UDP消息发送

UDP

• 发短信 : 不需要连接但是需要知道对方的地址

  发送消息

//不需要连接服务器
public static void main(String[] args) throws Exception {
    //1.建立一个socket
    DatagramSocket datagramSocket = new DatagramSocket();
    //2.建个包
    String msg = "你好";

    InetAddress localhost = InetAddress.getByName("localhost");
    int port = 9090;
    //数据，数据长度起始，发送给谁
    DatagramPacket datagramPacket = new DatagramPacket(msg.getBytes(), 0, msg.getBytes().length,localhost,port);
    //3.发送包
    datagramSocket.send(datagramPacket);
    //关闭流
    datagramSocket.close();
}

接收端

public static void main(String[] args) throws Exception {
    //开放端口
    DatagramSocket datagramSocket = new DatagramSocket(9090);
    //接受数据包
    byte[] bytes = new byte[1024];
    DatagramPacket datagramPacket = new DatagramPacket(bytes, 0, bytes.length);
    datagramSocket.receive(datagramPacket);
    System.out.println(datagramPacket.getAddress().getHostAddress());
    System.out.println(new String(datagramPacket.getData(),0,datagramPacket.getLength()));
    //关闭连接
    datagramSocket.close();
}