Socket通常也称做”套接字“，用于描述IP地址和端口，废话不多说，它就是网络通信过程中端点的抽象表示。值得一提的是，Java在包java.net中提供了两个类Socket和ServerSocket，分别用来表示双向连接的客户端和服务端。这是两个封装得非常好的类，使用起来很方便！
下面将首先创建一个SocketServer的类作为服务端如下，该服务端实现了多线程机制，可以在特定端口处监听多个客户请求，一旦有客户请求，Server总是会创建一个服务纯种来服务新来的客户，而自己继续监听。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连接到相同的端口，然后accept()返回一个对应于客户的Socket。这时，客户方和服务方都建立了用于通信的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：
1 package HA.Socket; 2 3 import java.io. * ; 4 import java.net. * ; 5 6 public class SocketServer { 7 8 ServerSocket sever; 9 10 public SocketServer( int port){ 11 try { 12 sever = new ServerSocket(port); 13 } catch (IOException e){ 14 e.printStackTrace(); 15 } 16 } 17 18 public void beginListen(){ 19 while ( true ){ 20 try { 21 final Socket socket = sever.accept(); 22 23 new Thread( new Runnable(){ 24 public void run(){ 25 BufferedReader in ; 26 try { 27 in = new BufferedReader( new InputStreamReader(socket.getInputStream(), " UTF-8 " )); 28 PrintWriter out = new PrintWriter(socket.getOutputStream()); 29 while ( ! socket.isClosed()){ 30 String str; 31 str = in .readLine(); 32 out .println( " Hello!world!! " + str); 33 out .flush(); 34 if (str == null || str.equals( " end " )) 35 break ; 36 System. out .println(str); 37 } 38 socket.close(); 39 } catch (IOException e){ 40 e.printStackTrace(); 41 } 42 } 43 }).start(); 44 } catch (IOException e){ 45 e.printStackTrace(); 46 } 47 } 48 } 49 }
- SocketClient类，客户端实现：
1 package HA.Socket; 2 3 import java.io. * ; 4 import java.net. * ; 5 6 public class SocketClient { 7 static Socket client; 8 9 public SocketClient(String site, int port){ 10 try { 11 client = new Socket(site,port); 12 System. out .println( " Client is created! site: " + site + " port: " + port); 13 } catch (UnknownHostException e){ 14 e.printStackTrace(); 15 } catch (IOException e){ 16 e.printStackTrace(); 17 } 18 } 19 20 public String sendMsg(String msg){ 21 try { 22 BufferedReader in = new BufferedReader( new InputStreamReader(client.getInputStream())); 23 PrintWriter out = new PrintWriter(client.getOutputStream()); 24 out .println(msg); 25 out .flush(); 26 return in .readLine(); 27 } catch (IOException e){ 28 e.printStackTrace(); 29 } 30 return "" ; 31 } 32 public void closeSocket(){ 33 try { 34 client.close(); 35 } catch (IOException e){ 36 e.printStackTrace(); 37 } 38 } 39 public static void main(String[] args) throws Exception{ 40 41 } 42 43 }
接下来就是来测试Socket通信了！
先运行TestSocketServer类，打开服务端，在12345端口处监听！
1 package HA.Socket; 2 3 public class TestSocketServer { 4 5 public static void main(String[] argvs){ 6 SocketServer server = new SocketServer( 12345 ); 7 server.beginListen(); 8 } 9 }
再运行TestSocketClient类：
1 package HA.Socket; 2 3 public class TestSocketClient { 4 5 public static void main(String[] args){ 6 7 SocketClient client = new SocketClient( " 127.0.0.1 " , 12345 ); 8 System. out .println(client.sendMsg( " nimei1 " )); 9 client.closeSocket(); 10 11 SocketClient client1 = new SocketClient( " 127.0.0.1 " , 12345 ); 12 System. out .println(client1.sendMsg( " nimei1111 " )); 13 client1.closeSocket(); 14 15 SocketClient client11 = new SocketClient( " 127.0.0.1 " , 12345 ); 16 System. out .println(client11.sendMsg( " nimei11111111 " )); 17 client11.closeSocket(); 18 19 SocketClient client111 = new SocketClient( " 127.0.0.1 " , 12345 ); 20 System. out .println(client111.sendMsg( " nimei11111111111111111 " )); 21 client111.closeSocket(); 22 23 } 24 }
输出结果如下：
服务端：
Client is created ! site: 127.0 . 0.1 port: 12345 Hello ! world !! nimei1Client is created ! site: 127.0 . 0.1 port: 12345 Hello ! world !! nimei1111Client is created ! site: 127.0 . 0.1 port: 12345 Hello ! world !! nimei11111111Client is created ! site: 127.0 . 0.1 port: 12345 Hello ! world !! nimei11111111111111111
客户端：
nimei1nimei1111nimei11111111nimei11111111111111111