/*
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* Copyright 2014 gitblit.com.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package com.gitblit.guice;
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import javax.servlet.ServletContext;
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import javax.servlet.ServletContextEvent;
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import org.slf4j.Logger;
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import org.slf4j.LoggerFactory;
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import com.gitblit.servlet.InjectionContextListener;
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import com.google.inject.AbstractModule;
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import com.google.inject.Guice;
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import com.google.inject.Injector;
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/**
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* Guice servlet context listener is a context listener that uses Guice to
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* instantiate and inject servlets, filters, and anything else you might want.
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*
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* @author James Moger
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*
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*/
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public abstract class GuiceContext extends InjectionContextListener {
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public static final String INJECTOR_NAME = Injector.class.getName();
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protected final Logger logger = LoggerFactory.getLogger(getClass());
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protected abstract AbstractModule [] getModules();
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protected abstract void destroyContext(ServletContext context);
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protected Injector getInjector(ServletContext context) {
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Object o = context.getAttribute(INJECTOR_NAME);
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if (o == null) {
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logger.debug("instantiating Guice modules");
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AbstractModule [] modules = getModules();
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logger.debug("getting Guice injector");
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try {
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o = Guice.createInjector(modules);
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logger.debug("setting Guice injector into {} attribute", INJECTOR_NAME);
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context.setAttribute(INJECTOR_NAME, o);
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} catch (Throwable t) {
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logger.error("an error occurred creating the Guice injector", t);
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}
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}
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return (Injector) o;
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}
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/**
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* Instantiates an object.
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*
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* @param clazz
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* @return the object
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*/
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@Override
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protected <X> X instantiate(ServletContext context, Class<X> clazz) {
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try {
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Injector injector = getInjector(context);
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return injector.getInstance(clazz);
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} catch (Throwable t) {
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logger.error(null, t);
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}
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return null;
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}
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@Override
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public final void contextDestroyed(ServletContextEvent contextEvent) {
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ServletContext context = contextEvent.getServletContext();
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context.removeAttribute(INJECTOR_NAME);
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destroyContext(context);
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}
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}
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