一个applet---servlet通讯的例子---applet文件

import java.applet.Applet;
import java.awt.*;
import java.awt.event.*;
import java.net.*;
import java.io.*;

public class sendapplet extends Applet implements ActionListener
{
    Label sendlable;
    Label messageInfo;
    Button sendButton;
    TextField sendText;
    TextField messageText;
    URLConnection connect;
    String message;
    URL chatURL;
    public String getAppletInfo()
    {
        return "this is a applet--servlet";
    }
    
    public synchronized void init()
    {
        super.init();
        resize(500,300);
        sendlable=new Label("Please enter Massage");
        messageInfo=new Label("What you hava send:");
        sendText=new TextField(40);
        sendButton=new Button("Send");
        messageText=new TextField(40);
        messageText.setEditable(false);
        //
        
        
        
        
        //
        Panel mainp=new Panel();
        GridBagLayout gbl=new GridBagLayout();
        GridBagConstraints gbc=new GridBagConstraints();
        gbc.weightx=0;
        gbc.weighty=0;
        gbc.gridy=0;
        gbc.gridx=0;
        gbc.gridwidth=10;
        gbc.gridheight=1;
        gbc.anchor=GridBagConstraints.CENTER;
        gbc.fill=GridBagConstraints.NONE;
        mainp.setLayout(gbl);
        gbl.setConstraints(sendlable,gbc);
        mainp.add(sendlable);
        gbc.gridy=1;
        gbc.gridwidth=9;
        gbc.fill=GridBagConstraints.HORIZONTAL;
        gbl.setConstraints(sendText,gbc);
        mainp.add(sendText);
        gbc.gridx=9;
        gbc.gridwidth=1;
        gbc.fill=GridBagConstraints.NONE;
        gbl.setConstraints(sendButton,gbc);
        mainp.add(sendButton);
        gbc.gridx=0;
        gbc.gridy=2;
        gbc.gridwidth=10;
        gbl.setConstraints(messageInfo,gbc);
        mainp.add(messageInfo);
        gbc.gridy=3;
        gbc.weighty=100;
        gbc.gridheight=10;
        gbc.fill=GridBagConstraints.BOTH;
        gbl.setConstraints(messageText,gbc);
        mainp.add(messageText);
        sendButton.addActionListener(this);
        //构造的panel加入到applet中
        setLayout(new BorderLayout());
        add("Center",mainp);
        chatURL=getCodeBase();
    }
    public synchronized void start()
    {
    }
    public synchronized void stop()
    {
    }
    public synchronized void destroy()
    {
    }
    
    //
    private void Send()
    {
        message=sendText.getText();
        sendText.setText("");
        //showStatus("Message send!");
        p("Message send!");
        messageText.setText("message");
        String queryString="/servlet/Receive?message"+URLEncoder.encode(message);
        p("Attemping to send :"+message);
        try{
            connect=(new URL(chatURL,queryString)).openConnection();
            showStatus("Open Connection!");
            connect.setDefaultUseCaches(false);
            connect.setUseCaches(false);
            connect.setDoInput(true);
            connect.setDoOutput(false);
            connect.connect();
            p("Make connection to "+connect);
            showStatus("Open Sream!");
            DataInputStream in=new DataInputStream(connect.getInputStream());
            showStatus("reading");
            message=in.readLine();
            while(message!=null)
            {
                messageText.setText(message);
                message=in.readLine();
                
            }//end while
           
           
        
           
        }//end try
        catch(MalformedURLException e2)
        {
              System.err.println("Malformedurlexception:"+e2.toString());
              
        }//end catch
        catch(IOException e1)
        {
              System.err.println(e1.toString());
              
        }
        
    }//end Send
    
    public void actionPerformed(ActionEvent e)
    {
        if(e.getSource()==sendButton)
        {
            Send();
        
        }
    
    }
    
    private void p(String debug)
    {   
         messageText.setText(debug);
        //System.out.println("app-servlet:"+debug);
        
    }
        
}

原文转自：http://www.ltesting.net