Java网络编程UDP协议发送接收数据

UDP协议发送数据步骤

A：创建发送端socket对象；

B：创建数据，并把数据打包；

C：调用socket对象的发送方法发送数据包；

D：释放资源

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();
		
	}
}

UDP协议接收数据步骤

A：创建接收端socket对象；

B：创建一个数据包（接收容器）；

C：调用socket对象的接收方法接收数据；

D：解析数据，显示到控制台；

E：释放资源

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();
	}
}

先运行接收端代码，再运行发送端代码。

多次从键盘接收发送数据版本

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();
	}
}