Java&&Android Socket简单用法

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：

  package HA.Socket;
   
   import java.io.*;
   import java.net.*;
   
    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 HA.Socket;
   
   import java.io.*;
   import java.net.*;
   
    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通信了！

  先运行TestSocketServer类，打开服务端，在12345端口处监听！

  package HA.Socket;
   
    public class TestSocketServer {
       
       public static void main(String[] argvs){
           SocketServer server = new SocketServer(12345);
           server.beginListen();
       }
   }

   再运行TestSocketClient类：

  package HA.Socket;
   
    public class TestSocketClient {
   
       public static void main(String[] args){
           
           SocketClient client = new SocketClient("127.0.0.1",12345);
           System.out.println(client.sendMsg("nimei1"));
           client.closeSocket();
           
           SocketClient client1 = new SocketClient("127.0.0.1",12345);
           System.out.println(client1.sendMsg("nimei1111"));
           client1.closeSocket();
           
           SocketClient client11 = new SocketClient("127.0.0.1",12345);
           System.out.println(client11.sendMsg("nimei11111111"));
           client11.closeSocket();
           
           SocketClient client111 = new SocketClient("127.0.0.1",12345);
           System.out.println(client111.sendMsg("nimei11111111111111111"));
           client111.closeSocket();
           
       }
   }

  输出结果如下：

  服务端：

  Client is created! site:127.0.0.1 port:12345
  Hello!world!! nimei1
  Client is created! site:127.0.0.1 port:12345
  Hello!world!! nimei1111
  Client is created! site:127.0.0.1 port:12345
  Hello!world!! nimei11111111
  Client is created! site:127.0.0.1 port:12345
  Hello!world!! nimei11111111111111111

  客户端：

  nimei1
  nimei1111
  nimei11111111
  nimei11111111111111111

  最后不得不提一下，如果要是在Android模拟器中实验的话，本地IP用127.0.0.1是不行的，因为android模拟器内部的本地ip为10.0.2.2。要么就是用电脑的网络地址，模拟器和电脑相当于构成了一个局域网。