// Listing 2: controller.java

protected final void doPost(
    HttpServletRequest request,
    HttpServletResponse response) {

    // begining codes
    //--用户已通过身份验证
    if (((String) request.getAttribute("login")).equals
       ("login success")) {
        ArrayList actionreport = new ArrayList();
        actionreport.add("Correct Password");
        session.setAttribute("actionreport", actionreport);
        nextPage = "success.jsp";
    }
    if (dispatch) {
        RequestDispatcher rd =
            getServletContext().getRequestDispatcher(nextPage);
        rd.forward(request, response);
    } else {

        session.invalidate();

    }
    // ending codes
}

问题：JavaBean的一个写文件方法，独立调试正常。但移到Struts下，通过Action调用时，

抛出异常。

原因：文件路径问题

解决方法：

1.修改原来JavaBean里带前缀路径的文件---"resources/users.properties"

为"users.properties"

2.将struts框架下的源文件users.properties，直接移到src下

3.重新编译，部署

4.运行这个注册组件成功后，可以到$服务器主目录$/bin下，查看这个已经写过的

users.properties文件

以上问题，曾尝试将resources/user.properite改为绝对路径"d:/users.properties"，

或改为相对路径"/resources/properties"，或直接向JavaBean中传入路径参数path，

path=request.getRealPath("")(或request.getContextPath)等，均没有调试成功。

故记录下来，希望其它网友遇到时，不必再做这样的重复劳动。

附：

1.Action中调用方法:

UserDirectory.getInstance().setUser(userName,password1);

2.JavaBean的缩略代码：

UserDirectory.java

import java.io.IOException;
import java.io.FileOutputStream;
import java.util.Enumeration;
import java.util.Properties;

public class UserDirectory {
 private static final String UserDirectoryFile = "users.properties";
 private static final String UserDirectoryHeader = "${user}=${password}";

 public static UserDirectory getInstance() throws UserDirectoryException {
  if (null == userDirectory) {
   userDirectory = new UserDirectory();
  }
   return userDirectory;
 }
 
  public void setUser(String userId, String password) throws
   UserDirectoryException {
   if ( (null == userId) || (null == password)) {
    throw new UserDirectoryException();
   }try {
    p.put(fixId(userId), password);
    p.store(new FileOutputStream(UserDirectoryFile),UserDirectoryHeader);
   }catch (IOException e) {
    throw new UserDirectoryException();
   }
  }
 }

• char charAt(int index)

  returns the character at the specified location.

• int compareTo(String other)

  returns a negative value if the string comes before other in dictionary order, a positive value if the string comes after other in dictionary order, or 0 if the strings are equal.

• boolean endsWith(String suffix)

  returns true if the string ends with suffix.

• boolean equals(Object other)

  returns true if the string equals other.

• boolean equalsIgnoreCase(String other)

  returns true if the string equals other, except for upper/lowercase distinction.

• int indexOf(String str)

• int indexOf(String str, int fromIndex)

  return the start of the first substring equal to str, starting at index 0 or at fromIndex.

• int lastIndexOf(String str)

• int lastIndexOf(String str, int fromIndex)

  return the start of the last substring equal to str, starting at the end of the string or at fromIndex.

• int length()

  returns the length of the string.

• String replace(char oldChar, char newChar)

  returns a new string that is obtained by replacing all characters oldChar in the string with newChar.

• boolean startsWith(String prefix)

  returns true if the string begins with prefix.

• String substring(int beginIndex)

• String substring(int beginIndex, int endIndex)

  return a new string consisting of all characters from beginIndex until the end of the string or until endIndex (exclusive).

• String toLowerCase()

  returns a new string containing all characters in the original string, with uppercase characters converted to lower case.

• String toUpperCase()

  returns a new string containing all characters in the original string, with lowercase characters converted to upper case.

• String trim()

  returns a new string by eliminating all leading and trailing spaces in the original string.

字符串与基本数据类型的转换间的转换必须使用JSP中的对象函数
Boolean.getBoolean(String)
Byte.parseByte(String)
Short.parseShort(String)
Integer.parseInt(String)
Long.parseLong(String)
Float.parseDouble(String)
Double.parseDouble(String)
String.valueOF(数据)


Array

eg: 

 int[] smallPrimes = {2, 3, 5, 7, 11, 13};
  int[] luckyNumbers = {1001, 1002, 1003, 1004, 1005, 1006, 1007};
  System.arraycopy(smallPrimes, 2, luckyNumbers, 3, 3);
  for (int i = 0; i < luckyNumbers.length; i++)
     System.out.println(i + ": " + luckyNumbers[i]);

1、Message.java
public class Message {

 public static void main(String[] args) {
    if (args[0].equals("-h"))
          System.out.print("Hello,");
       else if (args[0].equals("-g"))
          System.out.print("Goodbye,");
       // print the other command line arguments
       for (int i = 1; i < args.length; i++)
          System.out.print(" " + args[i]);
       System.out.println("!");

 }
}

test:
java Message -g cruel world



import java.util.*;
import javax.swing.*;
public class FirstSample {

 public static void main(String[] args) {
       String input = JOptionPane.showInputDialog
          ("How many numbers do you need to draw?");
       int k = Integer.parseInt(input);

       input = JOptionPane.showInputDialog
          ("What is the highest number you can draw?");
       int n = Integer.parseInt(input);

       // fill an array with numbers 1 2 3 . . . n
       int[] numbers = new int[n];
       for (int i = 0; i < numbers.length; i++)
       {    numbers[i] = i + 1;
       System.out.println(numbers[i]);
       }
       // draw k numbers and put them into a second array

       int[] result = new int[k];
       for (int i = 0; i < result.length; i++)
       { 
          // make a random index between 0 and n - 1
          int r = (int)(Math.random() * n);

          // pick the element at the random location
          result[i] = numbers[r];

          // move the last element into the random location
          numbers[r] = numbers[n - 1];
          n--;
       }

       // print the sorted array

       Arrays.sort(result);
       System.out.println
          ("Bet the following combination. It'll make you rich!");
       for (int i = 0; i < result.length; i++)
          System.out.println(result[i]);

       System.exit(0);

 }
}

The include Directive

The following is the syntax for the include directive:

<%@ include file="relativeURL" %>

As you can see the directive accepts a single file attribute that is used to indicate the resource whose content is to be included in the declaring JSP. The file attribute is interpreted as a relative URL; if it starts with a slash it's interpreted as relative to the context of the web application (namely a context-relative path), otherwise it's interpreted as relative to the path of the JSP that contains the include directive (namely a page relative path). The included file may contain either static content, such as HTML or XML, or another JSP page.

For example:
<%@ include file="/copyright.html"%>


Let's consider a real-world example of such a templating mechanism that utilizes the include directive to provide a consistent page layout for a web application.

Consider the following two JSP pages:

Header.jsp
    <html>
      <head><title>A Very Simple Example</title></head>
      <body style="font-family:verdana,arial;font-size:10pt;">
        <table width="100%" height="100%">
          <tr bgcolor="#99CCCC">
            <td align="right" height="15%">Welcome to this example...</td>
          </tr>
          <tr>
            <td height="75%">

Footer.jsp
           </td>
         </tr>
         <tr bgcolor=" #99CC99">
           <td align="center" height="10%">Copyright ACompany.com 2003</td>
         </tr>
       </table>
     </body>
   </html>

As you can see, Header.jsp declares the starting elements of an HTML table that is to be 100 percent of the size of the page and has two rows, whereas Footer.jsp simply declares the closing elements for the table. Used separately, either JSP will result in partial HTML code that will look very strange to a user but when they're combined using the include directive it's easy to create consistent pages as part of a web application.

Let's see just how simple this basic template mechanism is to use:

Content.jsp
    <%@ include file='./Header.jsp'%>
    <p align="center">The Content Goes Here...!!!</p>
    <%@ include file='./Footer.jsp'%>

2、
date.jsp
<html>
  <body>
    <h2>Greetings!</h2>
 <P>The current time is <%=new java.util.Date()%> precisely
  </body>
</html>

3、
dateBean.jsp
<html>
    <head><title>Professional JSP, 3rd Edition</title></head>
    <body style="font-family:verdana;font-size:10pt;">
        <jsp:useBean id="date" class="com.apress.projsp20.ch01.DateFormatBean"/>
        <h2>Today's date is <%= date.getDate() %></h2>
    </body>
</html>

或：
dateBean_getProperty.jsp
<html>
    <head><title>Professional JSP, 3rd Edition</title></head>
    <body style="font-family:verdana;font-size:10pt;">
        <jsp:useBean id="date" class="com.apress.projsp20.ch01.DateFormatBean"/>
        <h2>Today's date is <jsp:getProperty name="date" property="date"/></h2>
    </body>
</html>

dateBean_setProperty.jsp
<html>
    <head><title>Professional JSP, 3rd Edition</title></head>
    <body style="font-family:verdana;font-size:10pt;">
        <jsp:useBean id="date" class="com.apress.projsp20.ch01.DateFormatBean"/>
        <jsp:setProperty name="date" property="format"
                         value="EEE, d MMM yyyy HH:mm:ss z"/>
        <h2>Today's date is <jsp:getProperty name="date" property="date"/></h2>
    </body>
</html>

其中DateFormatBean.java:
   package com.apress.projsp20.ch01;

    import java.util.Date;
    import java.text.*;

    public class DateFormatBean {
      private DateFormat dateFormat;
      private Date date;

      public DateFormatBean() {
        dateFormat = DateFormat.getInstance();
        date = new Date();
      }

      public String getDate() {
        return dateFormat.format(date);
      }

      public void setDate(Date date) {
        this.date = date;
      }

      public void setFormat(String format) {
        this.dateFormat = new SimpleDateFormat(format);
      }
    }
例：SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");

DBPhoneLookupReuse.java
import java.io.*;
import java.sql.*;
import javax.servlet.*;
import javax.servlet.http.*;

public class DBPhoneLookupReuse extends HttpServlet {

  private Connection con = null;

  public void init() throws ServletException {
    try {
      // Load (and therefore register) the Sybase driver
      Class.forName("com.jnetdirect.jsql.JSQLDriver");
      con = DriverManager.getConnection(
        "jdbc:JSQLConnect://127.0.0.1/database=JAAS", "sa", "db_password");
    }
    catch (ClassNotFoundException e) {
      throw new UnavailableException("Couldn't load database driver");
    }
    catch (SQLException e) {
      throw new UnavailableException("Couldn't get db connection");
    }
  }

  public void doGet(HttpServletRequest req, HttpServletResponse res)
                               throws ServletException, IOException {
    res.setContentType("text/html");
    PrintWriter out = res.getWriter();

    out.println("<HTML><HEAD><TITLE>Phonebook</TITLE></HEAD>");
    out.println("<BODY>");

    HtmlSQLResult result =
      new HtmlSQLResult("SELECT UserName,Password FROM Users", con);

    // Display the resulting output
    out.println("<H2>Users:</H2>");
    out.println(result);
    out.println("</BODY></HTML>");
  }

  public void destroy() {
    // Clean up.
    try {
      if (con != null) con.close();
    }
    catch (SQLException ignored) { }
  }
}

HtmlSQLResult.java
import java.sql.*;

public class HtmlSQLResult {
  private String sql;
  private Connection con;

  public HtmlSQLResult(String sql, Connection con) {
    this.sql = sql;
    this.con = con;
  }

  public String toString() {  // can be called at most once
    StringBuffer out = new StringBuffer();

    // Uncomment the following line to display the SQL command at start of table
    // out.append("Results of SQL Statement: " + sql + "<P>\n");

    try {
      Statement stmt = con.createStatement();

      if (stmt.execute(sql)) {
        // There's a ResultSet to be had
        ResultSet rs = stmt.getResultSet();
        out.append("<TABLE>\n");

        ResultSetMetaData rsmd = rs.getMetaData();

        int numcols = rsmd.getColumnCount();
  
        // Title the table with the result set's column labels
        out.append("<TR>");
        for (int i = 1; i <= numcols; i++)
          out.append("<TH>" + rsmd.getColumnLabel(i));
        out.append("</TR>\n");

        while(rs.next()) {
          out.append("<TR>");  // start a new row
          for(int i = 1; i <= numcols; i++) {
            out.append("<TD>");  // start a new data element
            Object obj = rs.getObject(i);
            if (obj != null)
              out.append(obj.toString());
            else
              out.append("&nbsp;");
            }
          out.append("</TR>\n");
        }

        // End the table
        out.append("</TABLE>\n");
      }
      else {
        // There's a count to be had
        out.append("<B>Records Affected:</B> " + stmt.getUpdateCount());
      }
    }
    catch (SQLException e) {
      out.append("</TABLE><H1>ERROR:</H1> " + e.getMessage());
    }
  
    return out.toString();
  }
}