001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017package org.apache.wicket.protocol.http;
018
019import java.lang.reflect.InvocationTargetException;
020
021import org.apache.wicket.WicketRuntimeException;
022
023/**
024 * Factory that creates application objects based on the class name specified in the
025 * {@link ContextParamWebApplicationFactory#APP_CLASS_PARAM} context variable.
026 * 
027 * @author Igor Vaynberg (ivaynberg)
028 */
029public class ContextParamWebApplicationFactory implements IWebApplicationFactory
030{
031        /**
032         * context parameter name that must contain the class name of the application
033         */
034        public static final String APP_CLASS_PARAM = "applicationClassName";
035
036        /* @see IWebApplicationFactory#createApplication(WicketFilter) */
037        @Override
038        public WebApplication createApplication(WicketFilter filter)
039        {
040                final String applicationClassName = filter.getFilterConfig().getInitParameter(
041                        APP_CLASS_PARAM);
042
043                if (applicationClassName == null)
044                {
045                        throw new WicketRuntimeException(
046                                "servlet init param [" +
047                                        APP_CLASS_PARAM +
048                                        "] is missing. If you are trying to use your own implementation of IWebApplicationFactory and get this message then the servlet init param [" +
049                                        WicketFilter.APP_FACT_PARAM + "] is missing");
050                }
051
052                return createApplication(applicationClassName);
053        }
054
055        /**
056         * Instantiates the application instance.
057         * 
058         * @param applicationClassName
059         *            the classname of the application to create
060         * @return the web application
061         */
062        protected WebApplication createApplication(final String applicationClassName)
063        {
064                try
065                {
066                        ClassLoader loader = Thread.currentThread().getContextClassLoader();
067                        if (loader == null)
068                        {
069                                loader = getClass().getClassLoader();
070                        }
071
072                        // see http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=6500212
073                        // final Class<?> applicationClass = loader.loadClass(applicationClassName);
074                        final Class<?> applicationClass = Class.forName(applicationClassName, false, loader);
075                        if (WebApplication.class.isAssignableFrom(applicationClass))
076                        {
077                                // Construct WebApplication subclass
078                                return (WebApplication)applicationClass.getDeclaredConstructor().newInstance();
079                        }
080                        else
081                        {
082                                throw new WicketRuntimeException("Application class " + applicationClassName +
083                                        " must be a subclass of WebApplication");
084                        }
085                }
086                catch (ClassNotFoundException | InstantiationException | IllegalAccessException | SecurityException
087                                | NoSuchMethodException | InvocationTargetException e)
088                {
089                        throw new WicketRuntimeException("Unable to create application of class " +
090                                applicationClassName, e);
091                }
092        }
093
094        /** {@inheritDoc} */
095        @Override
096        public void destroy(WicketFilter filter)
097        {
098        }
099
100}