Java - TCP网络编程

import java.io.*;
import java.net.*;

public class TCP_Server {
    
    public static void main(String[] args){
        
        int port=8888;
        
        try {
            ServerSocket sock=new ServerSocket(port);
            System.out.println("服务器启动，Port："+sock.getLocalPort());
            while(true){
                Socket client=sock.accept(); //***注意，accept()是个阻塞函数，返回client socket***
                System.out.println("监测到TCP连接来自："+client.getRemoteSocketAddress());
                new WorkThread(client).start(); //多线程
            }    
        } 
        catch (IOException e) {
            System.out.println("ERROR Found: "+e.getMessage());
        }
        //end try catch
    
        
    }
}


class WorkThread extends Thread{
    
    Socket sock;
    public WorkThread(Socket sock){
        this.sock=sock;
    }
    
    public void run(){
        try{
            //此处用BufferedReader实现
            BufferedReader in=new BufferedReader(new InputStreamReader(sock.getInputStream()));
            PrintWriter out=new PrintWriter(sock.getOutputStream(),true);
            
            String s=null;
            while((s=in.readLine())!=null){ //断开会返回null
                if(s.equals("end"))
                    break;
                System.out.println("收到："+s);
                out.println("Server："+s);
            }
            
            /*注意,readLine()是个阻塞函数，放在while((s=readLine())!=null)中会堵塞程序，等待用户的数据。
             *有两种方式中断循环
             *1.用户端断开TCP程序，in.readLine()会返回null
             *2.用户正常退出，用户端发送个[结束标记]给服务器，服务器根据标记，中断循环
             */
            System.out.println("监测到TCP连接来自："+sock.getRemoteSocketAddress()+"已断开。");
            
            in.close();
            out.close();
            sock.close();
        }
        catch(IOException e){
            System.out.println(e.getMessage());
        }
    }
    
    
}

import java.net.*;
import java.io.*;
import java.util.*;

public class TCP_Client {

    public static void main(String[] args) {
        
        Scanner in=new Scanner(System.in);
        
        try{
            
            int port=8888;
            String ip="127.0.0.1";
            
            Socket sock=new Socket(ip, port);
            
            //从socket中输出
            PrintWriter out=new PrintWriter(sock.getOutputStream(),true);
            //从socket中读取，此处用Scanner实现
            Scanner input=new Scanner(sock.getInputStream());
            
            while(true){
                System.out.print("请输入消息：");
                String s=in.nextLine();
                if(s.equals("end")){
                    out.println(s);
                    break;
                }
                
                out.println(s);
                System.out.println("发送："+s);
                s=input.nextLine();
                System.out.println("收到："+s);
            }
            
            in.close();
            input.close();
            out.close();
            sock.close();
        }
        catch (IOException e){
            System.out.println("ERROR Found: "+e.getMessage());
        }

    }

}