de.innovationgate.contentmanager.modules.LinkChecker.java Source code

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Here is the source code for de.innovationgate.contentmanager.modules.LinkChecker.java

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/*******************************************************************************
 * Copyright 2009, 2010 Innovation Gate GmbH. All Rights Reserved.
 * 
 * This file is part of the OpenWGA server platform.
 * 
 * OpenWGA is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 * 
 * In addition, a special exception is granted by the copyright holders
 * of OpenWGA called "OpenWGA plugin exception". You should have received
 * a copy of this exception along with OpenWGA in file COPYING.
 * If not, see <http://www.openwga.com/gpl-plugin-exception>.
 * 
 * OpenWGA is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with OpenWGA in file COPYING.
 * If not, see <http://www.gnu.org/licenses/>.
 ******************************************************************************/
package de.innovationgate.contentmanager.modules;

import java.io.IOException;

import org.apache.commons.httpclient.Header;
import org.apache.commons.httpclient.HttpClient;
import org.apache.commons.httpclient.HttpException;
import org.apache.commons.httpclient.URI;
import org.apache.commons.httpclient.methods.GetMethod;

import de.innovationgate.webgate.api.WGFactory;

public class LinkChecker {

    private static final int DEFAULT_MAX_REDIRECTS = 10;

    private int _maxRedirects = DEFAULT_MAX_REDIRECTS;

    /**
     * checks if the given URL is reachable and returns the response code
     * redirects of type 301, 302, 303 and 307 are followed <code>getMaxRedirects()</code> times automatically 
     * @param uri the uri to check
     * @return HTTP reponse code
     * @throws IOException 
     * @throws HttpException 
     * @throws IllegalStateException if max redirects has been reached
     */
    public int check(String uri) throws HttpException, IOException {
        HttpClient client = WGFactory.getHttpClientFactory().createHttpClient();
        return innerCheck(client, new URI(uri, true), 0);
    }

    private int innerCheck(HttpClient client, URI uri, int redirectCounter) throws HttpException, IOException {
        if (redirectCounter >= DEFAULT_MAX_REDIRECTS) {
            throw new IllegalStateException(
                    "Max redirects '" + DEFAULT_MAX_REDIRECTS + "' reached. Might be an endless redirect.");
        }
        GetMethod targetGET = new GetMethod();
        targetGET.setURI(uri);
        targetGET.setFollowRedirects(false);
        int result = client.executeMethod(targetGET);
        if (result == 301 || result == 302 || result == 303 || result == 307) {
            // follow redirect
            Header locationHeader = targetGET.getResponseHeader("location");
            if (locationHeader != null) {
                String redirectLocation = locationHeader.getValue();
                targetGET.releaseConnection();
                return innerCheck(client, new URI(uri, redirectLocation, true), redirectCounter + 1);
            } else {
                targetGET.releaseConnection();
                return 404;
            }
        } else {
            targetGET.releaseConnection();
            return result;
        }
    }

    /**
     * returns max redirects for uri checks
     * @return
     */
    public int getMaxRedirects() {
        return _maxRedirects;
    }

    /**
     * sets max redirects for uri checks
     * @param maxRedirects follow redirects n times
     */
    public void setMaxRedirects(int maxRedirects) {
        _maxRedirects = maxRedirects;
    }

}