Java网络编程，Socket实现一对一全双工通信聊天功能 - 好文

本文使用socket的长连接，进行消息的发送和接受。

1、两端

client 端，server端

2、两线程

客户端、服务器端，各开两个线程，实现读写，可以全双工通信，异步发送，异步接受。

3、两注意

1）程序等待输入和一直处于等待消息发来，所以，用到死循环；同时，避免使用socket.close();

否则报异常：java.net.SocketException: socket closed

2）读消息，用到的是行读，nextLine()方法，所以，一定要在发送消息时，在消息末尾追加加上换行符，否则读不到。

代码：

1、消息发送服务类
package com.socket.newChat; import java.io.IOException; import
java.io.PrintWriter; import java.net.Socket; import java.util.Scanner; /** *
Created by Liuxd on 2018-09-15. */ public class SendMessageService implements
Runnable { private Socket socket; private String name; public
SendMessageService(Socket socket, String name) { this.socket = socket;
this.name = name; } public void run() { PrintWriter pWriter = null; Scanner
scanner = null; try { pWriter = new PrintWriter(socket.getOutputStream());
scanner = new Scanner(System.in); while (true) { String s = scanner.nextLine();
pWriter.write(name + s + "\n"); pWriter.flush(); } } catch (IOException e) {
e.printStackTrace(); } finally { scanner.close(); pWriter.close(); } } }
2、消息接受服务类
package com.socket.newChat; import java.io.IOException; import
java.net.Socket; import java.util.Scanner; /** * Created by Liuxd on
2018-09-15. */ public class ReceiveMessageService implements Runnable { private
Socket socket; public ReceiveMessageService(Socket socket) { this.socket =
socket; } @Override public void run() { Scanner scanner = null; try { scanner =
new Scanner(socket.getInputStream()); while (scanner.hasNext()) {
System.out.println(scanner.nextLine()); } } catch (IOException e) {
e.printStackTrace(); } finally { scanner.close(); } } }
3、服务端
package com.socket.newChat; /** * Created by Liuxd on 2018-09-15. */ import
java.io.IOException; import java.net.ServerSocket; import java.net.Socket;
public class TestServer { public static void main(String[] args) throws
IOException { ServerSocket serverSocket = new ServerSocket(8081); while (true)
{ Socket socket=serverSocket.accept(); new Thread(new
SendMessageService(socket,"服务器端：")).start(); new Thread(new
ReceiveMessageService(socket)).start(); System.out.println("请输入..."); } } }
4、客户端
package com.socket.newChat; /** * Created by Liuxd on 2018-09-15. */ import
java.io.IOException; import java.net.Socket; import
java.net.UnknownHostException; public class TestClient { public static void
main(String[] args) { try { Socket socket = new Socket("127.0.0.1", 8081); new
Thread(new SendMessageService(socket,"客户端：")).start(); new Thread(new
ReceiveMessageService(socket)).start(); System.out.println("请输入..."); } catch
(UnknownHostException e) { e.printStackTrace(); } catch (IOException e) {
e.printStackTrace(); } } }

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