JAVA实现端到端的通信

[shenghaishiweini]

例如A,B两个客户端（A是高级客户端，可以通过网络控制B），A要发"MY NAME IS..."给B，怎么发？我想到的是通过服务器转发，用SOCKET，可是，A给服务器发了，服务器要怎么才能发给B啊（B的IP地址知道）？如果不通过服务器，那还有什么办法？上网也看了一些，说的都有些晕乎， 哪位高手能帮下忙啊。。。

[打油的程序员]

A要发"MY NAME IS..."给B， B接收信息.做出响应，A，B都要运行某种软件

这跟点对点聊天程序不是类似吗？A发送信息给B，B接收信息，提取有效信息，并显示出来或者执行其他操作

可以采取TCP方式或UDP方式

当然了，通过第三方（服务器）转发也是可以的，这时又类似多人聊天室，服务器接收请求之后，向过滤后的IP发送信息，

UDP方式的点对点聊天示例：

import java.awt.*;
import java.awt.event.*;
import java.io.*;
import java.net.*;
import java.util.*;
import javax.swing.*;
import java.util.regex.*;;

public class PointToPointUDPChat {
    Frame f = new Frame("点对点聊天");

    Label lbRemoteIP = new Label("目标IP");// 对方IP
    Label lbRemotePort = new Label("目标端口");
    Label lbLocalSendPort = new Label("本地发送端口");
    Label lbLocalReceivePort = new Label("本地接收端口");

    TextField tfRemoteIP = new TextField(15);// 要发送数据的目标IP
    TextField tfRemotePort = new TextField(15);// 要发送数据的目标端口
    TextField tfLocalSendPort = new TextField(15);// 使用此端口发送数据
    TextField tfLocalReceivePort = new TextField(15);// 使用此端口发送数据

    String remoteIP = null;
    int remotePort = 0;
    int localSendPort = 0;
    int localReceivePort = 0;
    
    TextArea allChatContent = new TextArea();
    TextField sendChatContent = new TextField(20);

    Button connect = new Button("连接");
    Button disConnect = new Button("断开");
    Button bt = new Button("发送");
    Thread receiveThread = null;// 利用start和stop控制是否接收消息

    public PointToPointUDPChat() {
	initFrame();
    }

    public static void main(String args[]) {
	new PointToPointUDPChat();
    }

    // 外观布局，添加事件响应
    public void initFrame() {// //////

	f.setSize(400, 500);// 设置容器的大小
	f.setLayout(new BorderLayout());
	Panel p = new Panel();
	Panel p2 = new Panel();

	// 添加组件，布置布局
	p.setLayout(new GridLayout(5, 5));
	p.add(lbRemoteIP);
	p.add(tfRemoteIP);
	p.add(lbRemotePort);
	p.add(tfRemotePort);
	p.add(lbLocalSendPort);
	p.add(tfLocalSendPort);
	p.add(lbLocalReceivePort);
	p.add(tfLocalReceivePort);
	p.add(connect);
	p.add(disConnect);

	f.add("North", p);
	connect.addActionListener(new ActionListener() {// 连接按钮事件
		    public void actionPerformed(ActionEvent e) {
			try {
			    remoteIP = tfRemoteIP.getText();
			    remotePort = Integer.parseInt(tfRemotePort
				    .getText());
			    localSendPort = Integer.parseInt(tfLocalSendPort
				    .getText());
			    localReceivePort = Integer
				    .parseInt(tfLocalReceivePort.getText());
			} catch (Exception exception) {
			    prompt("连接信息不能为空或格式错误");
			    return;
			}
			if (!checkIP(remoteIP)) {
			    prompt("目标IP设置错误");
			    return;
			}
			if (!checkPort(remotePort)) {
			    prompt("目标端口设置错误");
			    return;
			}
			if (!checkPort(localSendPort)) {
			    prompt("本地发送端口设置错误");
			    return;
			}
			if (!checkPort(localReceivePort)) {
			    prompt("本地接收端口设置错误");
			    return;
			}
			prompt("连接成功");
			tfRemoteIP.setEditable(false);
			tfRemotePort.setEditable(false);
			tfLocalReceivePort.setEditable(false);
			tfLocalSendPort.setEditable(false);
			receiveMessage();
		    }
		});

	disConnect.addActionListener(new ActionListener() {// 断开按钮事件
		    public void actionPerformed(ActionEvent e) {
			tfRemoteIP.setEditable(true);
			tfRemotePort.setEditable(true);
			tfLocalReceivePort.setEditable(true);
			tfLocalSendPort.setEditable(true);
			tfLocalReceivePort.setText("");
			tfLocalSendPort.setText("");
			tfRemoteIP.setText("");
			tfRemotePort.setText("");

			remoteIP = null;
			remotePort = 0;
			localSendPort = 0;
			localReceivePort = 0;
			receiveThread.stop();
			prompt("断开成功");
		    }
		});

	f.add("Center", allChatContent);

	p2.setLayout(new FlowLayout());
	p2.add(bt);
	p2.add(sendChatContent);// ///p2面板添加发送按钮和要发送的内容
	f.add("South", p2);

	f.setVisible(true);// 让容器可显示
	f.setResizable(false);// 不可改变容器大小

	// 关闭窗口事件
	f.addWindowListener(new WindowAdapter() {
	    public void windowClosing(WindowEvent e) {
		f.setVisible(false);
		f.dispose();
		System.exit(0);
	    }
	});

	// //////触发发送按钮事件
	bt.addActionListener(new ActionListener() {
	    public void actionPerformed(ActionEvent e) {
		sendMessage();
	    }

	});
	// 模态显示按钮的触发事件

	// 输入文本框的触发事件
	sendChatContent.addActionListener(new ActionListener() {
	    public void actionPerformed(ActionEvent e) {
		sendMessage();
	    }
	});

    }

    // 发送数据
    public void sendMessage() {// 
	// 定义ds
	DatagramSocket ds = null;
	try {
	    ds = new DatagramSocket(localSendPort);
	} catch (SocketException e1) {
	    prompt("本地发送端口已被使用");
	    return;
	}
	// 设置发送信息
	String sendMessage = sendChatContent.getText().trim();
	if (sendMessage.equals("")) {
	    prompt("无效信息");
	    return;
	}
	byte[] buf = sendMessage.getBytes();// /////获得要发送的数据

	// 设置接收数据的远程IP地址
	InetAddress inetAddress = null;
	try {
	    inetAddress = InetAddress.getByName(tfRemoteIP.getText().trim());
	} catch (UnknownHostException e) {
	    prompt("非法远程IP地址");
	    return;
	}

	// 发送
	DatagramPacket dp = new DatagramPacket(buf, 0, buf.length, inetAddress,
		remotePort);
	try {
	    ds.send(dp);
	} catch (IOException e) {
	    prompt("网络故障，发送失败");
	    return;
	}
	sendChatContent.setText("");// //发送完数据，发送框重置为空

	allChatContent.append(new java.text.SimpleDateFormat(
		"yy-MM-dd HH:mm:ss").format(new Date())
		+ " send to Remote("
		+ dp.getAddress()
		+ " "
		+ dp.getPort()
		+ ") :\n");
	allChatContent.append(sendMessage + "\n");
	ds.close();
    }

    // 接收数据
    class MyRunnable implements Runnable {
	byte buf[] = new byte[1024];
	DatagramSocket ds = null;
	DatagramPacket dp = null;

	public void run() {
	    dp = new DatagramPacket(buf, 0, 1024);
	    try {
		ds = new DatagramSocket(localReceivePort);
	    } catch (SocketException e1) {
		prompt("本地接收端口已被使用");
		return;
	    }
	    while (true) {
		try {
		    ds.receive(dp);
		} catch (IOException e) {
		    ds.close();
		    e.printStackTrace();
		}
		String receiveMessage = new String(dp.getData(), 0, dp
			.getLength());
		allChatContent.append(new java.text.SimpleDateFormat(
			"yy-MM-dd HH:mm:ss").format(new Date())// 
			+ " from remote("
			+ dp.getAddress().getHostAddress()
			+ " " + dp.getPort() + ") :\n" + receiveMessage + "\n");
		sendChatContent.setCaretPosition(sendChatContent.getText()
			.length());

	    }
	}

    }

    public void receiveMessage() {//	
	receiveThread = new Thread(new MyRunnable());
	receiveThread.start();
    }

    // 异常处理
    public void prompt(String promptMessage) {
	JOptionPane.showConfirmDialog(null, promptMessage, "友情提示",
		JOptionPane.WARNING_MESSAGE);
    }

    public boolean checkPort(int port) {
	return String.valueOf(port).matches("\\d+") && port > 1024
		&& port <= 65535;

    }

    public boolean checkPort(String port) {
	return port.matches("\\d+") && Integer.parseInt(port) > 1024
		&& Integer.parseInt(port) <= 65535;

    }

    
    public static boolean isDigit(String text) {
	return text.matches("\\d+");
    }    
  

    public boolean checkIP(String ip) {	
	java.util.regex.Matcher m = Pattern.compile(
		"(\\d{1,3}).(\\d{1,3}).(\\d{1,3}).(\\d{1,3})").matcher(ip);
	if (m.find()) {
	    for (int i = 1; i <= 4; i++)
		if (Integer.parseInt(m.group(i)) < 0
			|| Integer.parseInt(m.group(i)) > 255)
		    return false;
	    return true;
	}
	return true;
    }

}