java socket 实现服务端与客户端

一对一的服务端和客户机：一个服务端只能同时服务一个客户端
服务端：

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

public class MyServer {
 public static void main(String[] args) throws IOException{
  ServerSocket server=new ServerSocket(5678);
  Socket client=server.accept();
        BufferedReader in=new BufferedReader(new InputStreamReader(client.getInputStream()));
        PrintWriter out=new PrintWriter(client.getOutputStream());
        while(true){
                 String str=in.readLine();
                System.out.println(str);
                out.println("has receive....");
                 out.flush();
                 if(str.equals("end"))
                         break;
                }
                client.close();
        }
}

accept()方法说明：
public Socket accept() throws IOException
Listens for a connection to be made to this socket and accepts it. The method blocks until a connection is made.
A new Socket s is created and, if there is a security manager, the security manager‘s checkAccept method is called with s.getInetAddress().getHostAddress() and s.getPort() as its arguments to ensure the operation is allowed. This could result in a SecurityException.

客户端
import java.net.*;
import java.io.*;

public class Client{
 static Socket server;
 
 public static void main(String[] args)throws Exception{
  server=new Socket(InetAddress.getLocalHost(),5678);
         BufferedReader in=new BufferedReader(new InputStreamReader(server.getInputStream()));
         PrintWriter out=new PrintWriter(server.getOutputStream());
         //标准输入
  BufferedReader wt=new BufferedReader(new InputStreamReader(System.in));
 
  while(true){
           String str=wt.readLine();
           out.println(str);
           out.flush();
           if(str.equals("end")){
                    break;
          }
           System.out.println(in.readLine());
  }
  server.close();
 }
}

一对多的服务端和客户机：一个服务端只能同时服务多个客户端，需要使用多线程来实现

服务端：调用具体的处理线程完成处理
import java.io.*;
import java.net.*;

public class MyMultiServer {
 public static void main(String[] args) throws IOException{
  ServerSocket server=new ServerSocket(5678);
  while (true){
                Socket client=server.accept();
                ChildTh child=new ChildTh(client);//用socket实例初始化具体的处理线程对象
                //使用Runnable接口和使用extends Thread的区别：
                // 如果是使用Runnable接口，需要这么写：
                   new Thread(child).start();               
                //注意：不能写成：child.run();
                // 如果使用extends Thread，只需要child.start()就可以，因为start()是Thread的方法
                }
        }
}       

处理线程类：
import java.io.*;
import java.net.*;
public class ChildTh implements Runnable{
        private Socket client;
        public ChildTh(Socket client){
                this.client=client;
        }
       
        public void run(){       
           try{       
             BufferedReader in=new BufferedReader(new InputStreamReader(client.getInputStream()));
             PrintWriter out=new PrintWriter(client.getOutputStream());
             while(true){
                     String str=in.readLine();
                     System.out.println(str);
                     out.println("has receive....");
                     out.flush();
                     if(str.equals("end"))
                        break;
             }       
                       
             client.close();
            }catch(Exception e){
                  System.out.println("error in the close the socket!");                       
                  e.printStackTrace();
              }
              finally{
                                                               
              }
        }
       
}

客户端：
import java.net.*;
import java.io.*;

public class Client{
 static Socket server;
 
 public static void main(String[] args)throws Exception{
  server=new Socket(InetAddress.getLocalHost(),5678);
         BufferedReader in=new BufferedReader(new InputStreamReader(server.getInputStream()));
         PrintWriter out=new PrintWriter(server.getOutputStream());
         //标准输入
  BufferedReader wt=new BufferedReader(new InputStreamReader(System.in));
 
  while(true){
           String str=wt.readLine();
           out.println(str);
           out.flush();
           if(str.equals("end")){
                    break;
          }
           System.out.println(in.readLine());
  }
  server.close();
 }
}