1
try {
2
    // 获取本机的InetAddress对象
3
    InetAddress address = InetAddress.getLocalHost();
4
    System.out.println(address);
5
    System.out.println(address.getHostAddress());
6

7
    // 获取某对方的InetAddress对象
8
    InetAddress address2 = InetAddress.getByName("www.baidu.com");
9
    System.out.println(address2);
10
    System.out.println(address2.getHostAddress());
11

12
    // ping 判断本机与对方是否互通
13
    System.out.println(InetAddress.getByName("www.baidu.com").isReachable(3000));
14
} catch (Exception e) {
15
    e.printStackTrace();
16
}

1
public class UDPServer01 {
2
    public static void main(String[] args) throws Exception{
3
        System.out.println("服务器端已经启动...");
4
        //1.创建一个DatagramSocket对象，并指定端口号
5
        DatagramSocket socket = new DatagramSocket(8080);
6
        //2.创建一个DatagramPacket对象，用于接收数据包
7
        byte[] buf = new byte[1024];
8
        DatagramPacket packet = new DatagramPacket(buf, buf.length);
9
        //3.调用DatagramSocket对象的receive方法，接收数据包
10
        socket.receive(packet);
11
        //4.获取数据包中的数据，并显示
12
        String msg = new String(packet.getData(), 0, packet.getLength());
13
        System.out.println(msg);
14
        // 5.获取数据包中的发送端的IP地址和端口号
15
        System.out.println(packet.getAddress().getHostAddress() + ":" + packet.getPort());
16
        socket.close();
17
    }
18
}

1
public static void main(String[] args) throws Exception {
2
    System.out.println("客户端启动...");
3
    // 1. 创建发送端套接字
4
    DatagramSocket socket = new DatagramSocket();
5
    Scanner sc = new Scanner(System.in);
6
    while (true) {
7
        System.out.println("请输入要发送的数据：");
8
        String str = sc.nextLine();
9
        if ("886".equals(str)) {
10
            System.out.println("客户端退出...");
11
            socket.close();
12
            break;
13
        }
14
        byte[] data = str.getBytes();
15
        DatagramPacket packet = new DatagramPacket(data, data.length, InetAddress.getByName("127.0.0.1"), 8080);
16
        socket.send(packet);
17
    }
18
}

1
public class TCPServer01 {
2
    public static void main(String[] args) throws Exception {
3
        System.out.println("服务器启动...");
4
        //1.创建一个服务器Socket，即ServerSocket，指定绑定的端口，并监听此端口
5
        ServerSocket serverSocket = new ServerSocket(8080);
6
        //2.调用accept()方法开始监听，阻塞等待客户端的连接
7
        java.net.Socket socket= serverSocket.accept();
8
        //3.获取输入流，并读取客户端信息
9
        InputStream inputStream = socket.getInputStream();
10
        //特殊数据输入流
11
        DataInputStream dis = new DataInputStream(inputStream);
12
        String name = dis.readUTF();
13
        int age = dis.readInt();
14
        System.out.println("name="+name+",age="+age);
15
        System.out.println("Client is "+socket.getInetAddress()+ " : " +socket.getPort());
16
    }
17
}

1
public static void main(String[] args) throws Exception {
2
    System.out.println("客户端启动....");
3
    Socket socket = new Socket("127.0.0.1",8080);
4
    OutputStream os = socket.getOutputStream();
5
    // 特殊数据流
6
    DataOutputStream dos = new DataOutputStream(os);
7
    Scanner sc = new Scanner(System.in);
8
    while (true) {
9
        System.out.println("请输入：");
10
        String msg = sc.nextLine();
11
        if ("886".equals(msg)) {
12
            System.out.println("客户端退出...");
13
            socket.close();
14
            break;
15
        }
16
        dos.writeUTF(msg);
17
        dos.flush();
18
    }
19
}

1
public class TCPServer01 {
2
    public static void main(String[] args) throws Exception {
3
        System.out.println("服务器启动...");
4
        ServerSocket serverSocket = new ServerSocket(8080);
5

6
        while (true) {
7
            Socket socket= serverSocket.accept();
8
            System.out.println("Client is online " + socket.getRemoteSocketAddress() + ":" + socket.getPort());
9
            // 2. 把客户端请求交给一个子线程处理
10
            new ServerThread(socket).start();
11
        }
12

13
    }
14
}
15
class ServerThread extends Thread {
16
    private Socket socket;
17

18
    public ServerThread(Socket socket) {
19
        this.socket = socket;
20
    }
21

22
    @Override
23
    public void run() {
24
        try {
25
            // 3. 从socket中获取一个输入流，并读取客户端发送的数据
26
            InputStream inputStream = socket.getInputStream();
27
            DataInputStream dataInputStream = new DataInputStream(inputStream);
28
            while (true) {
29
                String msg = dataInputStream.readUTF();
30
                System.out.println("服务器接收到数据：" + msg);
31
            }
32
        } catch (Exception e) {
33
            System.out.println("客户端" + socket.getRemoteSocketAddress() + ":" + socket.getPort() + "断开连接");
34
        }
35
    }
36
}