一个老问题，但我始终没有彻底解决。还请大侠帮帮我，先谢过了。[分不够可以再加]

Question

可能是close把ServerOpen对象给清除了吧！！！

Answer 1

你程序的问题是，线程是不可以重入的。所以你在线程退出后在start是不行的。
所以这样就行了。
class ServerFrame extends JFrame implements ActionListener
{    public ServerFrame()
    {    JPanel p=new JPanel();
        startButton =new JButton("´ò¿ª");
        p.add(startButton);
        startButton.addActionListener(this);
        getContentPane().add(p,"South");
        textArea=new JTextArea(8,40);
        scrollPane=new JScrollPane(textArea);
        getContentPane().add(scrollPane,"Center");
        
        setTitle("·þÎñÆ÷");
        setSize(500,300);
        
        
        
        addWindowListener(new WindowAdapter()
            {    public void windowClosing(WindowEvent e)
                {    System.exit(0);
                }
            });
    }
    public void actionPerformed(ActionEvent evt)
    {    
        Object source=evt.getSource();
        if (source==startButton)
        {    
            if (startButton.getText()!="´ò¿ª")
            {
                startButton.setText("´ò¿ª");
                ServerOpen.shutoff();
            }
            else
            {    
                startButton.setText("¹Ø±Õ");
                ServerOpen=new ServerHandler();
                ServerOpen.start();
            }
        }
    }    private JButton startButton;
    private JScrollPane scrollPane;
    private JTextArea textArea;
    private ServerHandler ServerOpen;
    private Thread newHandlerThread;
}

Answer 2

线程原来是不可以重入的。你的方法我试过了，可以打开关闭控制。不过还有一个问题请教你，在点击了关闭之后，服务器的socket端口的确是关闭了，可为什么原来已经打开的线程，还是处于打开状态。例如我将ThreadedEchoHandler方法加入后，点击关闭按钮，原来已经打开的socket还是可以通信，怎样做到将原来的一起关闭呢？import java.io.*;
import java.net.*;
import java.util.*;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;public class Clk_Server2
{ public static void main(String[] args)
{
JFrame frame=new ServerFrame();
frame.show();
}
}class ServerFrame extends JFrame implements ActionListener
{    public ServerFrame()
    {    JPanel p=new JPanel();
        startButton =new JButton("打开");
        p.add(startButton);
        startButton.addActionListener(this);
        getContentPane().add(p,"South");
        textArea=new JTextArea(8,40);
        scrollPane=new JScrollPane(textArea);
        getContentPane().add(scrollPane,"Center");
        
        setTitle("服务器");
        setSize(500,300);
        
        
        
        addWindowListener(new WindowAdapter()
            {    public void windowClosing(WindowEvent e)
                {    System.exit(0);
                }
            });
    }
    public void actionPerformed(ActionEvent evt)
    {    
        Object source=evt.getSource();
        if (source==startButton)
        {    
            if (startButton.getText()!="打开")
            {
                startButton.setText("打开");
                ServerOpen.shutoff();
            }
            else
            {    
                startButton.setText("关闭");
ServerOpen=new ServerHandler();
                ServerOpen.start();
            }
        }
    }    private JButton startButton;
    private JScrollPane scrollPane;
    private JTextArea textArea;
    private ServerHandler ServerOpen;
    private Thread newHandlerThread;
}  class ServerHandler extends Thread 
//implements Runnable 
{
private static final int SERVER_PORT=8189;
private static final int MAX_CLIENTS=100;
private boolean keepRunning=false;
private ServerSocket listenSocket=null;

    public void run() 
{ Socket clientSocket = null;
int i = 1;
try
{
listenSocket=new ServerSocket(SERVER_PORT,MAX_CLIENTS);
while (true)
{ try
{
sleep(5);
}
catch(InterruptedException e)
{ System.err.println("Sleep InterruptedException : "+e);
}
         // Accept a new client.
    clientSocket = listenSocket.accept();
System.out.println("Spawning " + i);
             new ThreadedEchoHandler(clientSocket, i).start();
             i++;
          }
}
catch(IOException excpt)
{ System.err.println("Unable to listen on port "+SERVER_PORT+" : "+excpt);
//shutoff();
//return;
}
    }

protected void status(boolean Status) 
{
        keepRunning = Status;
}
public void shutoff() 
{ try
{ //System.out.println("Socket Closed _shutoff.");
listenSocket.close();
}
catch(IOException excpt) 
{
         System.err.println("Failed I/O: "+ excpt);
       }
}
}class ThreadedEchoHandler extends Thread
{  public ThreadedEchoHandler(Socket i, int c)
   { incoming = i; counter = c; }   public void run()
   {  try
      {  BufferedReader in = new BufferedReader
            (new InputStreamReader(incoming.getInputStream()));
         PrintWriter out = new PrintWriter
            (incoming.getOutputStream(), true /* autoFlush */);         out.println( "Hello! Enter BYE to exit." );         boolean done = false;
         while (!done)
         {  String str = in.readLine();
            if (str == null) done = true;
            else
            {  out.println("Echo (" + counter + "): " + str);               if (str.trim().equals("BYE"))
                  done = true;
            }
         }
         incoming.close();
      }
      catch (Exception e)
      {  System.out.println(e);
      }
   }   private Socket incoming;
   private int counter;
}

Answer 3

to:lusxiao(lusxiao)，分我一定会给你的，只不过不想让帖子这么快消失。3q!

Answer 4

因为你只是关闭了listenSocket，但clientSocket并没有被关闭。所以当点了关闭按钮后客户端还可以和ThreadedEchoHandler通信。
解决方法：
　　关闭clientSocket，这样你就要保存每个客户端的clientSocket，一种方法是用clientSocket数组实现。
　　杀线程（不推荐）。
明白?

Answer 5

一种实现方法：
class ServerHandler extends Thread 
//implements Runnable 
{
   private static final int SERVER_PORT=8189;
   private static final int MAX_CLIENTS=100;
   private boolean keepRunning=false;
   private ServerSocket listenSocket=null;
   private Vector clientSocketVect=new Vector(MAX_CLIENTS);   public void run()
   { 
      int i = 1;
      Socket clientSocket=null;
      try
      { 
         listenSocket=new ServerSocket(SERVER_PORT,MAX_CLIENTS);
         while (true)
         { try
            { 
               sleep(5);
            }
            catch(InterruptedException e)
            { System.err.println("Sleep InterruptedException : "+e);
            }
            // Accept a new client.
            clientSocket = listenSocket.accept();
            clientSocketVect.add(clientSocket);
            new ThreadedEchoHandler(clientSocket, i).start();
            System.out.println("Spawning " + i);
            
            i++;
         }
      }
      catch(IOException excpt)
      { System.err.println("Unable to listen on port "+SERVER_PORT+" : "+excpt);
         //shutoff();
         //return;
      }
   }   protected void status(boolean Status)
   {
      keepRunning = Status;
   }
   public void shutoff()
   { try
      { //System.out.println("Socket Closed _shutoff.");
         listenSocket.close();
         for (Enumeration e=clientSocketVect.elements() ; e.hasMoreElements() ;) {
            ((Socket) e.nextElement()).close();
         }
         
      }
      catch(IOException excpt)
      {
         System.err.println("Failed I/O: "+ excpt);
      }
   }
}