udpsocketsender.java

一个实用工具类

/*
 * Copyright (C) butor.com. All rights reserved.
 *
 * This software is published under the terms of the GNU Library General
 * Public License (GNU LGPL), a copy of which has been included with this
 * distribution in the LICENSE.txt file. 
 */


package org.butor.net.udp.service;
/**
 * ----------------------------------------------------------------
 * 2000jun08,deb: Initial version
 */
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
import java.net.SocketException;

import org.butor.log.Log;
/**
 * 
 *
 * @author 
 */
public class UDPSocketSender {
	public static final int DEFAULT_BUFFER_SIZE = 50;

	public static final String NULL_MSG;

	static {
		char[] chrArray = new char[1];
		chrArray[0] = '\0';

		NULL_MSG = new String(chrArray);
	}

	protected DatagramSocket f_socket = null;
	protected InetAddress f_host = null;
	protected int f_udpPort = -1;
	protected String f_hostName = null;
	protected DatagramPacket f_packet = null;
	protected String f_lastError = "";

	/**
	 * This method was created in VisualAge.
	 * @return java.lang.String
	 */
	public String getLastErrorMsg() {
		return f_lastError;
	}
	/**
	 * DatagramSender constructor comment.
	 */
	public UDPSocketSender(String hostName, int udpPort) throws SocketException {

		if (udpPort <= 0) {
			throw new SocketException("Invalid UDP port: " + udpPort);
		}

		if ((null == hostName) || (hostName.length() <= 0)) {
			Log.logStr(
				this,
				Log.LOG_TYPE_WARN,
				"DatagramSender",
				"Remote not specified, will use locahost");
		}

		f_udpPort = udpPort;
		f_hostName = hostName;

		try {
			f_host = InetAddress.getByName(hostName);
			f_socket = new DatagramSocket();

			f_packet = new DatagramPacket(new byte[0], 0, f_host, f_udpPort);

		} catch (java.net.UnknownHostException e) {
			Log.logException(this, Log.LOG_TYPE_ERROR, "UDPSender", e);

			f_lastError = e.getMessage();
			throw new SocketException(f_lastError);

		} catch (java.net.SocketException e) {
			Log.logException(this, Log.LOG_TYPE_ERROR, "UDPSender", e);

			f_lastError = e.getMessage();
			throw new SocketException(f_lastError);
		}
	}
	/**
	 * This method was created in VisualAge.
	 * @return boolean
	 * @param msg java.lang.String
	 */
	public boolean send(String msg) {
		int strLength = msg.length();

		if ((null == msg) || (strLength <= 0)) {
			Log.logStr(
				this,
				Log.LOG_TYPE_WARN,
				"send()",
				"Got NULL message to send! Sending on null char instead!");
			msg = NULL_MSG;
			strLength = msg.length();
		}

		byte[] buffer = msg.getBytes();

		f_packet.setData(buffer);
		f_packet.setLength(strLength);

		try {
			f_socket.send(f_packet);

		} catch (java.io.IOException e) {
			Log.logException(null, Log.LOG_TYPE_ERROR, "send()", e);
			f_lastError = e.getMessage();
			return false;
		}

		return true;
	}
}