guiclient.java

一个很好的学生成绩管理系统

import java.io.*;
import java.net.*;
import java.applet.*;
import java.util.*;
import javax.swing.*;


public class GUIClient extends JApplet 
{
    public static final int port = 1111;
    public static final String host = "localhost";
    public static final int maxChars = 400;

    //消息到来的监听对象
    protected Listener listener = null;
    protected Talk talk = null;
    
    //客户端socket
    protected Socket s = null;

    public void start() 
    {
        System.err.println("start() called");

        try 
        {
            s = new Socket(host, port);
        }
        catch (IOException e) 
        {
            System.err.println("Couldn't make socket: "+  e);
            this.cleanUp();
            return;
        }
 
        
        //实例化监听对象
        listener = new Listener(s, displayText, this);
        
        //实例化发送对象
        talk = new Talk(s, sendText, this);

    }

    public void AppendText(String toBeAppended) 
    {
        System.out.println("appendText "+toBeAppended);
        JTextArea w = displayText;
        String text = w.getText();
        if(text.length() + toBeAppended.length() > maxChars) 
        {
            //找到最早的一行
            int upTo = text.indexOf("\n");
            System.out.println("content before "+upTo+" is delete");
            //消除一行
            w.replaceRange("", 0, upTo+1);
            
            //text = w.getText();
        }
        w.append("\n"+toBeAppended);
    }
    
    public void init() 
    {
    	initComponents();
    }
    private void initComponents() 
    {
        displayText = new javax.swing.JTextArea();
        sendText = new javax.swing.JTextField();
        jLabel1 = new javax.swing.JLabel();
        jList1 = new javax.swing.JList();
        
        getContentPane().setLayout(new org.netbeans.lib.awtextra.AbsoluteLayout());
        
        addMouseListener(new java.awt.event.MouseAdapter() 
        {
            public void mouseReleased(java.awt.event.MouseEvent evt) 
            {
                formMouseReleased(evt);
            }
        });
        
        getContentPane().add(displayText, new org.netbeans.lib.awtextra.AbsoluteConstraints(0, 0, 290, 240));
        displayText.setLineWrap(true);
        displayText.setText("you must login first!!!");
        
        sendText.setText("jTextField1");
        sendText.addActionListener(new java.awt.event.ActionListener() 
        {
            public void actionPerformed(java.awt.event.ActionEvent evt) 
            {
                jTextField1ActionPerformed(evt);
            }
        });
        
        getContentPane().add(sendText, new org.netbeans.lib.awtextra.AbsoluteConstraints(0, 270, 290, -1));
        
        jLabel1.setText("jLabel1");
        getContentPane().add(jLabel1, new org.netbeans.lib.awtextra.AbsoluteConstraints(0, 250, 290, -1));
        
        jList1.setBorder(new javax.swing.border.MatteBorder(null));
        jList1.setBackground(java.awt.Color.darkGray);
        jList1.setPreferredSize(new java.awt.Dimension(50, 80));
        getContentPane().add(jList1, new org.netbeans.lib.awtextra.AbsoluteConstraints(310, 0, 120, 290));
        
    }

    private void jTextField1ActionPerformed(java.awt.event.ActionEvent evt) 
    {
        if (talk != null) 
	{
            //调用talk线程的发送方法
            talk.sendLine();
        }
    }

    private void formMouseReleased(java.awt.event.MouseEvent evt) 
    {
        // 此处读者自己添加
    }


    // 聊天显示区
    private javax.swing.JTextArea displayText; 
    // 消息发送区
    private javax.swing.JTextField sendText;
    //发送对象，读者自己完成
    private javax.swing.JLabel jLabel1;
    //在线用户列表，读者自己完成
    private javax.swing.JList jList1;

    public void destroy() 
    {
        System.err.println("destroy() called");
    }

    public void finalize() throws Throwable 
    {
        System.err.println("finalize() called");
    }

    public void stop() 
    {
        System.err.println("stop() called");
        cleanUp();
        super.stop();
    }

    public void cleanUp() 
    {
        System.err.println("cleanUp() called");

        if (talk != null && talk.running) 
        {
            talk.stop();
        }
        talk = null;
        System.err.println("talk thread stopped and forgotten");

        if (listener != null && listener.running) 
        {
            System.err.println("about to stop listener...");
            listener.stop();
            System.err.println("listener stopped ok");
        }
        listener = null;
        System.err.println("listener thread stopped and forgotten");

        removeAll();
        System.err.println("windows deleted");

        try 
        {
            if (s != null) 
            {
                s.close();
                System.err.println("socket closed ok");
            }
        }
        catch (IOException e) 
        {
            System.err.println("Couldn't close socket: " + e);
        }
        s = null;
    }


}



class Talk extends Thread {
    protected PrintStream sout;
    protected JTextField w;
    protected boolean running = false;
    protected GUIClient applet;

    public Talk(Socket s, JTextField window, GUIClient applet) 
    {
        //后台打印信息
        System.err.println("Making a talk...");
        //初始化文本域
        w = window;
        //初始化applet
        this.applet = applet;
        
        try 
        {
            //得到输出流
            sout = new PrintStream(s.getOutputStream());
            System.err.println("Talk thread opened output stream to server");
        }
        catch (IOException e) 
        {
            System.err.println ("Talk thread can't open output stream to server");
            running = false;
            applet.cleanUp();
            return;
        }
        
        //启动线程
        this.start();
    }

    public void run() 
    {
        System.err.println("Talk thread running...");
        running = true;
    }

    protected void finalize() throws Throwable 
    {
        sout.close();
        sout = null;
        System.err.println("Talk thread closed its output stream.");
       	System.out.println("Talk thread stopped.");
    }


    //该方法在发送按钮被点击或用户回车时触发
    public void sendLine() 
    {
        String line = w.getText();
        w.setText("");

        if (line == null||line.equals("")) 
        {
        	return;
        }
        
        //此处请读者添加协议处理
         
	//提供一个断行符
        line = line.trim() + "\n";

        sout.print(line);
        sout.flush();

    }
}


class Listener extends Thread 
{
    protected DataInputStream sin;
    protected JTextArea w;
    //监听类是否运行标志
    protected boolean running = false;
    protected GUIClient applet;

    public Listener(Socket s, JTextArea window, GUIClient applet) 
    {
        //后台打印初始化信息
        System.out.println("Making a listener...");
        //初始化文本域
        w = window;
        //初始化容器
        this.applet = applet;
        try 
        {
            //得到输入流对象
            sin = new DataInputStream(s.getInputStream());
            System.out.println("Listener thread opened its input stream.");
        }
        catch (IOException e) 
        {
            System.err.println ("Listener thread can't open input stream: " + e);
            running = false;
            applet.cleanUp();
            return;
        }
        
        //初始化以后启动线程
        this.start();
    }

    public void run() 
    {
       
	//打印后台运行信息，设置运行标志
        System.out.println("Listener thread starting...");
        running = true;

        String line;
        while (true) 
        {
            try 
            {
                //得到收到的信息
                line = sin.readLine();
            }
            catch (IOException e) 
            {
                System.err.println("Listener: error in readLine: " + e);
                running = false;
                applet.cleanUp();
                return;
            }

            // 如果连接中断
            if (line == null) 
            {
                System.out.println("Listener find connection closed: closing");
                running = false;
                applet.cleanUp();
                return;
            }

            applet.AppendText(line);

        }
    }
}