UDP
UDP是一种面向无连接的协议,因此传输过程中不能保证数据的完整性。jdk提供了网络通信包,在java.net包下提供了两个类DatagramPacket和DatagramSocket来实现UDP通信。这两个类可以这样理解,DatagramSocket是路,DatagramPacket路上装有人的车。也就是DatagramSocket决定了通信目标,DatagramPacket则代表封装好的数据。
UDP的特性决定了UDP协议的应用场景,在我身边最常见的应用场景就是物联网设备与服务端的通信。
UDPClient实现
- public class UDPClient {
- public static void main(String[] args) throws Exception {
- byte[] data = "我是客户端,我发送了一条消息".getBytes();
- InetAddress address = InetAddress.getByName("localhost");
- DatagramPacket packet = new DatagramPacket(data,data.length,address,8888);
- DatagramSocket socket = new DatagramSocket();
- socket.send(packet);
- byte[] message = new byte[1024];
- DatagramPacket packet1 = new DatagramPacket(message,message.length);
- socket.receive(packet1);
- String replyContent = new String(message,0,message.length);
- System.out.println("UDPClient 接收到了消息:"+replyContent);
- socket.close();
- }
- }
UDPServer实现
- public class UDPServer {
- public static void main(String[] args) throws Exception {
- DatagramSocket socket = new DatagramSocket(8888);
- byte[] data = new byte[1024];
- DatagramPacket packet = new DatagramPacket(data,data.length);
- socket.receive(packet);
- String message = new String(data,0,packet.getLength());
- System.out.println("UDPServer 接收到了消息:"+message);
- InetAddress address = packet.getAddress();
- int port = packet.getPort();
- byte[] replyContent = "我是服务端,我回复了一条消息".getBytes();
- DatagramPacket packet1 = new DatagramPacket(replyContent, replyContent.length, address, port);
- socket.send(packet1);
- socket.close();
- }
- }
TCP
TCP是一种面向连接的服务,经过三次握手建立连接,通过传输字节流的方式进行通信。因此可以保证消息的完整性。同样,在java.net包下也提供了两个包Socket和ServerSocket来实现TCP通信。
TCPClient
- public class TCPClient {
- public static void main(String[] args) throws Exception {
- Socket socket = new Socket("localhost",8081);
- DataOutputStream out = new DataOutputStream(socket.getOutputStream());
- String data = "我是客户端,我发了一条消息";
- out.writeUTF(data);
- DataInputStream in = new DataInputStream(socket.getInputStream());
- String message = in.readUTF();
- System.out.println("TCPClient:"+message);
- socket.close();
- }
- }
TCPServer
- public class TCPServer {
- public static void main(String[] args) throws Exception{
- ServerSocket serverSocket = new ServerSocket(8081);
- Socket socket = serverSocket.accept();
- DataInputStream in = new DataInputStream(socket.getInputStream());
- String message = in.readUTF();
- System.out.println("TCPServer:"+message);
- DataOutputStream out = new DataOutputStream(socket.getOutputStream());
- out.writeUTF("我是服务器,我回复了一条消息");
- socket.close();
- serverSocket.close();
- }
- }
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