廖雪峰Java13网络编程-1Socket编程-3TCP多线程编程

Posted 2022-03-23 csj2018

TCP多线程编程
一个ServerSocket可以和多个客户端同时建立连接，所以一个Server可以同时与多个客户端建立好的Socket进行双向通信。
因此服务器端，当我们打开一个Socket以后，通常使用一个无限for循环，在这个for循环内部，每次调用accept方法，返回一个与远程客户新建的Socket连接，紧接着启动一个新的线程，来处理这个连接。

    ServerSocket ss = new ServerSocket(port);
    for( ; ; )
        Socket sock = ss.accept();
        Thread t = new Thread()
            public void run()
                process(sock);
            
        
        t.start();
    

TCPServer.java

import java.io.*;
import java.net.ServerSocket;
import java.net.Socket;
import java.nio.charset.StandardCharsets;
import java.time.LocalDateTime;

public class TCPServer 
    public static void main(String[] args) throws Exception
        ServerSocket ss = new ServerSocket(9090);
        System.out.println("TCP Server ready");
        for(;;)
            Socket sock = ss.accept();
            System.out.println("Accept from "+sock.getRemoteSocketAddress());
            TimeHandle handle = new TimeHandle(sock);
            handle.start();
        
    

class TimeHandle extends Thread
    Socket sock;
    TimeHandle(Socket sock)
        this.sock = sock;
    
    public void run()
        try(BufferedReader reader = new BufferedReader(new InputStreamReader(sock.getInputStream(), StandardCharsets.UTF_8)))
            try(BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(sock.getOutputStream(),StandardCharsets.UTF_8)))
                for(;;)
                    String cmd = reader.readLine();
                    if("q".equals(cmd))
                        writer.write("bye!\\n");
                        writer.flush();
                        break;
                    else if("time".equals(cmd))
                        writer.write(LocalDateTime.now().toString()+"\\n");
                        writer.flush();
                    else
                        writer.write("Sorry?\\n");
                        writer.flush();
                    
                
            
        catch (IOException e)
            e.printStackTrace();
        finally 
            try
                this.sock.close();
            catch (IOException e)
                e.printStackTrace();
            
        
    

运行2次client，服务器端的运行结果

TCPClient.java

import java.io.*;
import java.net.InetAddress;
import java.net.Socket;
import java.nio.charset.StandardCharsets;

public class TCPClient 
    public static void main(String[] args) throws Exception
        InetAddress addr = InetAddress.getByName("localhost");
        System.out.println(addr);
        try(Socket sock = new Socket(addr,9090))
            try(BufferedReader reader = new BufferedReader(new InputStreamReader(sock.getInputStream(), StandardCharsets.UTF_8)))
                try(BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(sock.getOutputStream(),StandardCharsets.UTF_8)))
                    writer.write("time\\n");
                    writer.flush();
                    String resp = reader.readLine();
                    System.out.println("Response:"+resp);
                    Thread.sleep(1000);
                    writer.write("q\\n");
                    writer.flush();
                    resp=reader.readLine();
                    System.out.println("Response:"+resp);
                
            
        
    

总结：

TCP多线程编程模型：

• 服务器端使用无限循环
• 每次accept返回后，创建新的线程来处理客户端请求
• 每个客户端请求对应一个服务线程
• 使用线程池可以提高运行效率