
if (x % c == 0) {
       
return false;
      }
      c
+= 4;
     
if (x % c == 0) {
       
return false;
      }
      c
+= 6;
     
if (x % c == 0) {
       
return false;
      }
      c
+= 2;
     
if (x % c == 0) {
       
return false;
      }
      c
+= 6;
    }
   
return true;
  }

 
public static void main(String[] args) {
    String[] numbers
= { "12345", "-12345", "123.45", "-123.45", ".12345", "-.12345", "a12345", "12345a", "123.a45" };
   
for (String str : numbers) {
      System.out.println(str
+ "=" + isInteger(str) + " " + isDouble(str));
    }

    String[] emails
= { "1@2.com", "1.2@3.com", "1@3.4.5.com" };
   
for (String str : emails) {
      System.out.println(str
+ "=" + isEmail(str));
    }
    String[] chineses
= { "中国", "1中国", "中国1", "1中国2", "中1国" };
   
for (String str : chineses) {
      System.out.println(str
+ "=" + isChinese(str));
    }
  }
}

 

/* * Db.java
Created on 2007年8月20日, 上午 8:37
*/
import java.io.*;
import java.sql.*;
import java.util.Properties;
public class Db {
   
private String driver;
   
private String url;
   
private String user;
   
private String password;
   
private Connection conn;
   
private Statement stm;
   
private ResultSet rs;
   
public Db(){
       
this("DBConf.properties");
    }
   
public Db(String conf) {
        loadProperties(conf);
        setConn();
    }
   
public Connection getConn(){
       
return this.conn;
    }
 
//handle the properties file to get the informations for connection
    private void loadProperties(String conf){
        Properties props
= new Properties();
       
try {
            props.load(
new FileInputStream(conf));
        }
catch (FileNotFoundException e) {
            e.printStackTrace();
        }
catch (IOException e) {
            e.printStackTrace();
        }
       
this.driver = props.getProperty("driver");
       
this.url = props.getProperty("url");
       
this.user = props.getProperty("user");
       
this.password = props.getProperty("password");
    }
   
//implement the Connection
    private void setConn(){
       
try {
            Class.forName(driver);
           
this.conn = DriverManager.getConnection(url,user,password);
        }
catch(ClassNotFoundException classnotfoundexception) {
              classnotfoundexception.printStackTrace();
            System.err.println(
"db: " + classnotfoundexception.getMessage());
        }
catch(SQLException sqlexception) {
            System.err.println(
"db.getconn(): " + sqlexception.getMessage());
        }
    }
      
public void doInsert(String sql) {
       
try {
            Statement statement
= conn.createStatement();
           
int i = stm.executeUpdate(sql);
        }
catch(SQLException sqlexception) {
            System.err.println(
"db.executeInset:" + sqlexception.getMessage());
        }
    }
   
public void doDelete(String sql) {
       
try {
            stm
= conn.createStatement();
           
int i = stm.executeUpdate(sql);
        }
catch(SQLException sqlexception) {
            System.err.println(
"db.executeDelete:" + sqlexception.getMessage());
        }
    }
   
public void doUpdate(String sql) {
       
try {
            stm
= conn.createStatement();
           
int i = stm.executeUpdate(sql);
        }
catch(SQLException sqlexception) {
            System.err.println(
"db.executeUpdate:" + sqlexception.getMessage());
        }
    }
   
   
public ResultSet doSelect(String sql) {
       
try {
            stm
= conn.createStatement(java.sql.ResultSet.TYPE_SCROLL_INSENSITIVE,java.sql.ResultSet.CONCUR_READ_ONLY);
            rs
= stm.executeQuery(sql);
        }
catch(SQLException sqlexception) {
            System.err.println(
"db.executeQuery: " + sqlexception.getMessage());
        }
       
return rs;
    }
   
public static void main(String[] args){
       
try{
            Db db
= new Db();
            Connection conn
= db.getConn();
           
if(conn != null && !conn.isClosed()) {
                System.out.println(
"連結成功");
                ResultSet rs
= db.doSelect("select * from content");
               
while(rs.next()){
                    System.out.println(rs.getString(
1)+":"+rs.getString(2)+":"+rs.getString(3));
                  }
                rs.close();
                conn.close();
            }
        }
catch(SQLException e) {
            e.printStackTrace();
        }
    } 
}




DBConf.properties:
driver=oracle.jdbc.driver.OracleDriver
url=jdbc:oracle:thin:@tdt151:1521:train
user=XX
password=XX

 

posted on 2009-06-10 21:02 rrong_m 阅读(179) 评论(0)  编辑  收藏 所属分类: java

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