Socket网络协议之一

客户端：Socket一般也称作”套接字“，用于描述IP地址和端口，废话很少说，它就是网络通讯过程当中端点的抽象表示。值得一提的是，Java在包java.net中提供了两个类Socket和ServerSocket，分别用来表示双向链接的客户端和服务端。这是两个封装得很是好的类，使用起来很方便！

    下面将首先建立一个SocketServer的类做为服务端以下，该服务端实现了多线程机制，能够在特定端口处监听多个客户请求，一旦有客户请求，Server老是会建立一个服务纯种来服务新来的客户，而本身继续监听。程序中accept()是一个阻塞函数，所谓阻塞性方法就是说该方法被调用后将等待客户的请求，直到有一个客户启动并请求链接到相同的端口，而后accept()返回一个对应于客户的Socket。这时，客户方和服务方都创建了用于通讯的Socket，接下来就是由各个Socket分别打开各自的输入、输出流。

• SocketServer类，服务器实现：

package server;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.ServerSocket;
import java.net.Socket;
public class SocketServer {
 ServerSocket sever;   
 
 public  SocketServer(int port){
        try{
            sever = new ServerSocket(port);
        }catch(IOException e){
            e.printStackTrace();
        }
    }
    
    public void beginListen(){
        while(true){
            try{
                final Socket socket = sever.accept();
                
                new Thread(new Runnable(){
                    public void run(){
                        BufferedReader in;
                        try{
                            in = new BufferedReader(new InputStreamReader(socket.getInputStream(),"UTF-8"));
                            PrintWriter out = new PrintWriter(socket.getOutputStream());
                            while (!socket.isClosed()){
                                String str;
                                str = in.readLine();
                                out.println("Hello!world!! " + str);
                                out.flush();
                                if (str == null || str.equals("end"))
                                    break;
                                System.out.println(str);
                            }
                            socket.close();
                        }catch(IOException e){
                            e.printStackTrace();
                        }
                    }
                }).start();
            }catch(IOException e){
                e.printStackTrace();
            }
        }
    }
    
}

• SocketClient类，客户端实现：

package client;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.Socket;
import java.net.UnknownHostException;
public class SocketClient {
  static Socket client;
     
    public  SocketClient(String site, int port){
        try{
            client = new Socket(site,port);
            System.out.println("Client is created! site:"+site+" port:"+port);
        }catch (UnknownHostException e){
            e.printStackTrace();
        }catch (IOException e){
            e.printStackTrace();
        }
    }
    
    public String sendMsg(String msg){
        try{
            BufferedReader in = new BufferedReader(new InputStreamReader(client.getInputStream()));
            PrintWriter out = new PrintWriter(client.getOutputStream());
            out.println(msg);
            out.flush();
            return in.readLine();
        }catch(IOException e){
            e.printStackTrace();
        }
        return "";
    }
    public void closeSocket(){
        try{
            client.close();
        }catch(IOException e){
            e.printStackTrace();
        }
    }
    public static void main(String[] args) throws Exception{
        
    }
}

接下来就是来测试Socket通讯了！

 先运行TestServer类，打开服务端，在12345端口处监听！

package server;
public class TestServer {
 /**
  * @param args
  */
 public static void main(String[] argvs){
           SocketServer server = new SocketServer(1234);
           server.beginListen();
      }
}

 再运行TestClient类： 

package client;
public class TestClient {
 /**
  * @param args
  */
 public static void main(String[] args) {
  // TODO Auto-generated method stub
        SocketClient client = new SocketClient("127.0.0.1",1234);
        System.out.println(client.sendMsg("nimei1"));
        client.closeSocket();
        
        SocketClient client1 = new SocketClient("127.0.0.1",1234);
        System.out.println(client1.sendMsg("nimei1111"));
        client1.closeSocket();
        
        SocketClient client11 = new SocketClient("127.0.0.1",1234);
        System.out.println(client11.sendMsg("nimei11111111"));
        client11.closeSocket();
        
        SocketClient client111 = new SocketClient("127.0.0.1",1234);
        System.out.println(client111.sendMsg("nimei11111111111111111"));
        client111.closeSocket();
        
 }
}

输出结果以下：

服务端：

nimei1
nimei1111
nimei11111111
nimei11111111111111111

 

客户端：

Client is created! site:127.0.0.1 port:1234
Hello!world!! nimei1
Client is created! site:127.0.0.1 port:1234
Hello!world!! nimei1111
Client is created! site:127.0.0.1 port:1234
Hello!world!! nimei11111111
Client is created! site:127.0.0.1 port:1234
Hello!world!! nimei11111111111111111