1 UDP通信

客户端UDPClient

public class UDPClient {
    public static void main(String[] args) throws IOException {
        // 获取本地服务器地址
        InetAddress server_address = InetAddress.getLocalHost();
        // 创建数据报套接字以连接到服务器
        DatagramSocket client = new DatagramSocket();

        Scanner sc = new Scanner(System.in);
        while (true) {
            System.out.println("please enter:");
            String s = sc.nextLine();
            if (s.equals("exit")) {
                break;
            }
            byte[] bytes = s.getBytes();

            // 创建数据报包以发送消息到服务器
            DatagramPacket sendPacket = new DatagramPacket(bytes, bytes.length, server_address, 8080);
            client.send(sendPacket);
        }
    }
}

服务端UDPSerever

public class UDPServer {
    public static void main(String[] args) throws IOException {
        // 创建一个数据报套接字，并将其绑定到端口8080，用于监听来自客户端的请求
        DatagramSocket server = new DatagramSocket(8080);

        byte[] buffer = new byte[1024];
        // 创建一个数据报包，用于接收客户端发送的数据，指定接收缓冲区和缓冲区长度
        DatagramPacket receivePacket = new DatagramPacket(buffer, buffer.length);

        while (true) {
            // 接收数据报包中的数据
            server.receive(receivePacket);
            int len = receivePacket.getLength();
            String data = new String(receivePacket.getData(), 0, len);
            String ip = receivePacket.getAddress().getHostAddress();
            int port = receivePacket.getPort();
            System.out.println("Received: " + "[ip " + ip + " port " + port + "] " + data);
        }

    }
}

2 TCP通信

客户端TCPClient

public class TCPClient {
    public static void main(String[] args) throws IOException {
        Socket socket = new Socket("127.0.0.1", 9999);

        OutputStream os = socket.getOutputStream();
        DataOutputStream dos = new DataOutputStream(os);

        Scanner scanner = new Scanner(System.in);
        while (true) {
            System.out.println("please enter:");
            String s = scanner.nextLine();
            if (s.equals("exit")) {
                socket.close();
                break;
            }
            dos.writeUTF(s);
            dos.flush();
        }
    }
}

服务端TCPServer

public class TCPServer {
    public static void main(String[] args) throws IOException {
        ServerSocket serverSocket = new ServerSocket(9999);

        Socket socket = serverSocket.accept();

        InputStream is = socket.getInputStream();
        DataInputStream dis = new DataInputStream(is);

        while (true) {
            String s = dis.readUTF();
            System.out.println("ip " + socket.getInetAddress().getHostAddress() + " port "+ socket.getPort() + " " + s);
            System.out.println("--------------");
        }

    }
}

服务端TCPServerMultiThread（多线程）

public class TCPServerMultiThread {
    public static void main(String[] args) throws IOException {
        // 主线程负责接收客户端连接
        ServerSocket serverSocket = new ServerSocket(9999);
        while(true){
            Socket accept = serverSocket.accept();
            System.out.println("online-UP: ip " + accept.getInetAddress().getHostAddress() + " port "+ accept.getPort());
            // 创建子线程并启动
            new ServerThread(accept).start();
        }
    }
}

class ServerThread extends Thread{
    private Socket socket;

    public ServerThread(Socket socket) {
        this.socket = socket;
    }

    @Override
    public void run() {
        try {
            InputStream is = socket.getInputStream();
            DataInputStream dis = new DataInputStream(is);

            while (true) {
                String s = dis.readUTF();
                System.out.println("ip " + socket.getInetAddress().getHostAddress() + " port "+ socket.getPort() + " " + s);
                System.out.println("--------------");
            }
        } catch (IOException e) {
            System.out.println("offline-DOWN: ip " + socket.getInetAddress().getHostAddress() + " port "+ socket.getPort());
            e.printStackTrace();
        }
    }
}