Java网络编程UDP协议发送接收数据

package net;
 
import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
 
public class SendDemo {
 public static void main(String[] args) throws IOException {
  //A
  DatagramSocket ds = new DatagramSocket();
  
  //B
  byte[] by = "Hello,UDP".getBytes();
  int length = by.length;
  InetAddress addr = InetAddress.getByName("192.168.1.22");
  int port = 10010;
  DatagramPacket dp = new DatagramPacket(by, length, addr, port);
  
  //C
  ds.send(dp);
  
  //D
  ds.close();
  
 }
}

package net;
 
import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
 
public class ReceiveDemo {
 public static void main(String[] args) throws IOException {
  //A
  DatagramSocket ds = new DatagramSocket(10010);
  
  //B
  byte[] by = new byte[1024];
  int length = by.length;
  DatagramPacket dp = new DatagramPacket(by, length);
  
  //C
  ds.receive(dp);
  
  //D
  //获取对方ip
  InetAddress addr = dp.getAddress();
  String ip = addr.getHostAddress();
  byte[] by2 = dp.getData();
  int len = by2.length;
  String s = new String(by2, 0, len);
  System.out.println(ip+"发送的数据是："+s);
  
  //E
  ds.close();
 }
}

package net;
 
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
 
public class SendDemo {
 public static void main(String[] args) throws IOException {
  //A
  DatagramSocket ds = new DatagramSocket();
  //数据来自键盘录入
  BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
  String line = null;
  while((line = br.readLine()) != null){
   //当输入jieshu时，结束
   if("jieshu".equals(line)){
    break;
   }
   //B
   byte[] by = line.getBytes();
   int length = by.length;
   InetAddress addr = InetAddress.getByName("192.168.1.22");
   int port = 10010;
   DatagramPacket dp = new DatagramPacket(by, length, addr, port);
    
   //C
   ds.send(dp);
  }
  //D
  ds.close();
  
 }
}

package net;
 
import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
 
public class ReceiveDemo {
 public static void main(String[] args) throws IOException {
  //A
  DatagramSocket ds = new DatagramSocket(10010);
  //多次接受版本
  while(true){
   //B
   byte[] by = new byte[1024];
   int length = by.length;
   DatagramPacket dp = new DatagramPacket(by, length);
   
   //C
   ds.receive(dp);
   
   //D
   //获取对方ip
   InetAddress addr = dp.getAddress();
   String ip = addr.getHostAddress();
   byte[] by2 = dp.getData();
   int len = by2.length;
   String s = new String(by2, 0, len);
   System.out.println(ip+"发送的数据是："+s);
  }
  
  //E
  //ds.close();
 }
}