Detailed explanation of the sender and receiver examples of simulating UDP transmission in Java

import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;

public class UDPSend {

 public static void main(String[] args) throws IOException {

  System.out.println("发送端启动......");

  // 1、创建UDP的Socket，使用DatagramSocket对象
  DatagramSocket ds = new DatagramSocket();

  // 2、将要发送的数据封装到数据包中
  String str = "UDP传输演示：I'm coming!";

  byte[] buf = str.getBytes(); //使用DatagramPacket将数据封装到该对象的包中

  DatagramPacket dp = new DatagramPacket(buf, buf.length, InetAddress.getByName("192.168.191.1"), 10000);

  // 3、通过UDP的Socket服务将数据包发送出去，使用send方法
  ds.send(dp);

  // 4、关闭Socket服务
  ds.close();
 }
}

import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;

public class UDPReceive {
 public static void main(String[] args) throws IOException {

  System.out.println("接收端启动......");

  // 1、建立UDP的Socket服务
  DatagramSocket ds = new DatagramSocket(10000);

  // 2、创建数据包
  byte[] buf = new byte[1024];
  DatagramPacket dp = new DatagramPacket(buf, buf.length);

  // 3、使用接收方法将数据存储到数据包中
  ds.receive(dp); // 该方法为阻塞式的方法

  // 4、通过数据包对象的方法解析这些数据，例如：地址、端口、数据内容等
  String ip = dp.getAddress().getHostAddress();
  int port = dp.getPort();
  String text = new String(dp.getData(), 0, dp.getLength());

  System.out.println(ip + ":" + port + ":" + text);

  // 5、关闭Socket服务
  ds.close();
 }
}

/**
*优化UDP传输的发送端
*/
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 UDPSend {
 public static void main(String[] args) throws IOException {

  System.out.println("发送端启动......");

  // 创建UDP的Socket，使用DatagramSocket对象
  DatagramSocket ds = new DatagramSocket();

  BufferedReader bufr = new BufferedReader(new InputStreamReader(System.in));
  String line = null;
  while ((line = bufr.readLine()) != null) {
   // 使用DatagramPacket将数据封装到该对象的包中
   byte[] buf = line.getBytes();
   DatagramPacket dp = new DatagramPacket(buf, buf.length, InetAddress.getByName("192.168.191.1"), 10000);
   // 通过UDP的Socket服务将数据包发送出去，使用send方法
   ds.send(dp);
   // 如果输入信息为over，则结束循环
   if ("over".equals(line))
    break;
  }
  // 关闭Socket服务
  ds.close();
 }
}

/**
*优化UDP传输的接收端
*/
import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;

public class UDPReceive {
 public static void main(String[] args) throws IOException {

  System.out.println("接收端启动......");

  // 建立UDP的Socket服务
  DatagramSocket ds = new DatagramSocket(10000);

  while(true) {
   // 创建数据包
   byte[] buf = new byte[1024];
   DatagramPacket dp = new DatagramPacket(buf, buf.length);

   // 使用接收方法将数据存储到数据包中
   ds.receive(dp); // 该方法为阻塞式的方法

   // 通过数据包对象的方法解析这些数据，例如：地址、端口、数据内容等
   String ip = dp.getAddress().getHostAddress();

   int port = dp.getPort();
   String text = new String(dp.getData(), 0, dp.getLength());
   System.out.println(ip + ":" + port + ":" + text);
  }
 }
}

/**
*创建UDP传输下的聊天室发送端
*/
package chat;

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;

public class Send implements Runnable {

 private DatagramSocket ds;

 public Send(DatagramSocket ds) {
  this.ds = ds;
 }

 public void run() {
  try {
   BufferedReader bufr = new BufferedReader(new InputStreamReader(System.in));
   String line = null;
   while ((line = bufr.readLine()) != null) {
    byte[] buf = line.getBytes();
    DatagramPacket dp = new DatagramPacket(buf, buf.length, InetAddress.getByName("192.168.191.255"), 10001);
    ds.send(dp);
    if ("886".equals(line))
     break;
   }
   ds.close();
  } catch (Exception e) {
   System.out.println("对不起，发生错误啦！");
  }
 }
}

/**
*创建UDP传输下的聊天室接收端
*/
package chat;

import java.net.DatagramPacket;
import java.net.DatagramSocket;

public class Rece implements Runnable {

 private DatagramSocket ds;

 public Rece(DatagramSocket ds) {
  this.ds = ds;
 }

 public void run() {
  try {
   while (true) {
    byte[] buf = new byte[1024];
    DatagramPacket dp = new DatagramPacket(buf, buf.length);
    ds.receive(dp);
    String ip = dp.getAddress().getHostAddress();
    String text = new String(dp.getData(), 0, dp.getLength());
    System.out.println(ip + ":::" + text);
    if(text.equals("886")){
     System.out.println(ip+"......退出聊天室！");
    }
   }
  } catch (Exception e) {
   System.out.println("对不起，发生错误啦！");
  }
 }
}

/**
*创建UDP传输下的聊天室
*/
package chat;

import java.io.IOException;
import java.net.DatagramSocket;

public class ChatRoom {
 public static void main(String[] args) throws IOException {
  DatagramSocket send = new DatagramSocket();
  DatagramSocket rece = new DatagramSocket(10001);
  new Thread(new Send(send)).start();
  new Thread(new Rece(rece)).start();
 }
}