Java网络编程之Socket

Java网络编程之Socket

什么是Socket

通常也称作”套接字“，用于描述IP地址和端口，是一个通信链的句柄。应用程序通常通过”套接字”向网络发出请求或者应答网络请求。

TCP与UDP的区别

• TCP是一种面向连接的保证可靠传输的协议，可靠，效率稍低；
• UDP是一种无连接的协议，不可靠，效率高；
• 建立起一个TCP连接需要经过“三次握手”；
• TCP传输数据没有大小限制；
• UDP的每个数据报中都给出了完整的地址信息；
• UDP传输数据时是有大小限制的，每个被传输的数据报必须限定在64KB之内；

TCP连接的三次握手

Java Udp实现

服务端：

public class UdpServer {

    private Integer port;

    public UdpServer(Integer port) {
        this.port = port;
    }

    public void start() throws IOException {
        System.out.println("UDP服务端启动");
        DatagramSocket socket = new DatagramSocket(this.port);
        byte[] bytes = new byte[1024];
        DatagramPacket packet = new DatagramPacket(bytes, bytes.length);
        //等待客户端发送内容，若客户端不发送则一直等待，阻塞效果
        socket.receive(packet);
        String data = new String(packet.getData(), packet.getLength());
        System.out.println("服务端收到数据：" + data);
        socket.close();
    }
}

客户端：

public class UdpClient {

    private Integer port;

    public UdpClient(Integer port) {
        this.port = port;
    }

    public void start(String targetIp, Integer targetPort) throws IOException {
        System.out.println("UDP客户端启动");
        DatagramSocket socket = new DatagramSocket(this.port);
        String data = "hello world";
        DatagramPacket packet = new DatagramPacket(data.getBytes(), data.getBytes().length, InetAddress.getByName(targetIp), targetPort);
        System.out.println("UDP客户端发送消息");
        socket.send(packet);
        socket.close();
    }

}

运行：

public static void main(String[] args) throws IOException, InterruptedException {
    Integer serverPort = 15367;
    Integer clientPort = 15369;
    new Thread(new Runnable() {
        @SneakyThrows
        @Override
        public void run() {
            UdpServer server = new UdpServer(serverPort);
            server.start();
        }
    }).start();
    Thread.sleep(1000);
    new Thread(new Runnable() {
        @SneakyThrows
        @Override
        public void run() {
            UdpClient client = new UdpClient(clientPort);
            client.start("127.0.0.1", serverPort);
        }
    }).start();
}

Java Tcp实现

服务端：

public class TcpServer {

    private Integer port;

    public TcpServer(Integer port) {
        this.port = port;
    }

    public void start() throws IOException {
        System.out.println("Tcp服务端启动");
        ServerSocket serverSocket = new ServerSocket(this.port);
        try {
            //等待客户端连接，阻塞状态
            Socket accept = serverSocket.accept();
            InputStream is = accept.getInputStream();
            byte[] bytes = new byte[1024];
            int len = is.read(bytes);
            String data = new String(bytes, 0, len);
            System.out.println("服务端接收到数据：" + data);
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            serverSocket.close();
        }
    }
}

客户端：

public class TcpClient {

    @MetaData(name = "服务端ip")
    private String ip;
    @MetaData(name = "服务端端口")
    private Integer port;

    public TcpClient(String ip, Integer port) {
        this.ip = ip;
        this.port = port;
    }

    public void start() throws IOException {
        System.out.println("Tcp客户端启动");
        Socket socket = new Socket(this.ip, this.port);
        try {
            System.out.println("Tcp客户端发送消息");
            OutputStream os = socket.getOutputStream();
            String data = "hello world";
            os.write(data.getBytes());
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            socket.close();
        }
    }
}

运行：

public static void main(String[] args) throws InterruptedException {
    Integer port = 16487;
    new Thread(new Runnable() {
        @SneakyThrows
        @Override
        public void run() {
            TcpServer server = new TcpServer(port);
            server.start();
        }
    }).start();
    Thread.sleep(1000);
    new Thread(new Runnable() {
        @SneakyThrows
        @Override
        public void run() {
            TcpClient client = new TcpClient("127.0.0.1", port);
            client.start();
        }
    }).start();
}