org.polymap.core.http.HttpServiceTracker.java Source code

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Here is the source code for org.polymap.core.http.HttpServiceTracker.java

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/* 
 * polymap.org
 * Copyright 2009-2012, Polymap GmbH, and individual contributors as indicated
 * by the @authors tag.
 *
 * This is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation; either version 2.1 of
 * the License, or (at your option) any later version.
 *
 * This software 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
 * Lesser General Public License for more details.
 */
package org.polymap.core.http;

import java.util.Dictionary;

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

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import org.osgi.framework.BundleContext;
import org.osgi.framework.ServiceReference;
import org.osgi.service.http.HttpContext;
import org.osgi.service.http.HttpService;
import org.osgi.service.http.NamespaceException;
import org.osgi.util.tracker.ServiceTracker;

import org.eclipse.core.runtime.IConfigurationElement;
import org.eclipse.core.runtime.Platform;

import org.polymap.core.CorePlugin;

/**
 * Tracks the {@link HttpService}. When a HttpService is available then it
 * initializes servlets registered via the {@link #SERVLETS_EXTENSION_POINT_ID}.
 * <p/>
 * This also provides a facade to the {@link HttpService} that might be used for
 * better argument checking and error handling.
 * 
 * @author <a href="http://www.polymap.de">Marcus -LiGi- Bueschleb</a>
 * @author <a href="http://www.polymap.de">Falko Braeutigam</a>
 * @since 3.0
 */
public class HttpServiceTracker extends ServiceTracker {

    private static final Log log = LogFactory.getLog(HttpServiceTracker.class);

    private static final String SERVLETS_EXTENSION_POINT_ID = CorePlugin.PLUGIN_ID + ".http.servlets";

    private HttpService httpService;

    public HttpServiceTracker(BundleContext context) {
        super(context, HttpService.class.getName(), null);
    }

    public HttpService getHttpService() {
        return httpService;
    }

    public Object addingService(ServiceReference reference) {
        HttpService _httpService = (HttpService) super.addingService(reference);
        if (httpService == null && _httpService != null) {
            httpService = _httpService;
            init();
        }
        return httpService;
    }

    protected void init() {
        assert httpService != null;

        // servlet extensions ******
        IConfigurationElement[] exts = Platform.getExtensionRegistry()
                .getConfigurationElementsFor(SERVLETS_EXTENSION_POINT_ID);
        log.debug("servlet extensions found: " + exts.length);

        for (IConfigurationElement ext : exts) {
            try {
                String path = ext.getAttribute("path");
                String contextPath = ext.getAttribute("contextPath");
                if (contextPath != null && !contextPath.startsWith("/")) {
                    contextPath = "/" + contextPath;
                }

                HttpServlet servlet = (HttpServlet) ext.createExecutableExtension("class");
                httpService.registerServlet(path, servlet, null, null);
                log.debug("    context: " + contextPath + " :" + servlet.getClass().getName());
            } catch (Exception e) {
                CorePlugin.logError("Error while starting servlet extension: " + ext.getName(), log, e);
            }
        }
    }

    public HttpContext createDefaultHttpContext() {
        return httpService.createDefaultHttpContext();
    }

    public void registerResources(String alias, String name, @SuppressWarnings("hiding") HttpContext context)
            throws NamespaceException {
        httpService.registerResources(alias, name, context);
    }

    public void registerServlet(String alias, Servlet servlet, Dictionary initparams,
            @SuppressWarnings("hiding") HttpContext context) throws ServletException, NamespaceException {
        httpService.registerServlet(alias, servlet, initparams, context);
    }

    public void unregister(String alias) {
        httpService.unregister(alias);
    }

}