package com.zy.demo2;

import java.io.File;

import java.io.FileOutputStream;

import java.net.DatagramPacket;

import java.net.DatagramSocket;

import java.net.SocketException;

public class UDPReceive {

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

        //1创建码头

        DatagramSocket datagramSocket = new DatagramSocket(9999);//双方约定的

        //2创建集装箱

//        byte b[]=new byte[1024];//空的字节数组

//        DatagramPacket datagramPacket = new DatagramPacket(b, b.length);

//

//

//        //3收货

//        datagramSocket.receive(datagramPacket);//线程阻塞！！！(没收到时)        

        //-----------------------------

        byte[] aa = new byte[1];

        FileOutputStream fileOutputStream = new FileOutputStream(new File("E:\\接收的文件\\1.png"));

        do {

            DatagramPacket datagramPacket = new DatagramPacket(aa, 0, aa.length);

            if(datagramPacket.getLength()!=1){

                break;

            }

            datagramSocket.receive(datagramPacket);

            System.out.println(datagramPacket.getLength());

            fileOutputStream.write(datagramPacket.getData());

        } while (true);

        System.out.println("接收完成");

        //---------------------------------------

        //4查看货物

//        System.out.println(new String(b));

        //5释放资源

        datagramSocket.close();

    }

}

package com.zy.demo2;

import java.io.File;

import java.io.FileInputStream;

import java.io.FileOutputStream;

import java.net.DatagramPacket;

import java.net.DatagramSocket;

import java.net.InetAddress;

import java.net.UnknownHostException;

public class UDPSend {

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

        //1创建码头

        DatagramSocket datagramSocket = new DatagramSocket();

        //2创建集装箱

//        String data="中国食用油";

//        byte[] bytes = data.getBytes();

        //3发送数据

        //根据名字获取主机(机器互联)

        InetAddress byName = InetAddress.getByName("192.168.219.61");//getByName("127.0.0.1")也可以写ip，不一定非得是主机名

//        DatagramPacket datagramPacket = new DatagramPacket(bytes, bytes.length, byName, 9999);    

//        datagramSocket.send(datagramPacket);

        byte bb[]=new byte[1];//udp容易丢包，为了降低损失，字节数组调整小些

        FileInputStream fileInputStream = new FileInputStream(new File("E:\\13.png"));

        int read = fileInputStream.read(bb);

        while(read!=-1){

            DatagramPacket datagramPacket = new DatagramPacket(bb, bb.length, byName, 9999);

            datagramSocket.send(datagramPacket);

            read = fileInputStream.read(bb);

        }

        //4释放资源

        datagramSocket.close();

    }

}