当前位置：首页 > news >正文

【从零学javase 第六天】网络编程（+多线程）

news 2026/3/26 21:26:30

Java 网络编程实战教程：从零基础到群聊

本文适合刚会 Java 的同学，带你从零基础学 Java 网络编程，最终实现多客户端群聊。

一、网络编程基础概念

网络编程就是用程序让两台电脑互相传递信息。

IP 地址：电脑的网络位置，例如127.0.0.1（本机）
端口号：程序监听的“门牌号”，例如8888
客户端（Client）：发送消息
服务器（Server）：接收消息

TCP（可靠通信）与 UDP（快速通信）：

TCP：保证顺序、保证不丢包，适合聊天、文件传输
UDP：不保证顺序、可能丢包，适合视频、语音、游戏

本文先用 TCP 实现基础聊天程序，然后扩展到多客户端和群聊。

二、单客户端聊天（客户端 + 服务器）

服务器端（Server.java）

importjava.io.*;importjava.net.*;publicclassServer{publicstaticvoidmain(String[]args)throwsException{ServerSocketserver=newServerSocket(8888);System.out.println("服务器启动，等待客户端连接...");Socketsocket=server.accept();System.out.println("客户端已连接");BufferedReaderreader=newBufferedReader(newInputStreamReader(socket.getInputStream()));PrintWriterwriter=newPrintWriter(socket.getOutputStream(),true);Stringmsg;while((msg=reader.readLine())!=null){System.out.println("客户端说："+msg);writer.println("收到："+msg);if(msg.equalsIgnoreCase("bye"))break;}socket.close();server.close();}}

客户端（Client.java)

importjava.io.*;importjava.net.*;publicclassClient{publicstaticvoidmain(String[]args)throwsException{Socketsocket=newSocket("127.0.0.1",8888);System.out.println("已连接服务器");BufferedReaderconsole=newBufferedReader(newInputStreamReader(System.in));BufferedReaderreader=newBufferedReader(newInputStreamReader(socket.getInputStream()));PrintWriterwriter=newPrintWriter(socket.getOutputStream(),true);Stringmsg;while(true){System.out.print("发送给服务器：");msg=console.readLine();writer.println(msg);if(msg.equalsIgnoreCase("bye"))break;Stringreply=reader.readLine();System.out.println("服务器说："+reply);}socket.close();}}

三、多线程服务器（同时服务多个客户端）

importjava.io.*;importjava.net.*;publicclassMultiServer{publicstaticvoidmain(String[]args)throwsException{ServerSocketserver=newServerSocket(8888);System.out.println("多线程服务器启动...");while(true){Socketsocket=server.accept();newThread(()->handleClient(socket)).start();}}privatestaticvoidhandleClient(Socketsocket){try{BufferedReaderreader=newBufferedReader(newInputStreamReader(socket.getInputStream()));PrintWriterwriter=newPrintWriter(socket.getOutputStream(),true);Stringmsg;while((msg=reader.readLine())!=null){System.out.println("客户端说："+msg);writer.println("收到："+msg);if(msg.equalsIgnoreCase("bye"))break;}socket.close();}catch(IOExceptione){e.printStackTrace();}}}

四、群聊功能实现

importjava.io.*;importjava.net.*;importjava.util.*;publicclassChatServer{privatestaticList<PrintWriter>clients=newArrayList<>();publicstaticvoidmain(String[]args)throwsException{ServerSocketserver=newServerSocket(8888);System.out.println("群聊服务器启动...");while(true){Socketsocket=server.accept();newThread(()->handleClient(socket)).start();}}privatestaticvoidhandleClient(Socketsocket){try{BufferedReaderreader=newBufferedReader(newInputStreamReader(socket.getInputStream()));PrintWriterwriter=newPrintWriter(socket.getOutputStream(),true);synchronized(clients){clients.add(writer);}Stringmsg;while((msg=reader.readLine())!=null){System.out.println("收到："+msg);broadcast(msg);if(msg.equalsIgnoreCase("bye"))break;}synchronized(clients){clients.remove(writer);}socket.close();}catch(IOExceptione){e.printStackTrace();}}privatestaticvoidbroadcast(Stringmsg){synchronized(clients){for(PrintWriterout:clients){out.println(msg);}}}}