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！）