| /** |
| * Copyright (C) 2010 Google, Inc. |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| package com.google.inject.persist; |
| |
| import com.google.inject.Inject; |
| import com.google.inject.Singleton; |
| |
| import java.io.IOException; |
| |
| import javax.servlet.Filter; |
| import javax.servlet.FilterChain; |
| import javax.servlet.FilterConfig; |
| import javax.servlet.ServletException; |
| import javax.servlet.ServletRequest; |
| import javax.servlet.ServletResponse; |
| |
| /** |
| * Apply this filter to enable the HTTP Request unit of work and to have |
| * guice-persist manage the lifecycle of active units of work. |
| * The filter automatically starts and stops the relevant {@link PersistService} |
| * upon {@link javax.servlet.Filter#init(javax.servlet.FilterConfig)} and |
| * {@link javax.servlet.Filter#destroy()} respectively. |
| * |
| * <p> To be able to use the open session-in-view pattern (i.e. work per request), |
| * register this filter <b>once</b> in your Guice {@code ServletModule}. It is |
| * important that you register this filter before any other filter. |
| * |
| * For multiple providers, you should register this filter once per provider, inside |
| * a private module for each persist module installed (this must be the same private |
| * module where the specific persist module is itself installed). |
| * |
| * <p> |
| * Example configuration: |
| * <pre>{@code |
| * public class MyModule extends ServletModule { |
| * public void configureServlets() { |
| * filter("/*").through(PersistFilter.class); |
| * |
| * serve("/index.html").with(MyHtmlServlet.class); |
| * // Etc. |
| * } |
| * } |
| * }</pre> |
| * <p> |
| * This filter is thread safe and allows you to create injectors concurrently |
| * and deploy multiple guice-persist modules within the same injector, or even |
| * multiple injectors with persist modules withing the same JVM or web app. |
| * <p> |
| * This filter requires the Guice Servlet extension. |
| * |
| * @author Dhanji R. Prasanna (dhanji@gmail.com) |
| */ |
| @Singleton |
| public final class PersistFilter implements Filter { |
| private final UnitOfWork unitOfWork; |
| private final PersistService persistService; |
| |
| @Inject |
| public PersistFilter(UnitOfWork unitOfWork, PersistService persistService) { |
| this.unitOfWork = unitOfWork; |
| this.persistService = persistService; |
| } |
| |
| public void init(FilterConfig filterConfig) throws ServletException { |
| persistService.start(); |
| } |
| |
| public void destroy() { |
| persistService.stop(); |
| } |
| |
| public void doFilter(final ServletRequest servletRequest, final ServletResponse servletResponse, |
| final FilterChain filterChain) throws IOException, ServletException { |
| |
| unitOfWork.begin(); |
| try { |
| filterChain.doFilter(servletRequest, servletResponse); |
| } finally { |
| unitOfWork.end(); |
| } |
| } |
| } |