applet与servlet的网络通信

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Servlet Java 数据结构 Eclipse Tomcat

applet与servlet的网络通信的例子

新建web项目，项目结构如下图：

package client;

import java.applet.Applet;
import java.awt.Button;
import java.awt.HeadlessException;
import java.awt.Label;
import java.awt.TextArea;
import java.awt.TextField;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.ByteArrayOutputStream;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLConnection;

public class NetEcho extends Applet implements ActionListener {

	TextField txtOutput;
	Button btnOutput;
	TextArea txtInput;
	Label lblOutput;
	Label lblInput;
	int turnOutput = 0;

	public void actionPerformed(ActionEvent arg0) {
		// TODO Auto-generated method stub

		if (txtOutput.getText() == null || txtOutput.getText().equals("")) {
			return;
		}

		try {
			URL url = new URL(
					"http://localhost:8080/appletServlet/NetEchoServlet"); // 打开连接
			URLConnection con = url.openConnection();
			con.setUseCaches(false); // 不用浏览器缓存
			con.setDoOutput(true);
			con.setDoInput(true);
			// 设置请求消息头
			con.setRequestProperty("Content-type", "application/octet-stream");
			turnOutput += 1;
			ByteArrayOutputStream byteOut = new ByteArrayOutputStream();

			DataOutputStream out = new DataOutputStream(byteOut);
			out.writeInt(turnOutput);
			out.writeUTF(txtOutput.getText());
			out.flush();

			byte[] buff = byteOut.toByteArray();
			// 设置请求消息中数据长度
			con.setRequestProperty("Content-length", "" + buff.length);
			DataOutputStream buffout = new DataOutputStream(con
					.getOutputStream());
			buffout.write(buff); // 将缓冲区中数据发出
			buffout.flush();
			buffout.close();
			// 读取输入
			DataInputStream in = new DataInputStream(con.getInputStream());
			txtInput.append(in.readInt() + ":" + in.readUTF() + "\n");
			in.close();
		} catch (MalformedURLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}

	}

	public NetEcho() {
		super();
	}

	public void destroy() {
		// Put your code here
	}

	public String getAppletInfo() {
		return "This is my default applet created by Eclipse";
	}

	public void init() {
		// Put your code here
		lblOutput = new Label("发送的数据");
		lblInput = new Label("接收的数据");

		txtOutput = new TextField();
		txtOutput.setColumns(10);

		this.add(lblOutput);
		this.add(txtOutput);
		btnOutput = new Button("发送");
		this.add(btnOutput);
		txtInput = new TextArea("", 20, 30);
		this.add(lblInput);
		this.add(txtInput);
		btnOutput.addActionListener(this);

	}

	public void start() {
		// Put your code here
	}

	public void stop() {
		// Put your code here
	}

}

嵌入applet的html文件

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    <title>applet发送至servlet例子</title>
    
    <meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
    <meta http-equiv="description" content="this is my page">
    <meta http-equiv="content-type" content="text/html; charset=UTF-8">
    
    <!--<link rel="stylesheet" type="text/css" href="./styles.css">-->
    
  </head>
  
  <body>
    
    <applet codebase="." 
            code="client.NetEcho.class" 
            name="NetEcho" 
            width="320" 
            height="240">
      
        
    </applet>
  </body>
</html>

servlet的源码：

package server;

import java.io.ByteArrayOutputStream;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class NetEchoServlet extends HttpServlet {

	public void service(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
//设置响应头MIME类型
		response.setContentType("application/octet-stream");
		
		DataInputStream in = new DataInputStream(request.getInputStream());
		ByteArrayOutputStream byteOut = new ByteArrayOutputStream();
		
		DataOutputStream out = new DataOutputStream(byteOut);
		
//		读
		int i = in.readInt();
		String j = in.readUTF();
		
		out.writeInt(i); //写回客户端
		out.writeUTF(j);
		out.flush();
		
		byte[] buff = byteOut.toByteArray();
		response.setContentLength(buff.length);
		
//		取得输出流
		ServletOutputStream httpOut = response.getOutputStream();
		httpOut.write(buff); //发送
		httpOut.close();
	}

}

配置文件：web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.4" 
	xmlns="http://java.sun.com/xml/ns/j2ee" 
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
	xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee 
	http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd">
  <servlet>
    <description>This is the description of my J2EE component</description>
    <display-name>This is the display name of my J2EE component</display-name>
    <servlet-name>NetEchoServlet</servlet-name>
    <servlet-class>server.NetEchoServlet</servlet-class>
  </servlet>

  <servlet-mapping>
    <servlet-name>NetEchoServlet</servlet-name>
    <url-pattern>/NetEchoServlet</url-pattern>
  </servlet-mapping>
  <welcome-file-list>
    <welcome-file>index.jsp</welcome-file>
  </welcome-file-list>
</web-app>

在tomcat中部署后的目录结构：