网络协议学习

TCP协议：Socket，可靠的服务：A-->B  三次握手

UDP协议：不可靠，短信功能

 

TCP：

package protocol;
import java.net.*;
import java.io.*;
public class TCPServer {
    public static void main(String[] args) throws Exception{
        //使用ServerSocket
        ServerSocket server=null;
        //每一个用户在程序中就是一个Socket
        Socket client=null;
     server=new ServerSocket(8888);
     //等待客户端连接
     client=server.accept();
     PrintWriter out=null;

     //准备向客户端打印信息
     out=new PrintWriter(client.getOutputStream());
     out.println("Hello");
     out.close(); //关闭流
     client.close();
     server.close();
    }
}

package protocol;
import java.io.*;
import java.net.*;
public class TCPClient {
    public static void main(String[] args)throws Exception {
        //表示一个客户端的Socket
        Socket client=null;
        //表示一个客户端的输入信息
        BufferedReader buf=null;
        client=new Socket("localhost",8888);
        buf=new BufferedReader(new InputStreamReader(client.getInputStream()));
        System.out.println(buf.readLine());
        buf.close();
        client.close();
    }
}

UDP:

package protocol;
import java.net.*;
import java.io.*;
public class UDPServer {
     public static void main(String[] args)throws Exception {

        DatagramSocket ds=null;
        DatagramPacket dp=null;
        //要保证UDP有一个运行的端口
        ds=new DatagramSocket(5000);
        String s="Hello MLDN haha";
        //建立服务器端的一个发送端
   dp=new DatagramPacket(s.getBytes(),0,s.length(),InetAddress.getByName("localhost"),9999);
        ds.send(dp);
        ds.close();
    }
}

package protocol;
import java.io.*;
import java.net.*;
public class UDPServerInput {
     public static void main(String[] args) throws Exception{
        DatagramSocket ds=null;
        DatagramPacket dp=null;
        //要保证UDP有一个运行的端口
        ds=new DatagramSocket(6000);
        //String s="Hello MLDN haha";
        //BufferedReader buf=new BufferedReader(new InputStreamReader(System.in));
        System.out.println("请输入要发送的信息:");
        //s=buf.readLine();
        byte b[]=new byte[1024];
     int len=System.in.read(b);
        //System.out.println(s.length());
        //dp=new DatagramPacket(s.getBytes(),0,s.length(),InetAddress.getByName("localhost"),9999);
        //dp.setData(s.getBytes());
     dp=new DatagramPacket(b,0,len,InetAddress.getByName("localhost"),9999);
        ds.send(dp) ;
         ds.close();
    }
}

package protocol;
import java.io.*;
import java.net.*;
public class UDPClient {
    public static void main(String[] args) throws Exception{
        DatagramSocket ds=null;
        DatagramPacket dp=null;
    //手机发信息和接收信息是有大小限制的
        byte b[]=new byte[1024];
    //在9999端口上一直等待信息到来
    ds=new DatagramSocket(9999);
    dp=new DatagramPacket(b,b.length);
    ds.receive(dp);
    //从数据包中取出数据
    String str=new String(dp.getData(),0,dp.getLength());
    System.out.println("接收到的数据为:"+str);
    ds.close();
    }
}