java 网络编程

public class SendDemo {
    public static void main(String[] args) throws Exception {
        //1.创建UDP协议发送端Socket对象
        DatagramSocket ds = new DatagramSocket();

        //2.创建数据，并把数据打包
        byte[] bytes = "Hello World".getBytes();//创建要发送的数据
        int length = bytes.length;
        //创建要发送的Ip地址对象
        InetAddress address = InetAddress.getByName("127.0.0.1");
        //设置端口(1024以上)
        int port = 10110;
        //public DatagramPacket(byte buf[], int length,InetAddress address, int port)
        DatagramPacket dp = new DatagramPacket(bytes, length, address, port);

        //3.调用Socket对象的发送方法发送数据包,public void send(DatagramPacket p)
        ds.send(dp);

        //4.释放资源
        ds.close();
    }
}

public class ReceiveDemo {
    public static void main(String[] args) throws Exception {
        //1.创建UDP协议接收端Socket对象，端口号与发送端一致
        DatagramSocket ds = new DatagramSocket(10110);

        //2.创建一个数据包（接收容器）
        byte[] bytes = new byte[1024];
        int length = bytes.length;
        DatagramPacket dp = new DatagramPacket(bytes, length);

        //3.调用Socket对象的接收方法接收数据包
        ds.receive(dp);

        //4.解析数据包
        String ip = dp.getAddress().getHostAddress();//获取发送端的IP
        byte[] bytes1 = dp.getData();//获取数据缓冲区
        int length1 = dp.getLength();//获取数据实际长度
        String str = new String(bytes1, 0, length1);
        System.out.println(ip + ":" + str);//接收到的数据显示在控制台

        //5.释放资源
        ds.close();
    }
}

public class ClientDemo {
    public static void main(String[] args) throws IOException {

        //1.创建发送端的Socket对象,设置访问的IP和端口
        Socket s = new Socket(InetAddress.getByName("127.0.0.1"), 8888);

        //2.获取通道内的输出流，写数据
        OutputStream os = s.getOutputStream();
        os.write("Hello World".getBytes());
        s.shutdownOutput();//写数据完成，服务端不用在等待

        //3.获取输入流，读取返回结果
        InputStream is = s.getInputStream();
        byte[] bytes = new byte[1024];
        int len = is.read(bytes);
        String str = new String(bytes, 0, len);
        System.out.println("返回结果：" + str);

        //4.释放资源
        s.close();
    }
}

public class ServerDemo {
    public static void main(String[] args) throws IOException {

        //1.创建接收端的Socket对象
        ServerSocket ss = new ServerSocket(8888);

        while (true) {
            //2.监听客户端连接，返回一个对应的Socket对象
            Socket s = ss.accept();

            new Thread(new ClientThread(s)).start();
        }
    }
}

public class ClientThread implements Runnable {

    private Socket s;

    public ClientThread(Socket s) {
        this.s = s;
    }

    @Override
    public void run() {

        try {
            //3.获取输入流，读取数据显示在控制台
            InputStream is = null;
            is = s.getInputStream();
            byte[] bytes = new byte[1024];
            int len = is.read(bytes);
            String str = new String(bytes, 0, len);
            String ip = s.getInetAddress().getHostAddress();//获取客户端IP地址
            System.out.println(ip + ":" + str);

            //4.获取输出流，写入返回结果
            OutputStream os = s.getOutputStream();
            os.write("数据已收到".getBytes());
            //5.释放资源
            s.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}