UDP Sends a request to the host:port and returns the response. - Java Network

Java examples for Network:UDP

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Description

UDP Sends a request to the host:port and returns the response.

Demo Code


import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
import java.net.SocketTimeoutException;

public class Main{
    public static void main(String[] argv) throws Exception{
        String host = "java2s.com";
        int port = 2;
        String request = "java2s.com";
        System.out.println(getResponse(host,port,request));
    }/*w w  w. j a v a 2s. co  m*/
    private static final String CLASS_NAME = UDPClientUtil.class
            .getSimpleName();
    private static final int TIMEOUT = 10 * 1000;
    /**
     * Sends a request to the host:port and returns the response.
     *   
     * @param host
     * @param port
     * @param request
     * @throws IOException
     */
    public static String getResponse(String host, int port, String request)
            throws IOException {
        String method = CLASS_NAME + ".getResponse()";
        DatagramSocket socket = new DatagramSocket();
        socket.setSoTimeout(TIMEOUT);

        InetAddress addr = InetAddress.getByName(host);

        byte[] data = request.getBytes();
        DatagramPacket packet = new DatagramPacket(data, 0, data.length,
                addr, port);
        LogUtil.log(method, "Sending request: " + request);
        socket.send(packet);
        LogUtil.log(method, "DONE Sending request: " + request);

        byte[] buf = new byte[1024];
        DatagramPacket datagramPacket = new DatagramPacket(buf, 0,
                buf.length, packet.getAddress(), packet.getPort());
        LogUtil.log(method, "Waiting for response.");
        try {
            socket.receive(datagramPacket);
        } catch (SocketTimeoutException ex) {
            LogUtil.log(method,
                    "Read timed out. No response received after " + TIMEOUT
                            + "ms. Returning null.");
            return null;
        }

        String response = new String(datagramPacket.getData(), 0,
                datagramPacket.getLength());
        LogUtil.log(method, "Got response: " + response);
        socket.close();
        return response;
    }
    /**
     * Send article data gram packet to given host.
     *   
     * @param host
     * @param port
     * @param article
     * @throws IOException
     */
    public static void send(String host, int port, String article)
            throws IOException {

        DatagramSocket socket = new DatagramSocket();

        InetAddress addr = InetAddress.getByName(host);

        byte[] data = article.getBytes();
        DatagramPacket packet = new DatagramPacket(data, 0, data.length,
                addr, port);

        socket.send(packet);
        socket.close();

    }
}

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