org.commoncrawl.server.ServletRegistry.java Source code

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Here is the source code for org.commoncrawl.server.ServletRegistry.java

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/**
 * Copyright 2008 - CommonCrawl Foundation
 * 
 *    This program 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.
 *
 *    This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 **/
package org.commoncrawl.server;

import java.io.File;
import java.io.IOException;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.ArrayList;
import java.util.regex.Pattern;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.util.StringUtils;

/**
 * 
 * @author rana
 *
 */
public abstract class ServletRegistry {

    public static class DispatchVector {

        Pattern _urlPattern;

        String _className;

        DispatchVector(String pattern, String className) {
            _urlPattern = Pattern.compile(pattern);
            _className = className;
        }
    }

    public static final Log LOG = LogFactory.getLog(ServletRegistry.class);

    static void addClassPathEntries(File directory, ArrayList<URL> urlListOut) throws MalformedURLException {
        File files[] = directory.listFiles();

        if (files != null) {
            for (File file : files) {
                if (!file.isDirectory()) {
                    // LOG.info("Adding ClassPath Entry:" + file.toURL().toString());
                    urlListOut.add(file.toURI().toURL());
                } else {
                    addClassPathEntries(file, urlListOut);
                }
            }
        }
    }

    private ArrayList<DispatchVector> _registry = new ArrayList<DispatchVector>();

    public HttpServlet getServletForURI(String uri) throws ServletException, IOException {
        for (DispatchVector d : _registry) {
            if (d._urlPattern.matcher(uri).matches()) {
                // LOG.info("Loading Servlet:" + d._className + " for uri:" + uri);
                HttpServlet servlet = loadServlet(d._className);
                if (servlet != null) {

                    return servlet;
                }
            }
        }
        return null;
    }

    HttpServlet loadServlet(String servletName) {

        String classesRoot = System.getProperty("commoncrawl.classes.root");

        // LOG.info("Classes Root is:" + classesRoot);

        if (classesRoot == null) {
            classesRoot = new File("/Users/rana/commoncrawl/commoncrawl_trunk/trunk/deploy/bin").getAbsolutePath();
        }
        // LOG.info("Classes Root is:" + classesRoot);
        try {
            ArrayList<URL> urls = new ArrayList<URL>();
            urls.add(new File(classesRoot).toURI().toURL());
            LOG.info("URL is:" + urls.get(0).toString());

            addClassPathEntries(new File(classesRoot, "lib"), urls);

            DynamicClassLoader loader = new DynamicClassLoader(urls.toArray(new URL[0]),
                    ClassLoader.getSystemClassLoader(), servletName);

            // LOG.info("Loader Init Successfull");
            try {
                LOG.info("Construct class type:" + servletName);
                Class theClass = loader.loadClass(servletName, true);
                LOG.info("Loaded Class Type:" + theClass);
                return (HttpServlet) theClass.newInstance();
            } catch (ClassNotFoundException e) {
                LOG.error(StringUtils.stringifyException(e));
                throw new RuntimeException(e);
            }
        } catch (MalformedURLException e1) {
            LOG.error(StringUtils.stringifyException(e1));
        } catch (Throwable e) {
            LOG.error(StringUtils.stringifyException(e));
            throw new RuntimeException(e);
        }
        return null;
    }

    protected void registerServlet(String pathRegEx, String serveletClassName) {
        _registry.add(new DispatchVector(pathRegEx, serveletClassName));
    }
}