webutils.java

来自「spam source codejasen-0.9jASEN - java An」· Java 代码 · 共 142 行

/*
 * @(#)WebUtils.java	11/11/2004
 *
 * Copyright (c) 2004, 2005  jASEN.org
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 *   1. Redistributions of source code must retain the above copyright notice,
 *      this list of conditions and the following disclaimer.
 *
 *   2. Redistributions in binary form must reproduce the above copyright
 *      notice, this list of conditions and the following disclaimer in
 *      the documentation and/or other materials provided with the distribution.
 *
 *   3. The names of the authors may not be used to endorse or promote products
 *      derived from this software without specific prior written permission.
 *
 *   4. Any modification or additions to the software must be contributed back
 *      to the project.
 *
 *   5. Any investigation or reverse engineering of source code or binary to
 *      enable emails to bypass the filters, and hence inflict spam and or viruses
 *      onto users who use or do not use jASEN could subject the perpetrator to
 *      criminal and or civil liability.
 *
 * THIS SOFTWARE IS PROVIDED "AS IS" AND ANY EXPRESSED OR IMPLIED WARRANTIES,
 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
 * FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL JASEN.ORG,
 * OR ANY CONTRIBUTORS TO THIS SOFTWARE BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA,
 * OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
 * EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 */
package org.jasen.util;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.MalformedURLException;
import java.net.URL;
import org.jasen.io.NonBlockingStreamReader;
import org.jasen.io.StreamReaderListener;

/**
 * <P>
 * 	General WWW and net utility methods.
 * </P>
 * @author Jason Polites
 */
public class WebUtils
{

    public static final String URL_REGEX = "";

    /**
     * Returns true iff the text passed represents a url.
     * <p>
     * A url may take many forms:
     * <br/><br/>
     * For example:
     * <ul>
     * 	<li/>www.google.com
     * 	<li/>http://www.google.com
     * 	<li/>google.com
     * 	<li/>toolbar.google.com
     * 	<li/>a.b.c.d.e.f.g.google.com
     * 	<li/>etc...
     * </ul>
     * </p>
     * <p>
     * Unfortunately there doesn't seem to be an "elegant" way to determine<br/>
     * definatively if an unknown String is in fact a URL.  We are just going<br/>
     * to use the java.net.URL class and assume a MalformedURLException implies<br/>
     * that the string is not a url.
     * </p>
     * @param text
     * @return True if the text is a valid URL, false otherwise
     */
    public static boolean isUrl(String text) {
        try
        {
            URL u = new URL(text);
            return true;
        }
        catch (MalformedURLException e)
        {
            return false;
        }
    }
    
    /**
     * Attempts to download the file given by the URL and saves it to the output stream provided
     * <br/>
     * NOTE: The given output stream will NOT be closed within this method
     * @param url The fully qualified url path to the remote resource
     * @param out The output stream to which the data read will be written
     * @param bufferSize The buffer size to use for reading bytes
     * @param timeout The timeout (in milliseconds) to wait for a response from the remote server
     * @throws IOException If an error occurred during transit
     */    
    public static void get(URL url, OutputStream out, int bufferSize, long timeout) throws IOException {
        get(url, out, bufferSize, timeout, null);
    }

    /**
     * Attempts to download the file given by the URL and saves it to the output stream provided
     * <br/>
     * NOTE: The given output stream will NOT be closed within this method
     * @param url The fully qualified url path to the remote resource
     * @param out The output stream to which the data read will be written
     * @param bufferSize The buffer size to use for reading bytes
     * @param timeout The timeout (in milliseconds) to wait for a response from the remote server
     * @param listener A listener which will report when bytes have been written to the output stream
     * @throws IOException If an error occurred during transit
     */
    public static void get(URL url, OutputStream out, int bufferSize, long timeout, StreamReaderListener listener) throws IOException {

		InputStream in = null;
		NonBlockingStreamReader reader = null;

		try {
			in = url.openConnection().getInputStream();
			reader = new NonBlockingStreamReader(listener);
			reader.read(in, out, bufferSize, timeout, null);
		}
		finally {
			if(in != null) {
				try {
					in.close();
				}
				catch (IOException ignore) {}
			}
		}
    }
}