Java Socket通信

import java.io.BufferedReader;  
import java.io.IOException;  
import java.io.InputStreamReader;  
import java.io.PrintStream;  
import java.net.Socket;  
import java.net.SocketTimeoutException;  

public class Client {  
    public static void main(String[] args) throws IOException {  
        //客户端请求与本机在20006端口建立TCP连接   
        Socket client = new Socket("127.0.0.1", 20006);  
        client.setSoTimeout(10000);  
        //获取键盘输入   
        BufferedReader input = new BufferedReader(new InputStreamReader(System.in));  
        //获取Socket的输出流，用来发送数据到服务端    
        PrintStream out = new PrintStream(client.getOutputStream());  
        //获取Socket的输入流，用来接收从服务端发送过来的数据    
        BufferedReader buf =  new BufferedReader(new InputStreamReader(client.getInputStream()));  
        boolean flag = true;  
        while(flag){  
            System.out.print("输入信息：");  
            String str = input.readLine();  
            //发送数据到服务端    
            out.println(str);  
            if("bye".equals(str)){  
                flag = false;  
            }else{  
                try{  
                    //从服务器端接收数据有个时间限制（系统自设，也可以自己设置），超过了这个时间，便会抛出该异常  
                    String echo = buf.readLine();  
                    System.out.println(echo);  
                }catch(SocketTimeoutException e){  
                    System.out.println("Time out, No response");  
                }  
            }  
        }  
        input.close();  
        if(client != null){  
            //如果构造函数建立起了连接，则关闭套接字，如果没有建立起连接，自然不用关闭  
            client.close(); //只关闭socket，其关联的输入输出流也会被关闭  
        }  
    }  
}  

import java.io.BufferedReader;  
import java.io.InputStreamReader;  
import java.io.PrintStream;  
import java.net.Socket;  
import java.net.ServerSocket;  



/** 
 * 该类为多线程类，用于服务端 
 */  
class ServerThread implements Runnable {  

    private Socket client = null;  
    public ServerThread(Socket client){  
        this.client = client;  
    }  

    @Override  
    public void run() {  
        try{  
            //获取Socket的输出流，用来向客户端发送数据  
            PrintStream out = new PrintStream(client.getOutputStream());  
            //获取Socket的输入流，用来接收从客户端发送过来的数据  
            BufferedReader buf = new BufferedReader(new InputStreamReader(client.getInputStream()));  
            boolean flag =true;  
            while(flag){  
                //接收从客户端发送过来的数据  
                String str =  buf.readLine();  
                if(str == null || "".equals(str)){  
                    flag = false;  
                }else{  
                    if("bye".equals(str)){  
                        flag = false;  
                    }else{  
                        //将接收到的字符串前面加上echo，发送到对应的客户端  
                        out.println("echo:" + str);  
                    }  
                }  
            }  
            out.close();  
            client.close();  
        }catch(Exception e){  
            e.printStackTrace();  
        }  
    }  

}  

public class Server {  
    public static void main(String[] args) throws Exception{  
        //服务端在20006端口监听客户端请求的TCP连接  
        ServerSocket server = new ServerSocket(20006);  
        Socket client = null;  
        boolean f = true;  
        while(f){  
            //等待客户端的连接，如果没有获取连接  
            client = server.accept();  
            System.out.println("与客户端连接成功！");  
            //为每个客户端连接开启一个线程  
            new Thread(new ServerThread(client)).start();  
        }  
        server.close();  
    }  
}