UDP通信

UDP通信原理图解

 

案例：UDP数据传输

实现步骤：

发送Send

创建DatagramSocket, 随机端口号

创建DatagramPacket, 指定数据, 长度, 地址, 端口

使用DatagramSocket发送DatagramPacket

关闭DatagramSocket

 

接收Receive

创建DatagramSocket, 指定端口号

创建DatagramPacket, 指定数组, 长度

使用DatagramSocket接收DatagramPacket

关闭DatagramSocket

从DatagramPacket中获取数据

 

案例：实现UDP的发送和接收

    public static void main(String[] args) throws Exception {
//        1.发送Send
//        创建DatagramSocket, 随机端口号
        DatagramSocket sender = new DatagramSocket();
        
//        创建DatagramPacket【数据包】, 指定数据, 长度, 地址, 端口
        String s = "你好吗？最近很想你";
        byte[] bs = s.getBytes("UTF-8");
        DatagramPacket packet = new DatagramPacket(bs, bs.length, Inet4Address.getByName("192.168.1.125"), 5288);
        
//        使用DatagramSocket发送DatagramPacket
        sender.send(packet);
        
//        关闭DatagramSockets
        sender.close();
    }


public static void main(String[] args) throws IOException {
//        2.接收Receive
//        创建DatagramSocket, 指定端口号
        DatagramSocket receiver = new DatagramSocket(5288);
        
//        创建DatagramPacket, 指定数组, 长度
        byte[] buf = new byte[1024];
        DatagramPacket packet = new DatagramPacket(buf, 1024);
        
//        使用DatagramSocket接收DatagramPacket
        receiver.receive(packet);
        
//        关闭DatagramSocket
        receiver.close();
        
//        从PackeDatagramt中获取数据
        String s = new String(buf, 0, packet.getLength(), "UTF-8");
        System.out.println("接收到数据:" + s);
    }

案例：添加键盘和死循环功能

public class Demo_Sender {

    public static void main(String[] args) throws Exception {
//        1.发送Send
//        创建DatagramSocket, 随机端口号
        DatagramSocket sender = new DatagramSocket();
        
        //2 Scanner
        Scanner scanner = new Scanner(System.in);
        
        while(true){
//            创建DatagramPacket【数据包】, 指定数据, 长度, 地址, 端口
            System.out.println("输入内容：");
            String s = scanner.nextLine();
            byte[] bs = s.getBytes("UTF-8");
            DatagramPacket packet = new DatagramPacket(bs, bs.length, Inet4Address.getByName("192.168.1.125"), 5288);
            
//            使用DatagramSocket发送DatagramPacket
            sender.send(packet);
        }
        

        
//        关闭DatagramSockets
        //sender.close();
    }
}

package lesson05;
public class Demo_Receiver {

    public static void main(String[] args) throws IOException {
//        2.接收Receive
//        创建DatagramSocket, 指定端口号
        DatagramSocket receiver = new DatagramSocket(5288);
        
        while(true){
//            创建DatagramPacket, 指定数组, 长度
            byte[] buf = new byte[1024];
            DatagramPacket packet = new DatagramPacket(buf, 1024);
            
//            使用DatagramSocket接收DatagramPacket
            receiver.receive(packet);
            
//            关闭DatagramSocket
            //receiver.close();
            
//            从PackeDatagramt中获取数据
            String s = new String(buf, 0, packet.getLength(), "UTF-8");
            System.out.println(new Date() + "接收到数据:" + s);
        }
    }
}

案例：使用双线程来收发数据

public class Demo {

    public static void main(String[] args) {
        // 案例:UDP数据传输+键盘和循环+双线程实现(了解)
        new Receiver().start();
        new Sender().start();
    }
}

class Receiver extends Thread {
    @Override
    public void run() {
        // TODO Auto-generated method stub
        try {

            // 创建DatagramSocket, 指定端口号
            DatagramSocket receiver = new DatagramSocket(5288);

            while (true) {
                // 创建DatagramPacket, 指定数组, 长度
                byte[] buf = new byte[1024];
                DatagramPacket packet = new DatagramPacket(buf, 1024);

                // 使用DatagramSocket接收DatagramPacket
                receiver.receive(packet);

                // 关闭DatagramSocket
                // receiver.close();

                // 从PackeDatagramt中获取数据
                String s = new String(buf, 0, packet.getLength(), "UTF-8");
                System.out.println(new Date() + "接收到数据:" + s);
            }

        } catch (Exception e) {
            // TODO: handle exception
        }
    }
}

class Sender extends Thread {
    @Override
    public void run() {
        try {
//            创建DatagramSocket, 随机端口号
            DatagramSocket sender = new DatagramSocket();
            
            //2 Scanner
            Scanner scanner = new Scanner(System.in);
            
            while(true){
//                创建DatagramPacket【数据包】, 指定数据, 长度, 地址, 端口
                System.out.println("输入内容：");
                String s = scanner.nextLine();
                byte[] bs = s.getBytes("UTF-8");
                DatagramPacket packet = new DatagramPacket(bs, bs.length, Inet4Address.getByName("192.168.1.125"), 5288);
                
//                使用DatagramSocket发送DatagramPacket
                sender.send(packet);
            }
        } catch (Exception e) {
            // TODO: handle exception
        }
    }
}