Java套接字

前言：　

　　本文补充一下Java关于套接字方面的内容，因为其应用相对比较简单，所以下面介绍两个程序实例。

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1.Socket对接过程

(注：这是之前在网上见过一张图片，大致过程还是比较清晰的）

分析：

• Socket对接之后的数据传送类似于文件的读写；
• 流套接字采用TCP传输数据流，一旦数据发送失败将重传，所以具有安全无损的特点。

2.实例一【Server->Client(1:1)】

 package socket;

 import java.io.DataInputStream;
 import java.io.DataOutputStream;
 import java.io.IOException;
 import java.net.Inet4Address;
 import java.net.InetAddress;
 import java.net.ServerSocket;
 import java.net.Socket;
 import java.util.Date;

 public class Server {

     public Server(){
         try {
             //服务端开启端口8000
             ServerSocket serverSocket = new ServerSocket(8000);
             System.out.println("server start at:"+new Date());
             //等待客户端相应
             Socket socket  = serverSocket.accept();
             InetAddress address = socket.getInetAddress();
             System.out.println("connected with address:"+address.getHostAddress());
             DataInputStream input = new DataInputStream(socket.getInputStream());
             DataOutputStream output = new DataOutputStream(socket.getOutputStream());

             //while(true){
             int num = input.readInt();
             System.out.println(num);
             //}

         } catch (IOException e) {
             e.printStackTrace();
         }
     }

     public static void main(String[] args) {
         new Server();
     }

 }

 package socket;

 import java.io.DataInputStream;
 import java.io.DataOutputStream;
 import java.net.Socket;

 public class Client {
     public static void main(String[] args) throws Exception {

         System.out.println("--client--");

         //Socket(,)内参数分别设为服务端IP和端口
         Socket socket = new Socket("localhost", 8000);

         DataInputStream input = new DataInputStream(socket.getInputStream());
         DataOutputStream output = new DataOutputStream(socket.getOutputStream());

         int x = 222;
         output.writeInt(x);
         System.out.println("data convented:"+x);
     }
 }

服务端输出（执行之后显示红点，表示等待中...）：

server start at:Sat Aug 15 19:39:40 CST 2015
connected with address:127.0.0.1
222

客户端输出：

--client--
data convented:222

3.实例二【Server->Client(1:n)】

 package socket;

 import java.io.DataInputStream;
 import java.io.DataOutputStream;
 import java.net.InetAddress;
 import java.net.ServerSocket;
 import java.net.Socket;
 import java.util.Date;

 public class SuperServer {
     private int countOfClient=0;
     public SuperServer() {
         try {
             ServerSocket serverSocket = new ServerSocket(8000);
             System.out.println("server start at:" + new Date());

             while (true) {
                 Socket socket = serverSocket.accept();
                 InetAddress address = socket.getInetAddress();
                 System.out.println("connected with address:"
                         + address.getHostAddress());
                 //为每一位Client创建一个单独的线程
                 new Thread(new ConnectTask(socket)).start();
                 countOfClient++;
                 System.out.println("this is the "+countOfClient + "(th) of client. ");
             }
         } catch (Exception e) {
             e.printStackTrace();
         }

     }

     public static void main(String[] args) {
         new SuperServer();
     }

     class ConnectTask implements Runnable {
         private Socket socket = null;

         public ConnectTask(Socket socket) {
             this.socket = socket;
         }

         @Override
         public void run() {
             try {
                 DataInputStream input = new DataInputStream(
                         socket.getInputStream());
                 DataOutputStream output = new DataOutputStream(
                         socket.getOutputStream());

                 int numFromClient = input.readInt();
                 System.out.println("number from client:"+numFromClient);
             } catch (Exception e) {
                 e.printStackTrace();
             }
         }

     }

 }

　　以上代码中，服务端创建多线程，给每一个对接的客户端分一个独立的线程；客户端代码不变，还是实例一的代码。程序输出跟实例一近似，只不过这是服务端一直运行着，可供多个客户端连接。（因为独立分配线程，程序运行时资源比较浪费，所以代码仅供参考，有待优化！）