// 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();
  }
}

1、NTLM can be done with JCIFS and without HTTP. Only a few lines of code are required in the code of your servlet:

InetAddress ip = InetAddress.getByName(”192.168.0.1.”); // ip address of your windows controller
UniAddress myDomain = new UniAddress(ip);
NtlmPasswordAuthentication auth = new NtlmPasswordAuthentication(”MYDOMAIN”, “mylogin”, “mypasword”);
SmbSession.logon(myDomain, auth);

If an exception is triggered, the controller didn’t like the login and the password

2、Http方式下web.xml中filter的配置:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE web-app PUBLIC "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN" "http://java.sun.com/dtd/web-app_2_3.dtd">
<web-app>
 <display-name>WEB APP</display-name>
 <description>WEB APP description</description>
 <servlet>
  <servlet-name>ShowRequestHeaders</servlet-name>
  <servlet-class>coreservlets.ShowRequestHeaders</servlet-class>
 </servlet>
 <servlet-mapping>
  <servlet-name>ShowRequestHeaders</servlet-name>
  <url-pattern>/ShowRequestHeaders</url-pattern>
 </servlet-mapping>
  <filter>
    <filter-name>NtlmHttpFilter</filter-name>
    <filter-class>jcifs.http.NtlmHttpFilter</filter-class>

    <init-param>
        <param-name>jcifs.http.domainController</param-name>
        <param-value>192.168.10.1</param-value>
    </init-param>
  </filter>

  <filter-mapping>
    <filter-name>NtlmHttpFilter</filter-name>
    <url-pattern>/*</url-pattern>
  </filter-mapping>
 
</web-app>

//import java.text.*;
//import java.util.*;

public static String addDate(String day,int x)
  {
    SimpleDateFormat format=new SimpleDateFormat("yyyy/MM/dd");
    Date date = null;
    try
    {
      date = format.parse(day);
    }
    catch (ParseException ex)
    {
      ex.printStackTrace();
    }
    if (date==null) return "";
    Calendar cal=Calendar.getInstance();
    cal.setTime(date);
    cal.add(Calendar.DAY_OF_MONTH,x);
    date=cal.getTime();
    System.out.println("3 days after(or before) is "+format.format(date));
    cal=null;
    return format.format(date);
  }

建目录coreservlets,将两个servlets放在这个目录中,在coreservlet的上级目录
运行:
javac coreservlets/HelloServlet3.java



package coreservlets;

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

/** Simple servlet for testing the use of packages
 *  and utilities from the same package.
 *  <P>
 *  Taken from Core Servlets and JavaServer Pages 2nd Edition
 *  from Prentice Hall and Sun Microsystems Press,
 *  http://www.coreservlets.com/.
 *  &copy; 2003 Marty Hall; may be freely used or adapted.
 */

public class HelloServlet3 extends HttpServlet {
  public void doGet(HttpServletRequest request,
                    HttpServletResponse response)
      throws ServletException, IOException {
    response.setContentType("text/html");
    PrintWriter out = response.getWriter();
    String title = "Hello (3)";
    out.println(ServletUtilities.headWithTitle(title) +
                "<BODY BGCOLOR=\"#FDF5E6\">\n" +
                "<H1>" + title + "</H1>\n" +
                "</BODY></HTML>");
  }
}




package coreservlets;

import javax.servlet.*;
import javax.servlet.http.*;

/** Some simple timesavers. Note that most are static methods.
 *  <P>
 *  Taken from Core Servlets and JavaServer Pages 2nd Edition
 *  from Prentice Hall and Sun Microsystems Press,
 *  http://www.coreservlets.com/.
 *  &copy; 2003 Marty Hall; may be freely used or adapted.
 */

public class ServletUtilities {
  public static final String DOCTYPE =
    "<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.0 " +
    "Transitional//EN\">";

  public static String headWithTitle(String title) {
    return(DOCTYPE + "\n" +
           "<HTML>\n" +
           "<HEAD><TITLE>" + title + "</TITLE></HEAD>\n");
  }

  /** Read a parameter with the specified name, convert it
   *  to an int, and return it. Return the designated default
   *  value if the parameter doesn't exist or if it is an
   *  illegal integer format.
  */
 
  public static int getIntParameter(HttpServletRequest request,
                                    String paramName,
                                    int defaultValue) {
    String paramString = request.getParameter(paramName);
    int paramValue;
    try {
      paramValue = Integer.parseInt(paramString);
    } catch(NumberFormatException nfe) { // null or bad format
      paramValue = defaultValue;
    }
    return(paramValue);
  }

  public static double getDoubleParameter
                                 (HttpServletRequest request,
                                  String paramName,
                                  double defaultValue) {
    String paramString = request.getParameter(paramName);
    double paramValue;
    try {
      paramValue = Double.parseDouble(paramString);
    } catch(NumberFormatException nfe) { // null or bad format
      paramValue = defaultValue;
    }
    return(paramValue);
  }

  /** Replaces characters that have special HTML meanings
   *  with their corresponding HTML character entities.
   */
 
  // Note that Javadoc is not used for the more detailed
  // documentation due to the difficulty of making the
  // special chars readable in both plain text and HTML.
  //
  // Given a string, this method replaces all occurrences of
  //  '<' with '&lt;', all occurrences of '>' with
  //  '&gt;', and (to handle cases that occur inside attribute
  //  values), all occurrences of double quotes with
  //  '&quot;' and all occurrences of '&' with '&amp;'.
  //  Without such filtering, an arbitrary string
  //  could not safely be inserted in a Web page.

  public static String filter(String input) {
    if (!hasSpecialChars(input)) {
      return(input);
    }
    StringBuffer filtered = new StringBuffer(input.length());
    char c;
    for(int i=0; i<input.length(); i++) {
      c = input.charAt(i);
      switch(c) {
        case '<': filtered.append("&lt;"); break;
        case '>': filtered.append("&gt;"); break;
        case '"': filtered.append("&quot;"); break;
        case '&': filtered.append("&amp;"); break;
        default: filtered.append(c);
      }
    }
    return(filtered.toString());
  }

  private static boolean hasSpecialChars(String input) {
    boolean flag = false;
    if ((input != null) && (input.length() > 0)) {
      char c;
      for(int i=0; i<input.length(); i++) {
        c = input.charAt(i);
        switch(c) {
          case '<': flag = true; break;
          case '>': flag = true; break;
          case '"': flag = true; break;
          case '&': flag = true; break;
        }
      }
    }
    return(flag);
  }
}

/*
 字符串分拆函数
 
--调用示例
 select * from dbo.fsplit('a;adf;fd;ed;dh',';')
 select * from dbo.fsplit('a,,adf,,fd,,ed,,dh',',,')
邹建 2003.07*/

--检查函数是否存在
if exists (select * from dbo.sysobjects where id = object_id(N'[dbo].[fsplit]') and xtype in (N'FN', N'IF', N'TF'))
 drop function [dbo].[fsplit]
GO

--创建字符串分拆的函数
create function fsplit(
@str varchar(8000) --要分拆的字符串
,@spli varchar(10) --字符串分隔符
)
returns @re table(istr varchar(8000))
as
begin
 declare @i int,@splen int
 select @splen=len(@spli)
  ,@i=charindex(@spli,@str)
 while @i>0
 begin
  insert into @re values(left(@str,@i-1))
  select @str=substring(@str,@i+@splen,8000)
   ,@i=charindex(@spli,@str)
 end
 if @str<>'' insert into @re values(@str)
 return
end

select * from dbo.fsplit(123|abc|000|777','|')

在Windows编程中可以调用SetTimer在指定窗口安装定时器(Timer)，定时器可以在指定的时间间隔周期性回调用户指定的方法，用来执行周期性的任务，如果想取消定时器，可以调用KillTimer取消。但是在java标准包里中并没有这种类。下面介绍的这个类包可以实现上述功能。

下面是接口，需要支持定时器功能的类要实现这个接口：

TimerClient.java

package com.ly.util;

/**
 * TimerClient Interface
 *
 * @version 1.0, 8 October 1995
 *
 */
public interface TimerClient
{
  void timerEvent(int id);
}

下面是定时器的实现，包括三个类：TimerCtl,TimerTask,TimerTasks。其中TimerTask用来描述定时器信息。TimerTasks是一个TimerTask的列表，这样我们就可以同时在一个应用中安插多个定时器。TimerCtl是定时器控制类，是个线程，不停地检查TimerTasks中是否有TimerTask到期，要是有TimerTask到达指定的时间，则回调TimerTask指定的TimerClient的timerEvent接口。

TimerCtl.java

package com.ly.util;

import java.util.Vector;
import java.util.Enumeration;
//import com.borland.jb.util.Diagnostic;

/**
 * Timer Component
 *
 * Note:
 *  - The successful operation of this timer requires clients to execute simple, short
 *    code snippets when called back by the engine.  Otherwise the queue's delivery
 *    mechanism will be held up
 *
 * Further work:
 *  - When Thread.Interrupt is implemented we can switch from the busy wait model to
 *    the calculated wait model.  Without the interrupt the thread waits for the
 *    calculated interval before waking up.  This is a problem if another shorter
 *    request arrives.  For now we'll assume the minimum resolution of the timer is
 *    100ms.
 *
 * @version 1.0, 2 October 1995
 *
 */
public class TimerCtl
{
  static TimerTasks timerTasks;

  public TimerCtl() {
  }

  /*
  * Start a timer running
  */
  public static void startTimer(TimerClient client, int eventId, long delay, boolean repeat) {
    // create the timer if necessary
    if (timerTasks == null) {
      timerTasks = new TimerTasks();
      timerTasks.start();
    }

    //Diagnostic.out.println("TIMER: startTimer"+eventId);

    // add the new task to the queue
    timerTasks.add(client, eventId, delay, repeat);
  }

  /*
  * Stop a timer
  */
  public static void stopTimer(TimerClient client, int eventId) {
    //Diagnostic.out.println("TIMER: stopTimer"+eventId);
    if(timerTasks != null)
        timerTasks.end(client, eventId);
  }
}

class TimerTasks extends Thread
{
  Vector tasks = new Vector();
  boolean suspended = false;
  boolean sleeping = false;

  /**
   * Thread task runner
   */
  public void run() {
    // Loop forever
    while (true) {
      long sleepTime = 0;

      // Ensure that the tasks class is protected
      synchronized (tasks) {
        //Diagnostic.out.println("TIMER: Tick");

        // Scan the job list for any jobs which may fire.
        // Mark one-shot jobs for deletion
        // Calculate the maximum time we can sleep for
        sleepTime = scan();

        // Delete DeletePending jobs.  DeletePending jobs result from one-shots which have
        // been sent, and repeat jobs which have been cancelled.  Jobs may have been
        // cancelled during the Scan process.
        purge();
      }

      // Suspend timer if necessary
      if (tasks.size() == 0) {
        //Diagnostic.out.println("TIMER: Suspend");
        try {
          synchronized(this) {
            suspended = true;
            wait();
          }
        }
        catch (InterruptedException e) {
        }
      }
      else {
        //Diagnostic.out.println("TIMER: Suggested Sleeping for "+sleepTime);
        if (sleepTime >= 0) {
          try {
            sleeping = true;
            sleep(sleepTime);
            sleeping = false;
          }
          catch (InterruptedException i) {
            //Diagnostic.out.println("TIMER: Caught me napping");
          }
        }
      }
    }
  }

  /**
   * Add a new task
   */
  public void add(TimerClient client, int eventId, long delay, boolean repeat) {
    TimerTask t = new TimerTask(client, eventId, delay, repeat);

    synchronized (tasks) {
      tasks.addElement((Object)t);
    }

    // Want instant response - wake the thread if it's napping
    // unfortunately the interrupt() method is not working
//    if (sleeping)
//      interrupt();

    if (suspended) {
      synchronized(this) {
        notify();
        //Diagnostic.out.println("TIMER: Resume");
        suspended = false;
      }
    }
  }

  /**
   * Find the job and mark it for deletion
   */
  public void end(TimerClient client, int eventId) {
    synchronized (tasks) {
      for (int i = 0; i < tasks.size(); i++) {
        TimerTask t = (TimerTask)tasks.elementAt(i);

        //if (!t.deletePending && t.client == client && t.eventId == eventId)
        if (t.deletePending == false && t.client == client && t.eventId == eventId) {
          // JPBS - if we don't reset 'repeat', deletePending will be set again
          t.repeat = false;
          t.deletePending = true;
          break;
        }
      }
    }
  }

  /**
   * Clear out all the dead wood
   */
  void purge() {
    for (int i = 0; i < tasks.size(); i++) {
      TimerTask t = (TimerTask)tasks.elementAt(i);

      if (t.deletePending) {
        //Diagnostic.out.println("TIMER: purged");

        tasks.removeElementAt(i);
        i--;
      }
    }
  }

  long scan() {
    // The value added to the current time determines the MAX time until
    // the next scan
    // This is 100 now since thread.interrupt() is not implemented
    long nextTime = System.currentTimeMillis() + 100;

    for (int i = 0; i < tasks.size(); i++) {
      TimerTask t = (TimerTask)tasks.elementAt(i);

      // if not already deletePending, test (and possibly send the event)
      // as a result, the job may be flagged for deletion.
      // May also be a non-repeating job and so require self deletion
      if (!t.deletePending)
        t.test();

      // if the task didn't get deleted - see what it contributes to the time
      if (!t.deletePending)
        nextTime = Math.min(nextTime, t.timeNext);

      //Diagnostic.out.println("TIMER: Scanning "+t.eventId+" "+(t.deletePending == true ? "DEL" : ""));
    }

    return nextTime - System.currentTimeMillis();
  }
}

class TimerTask
{
  TimerClient client;
  int         eventId;

  long        timePrev;
  long        timeDelay;
  long        timeNext;

  boolean repeat;
  boolean deletePending;

  public TimerTask(TimerClient client, int eventId, long timeDelay, boolean repeat) {
    this.client = client;
    this.eventId = eventId;
    this.timeDelay = timeDelay;
    this.repeat = repeat;

    // schedule the next click - now + delay
    timeNext = System.currentTimeMillis() + timeDelay;
    deletePending = false;

    //Diagnostic.out.println("TIMER: Adding New Task");
  }

  public void test() {
    if (System.currentTimeMillis() >= timeNext) {
      //Diagnostic.out.println("TIMER: fire");

      // Fire the event
      client.timerEvent(eventId);

      // Update the next time
      timeNext = System.currentTimeMillis() + timeDelay;

      deletePending = !repeat;
    }
  }
}

　
下面是一个使用例子

TimerTest.java

package com.ly.util;

import java.io.*;
import java.util.*;
import com.ly.util.*;

/**
* Title:
* Description:
* Copyright: Copyright (c) 2001
* Company: http://dozb.blogchina.com
* @author dozb
* @version 1.0
*/
public class TimerTest implements TimerClient{
public TimerTest()
{
starttime();
}
public void timerEvent(int id)
{
System.out.println("timerEvent...");
}
public void starttime()
{
TimerCtl.startTimer(this,1,5*1000,true);
}
public void stoptime()
{
TimerCtl.stopTimer(this,1);
}

public static void main(String[] args)
{
new TimerTest();
try
{
Thread.sleep(200000);
}catch(Exception e)
{
}

}
}

通过这种方式，可以高效地使用socket通讯，在异步socket版本没有发布以前，不失是一种解决问题的方法。:)