Java tutorial
/* * Copyright (c) 2010 The original author(s) * * 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.github.peholmst.springsecuritydemo.servlet; import java.io.IOException; import java.util.Locale; import javax.servlet.ServletConfig; import javax.servlet.ServletException; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletRequestWrapper; import javax.servlet.http.HttpServletResponse; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import org.springframework.beans.factory.NoSuchBeanDefinitionException; import org.springframework.context.ApplicationContext; import org.springframework.context.i18n.LocaleContextHolder; import org.springframework.web.context.WebApplicationContext; import org.springframework.web.context.request.RequestContextHolder; import org.springframework.web.context.request.ServletRequestAttributes; import org.springframework.web.context.support.WebApplicationContextUtils; import org.springframework.web.servlet.DispatcherServlet; import org.springframework.web.servlet.LocaleResolver; import org.springframework.web.servlet.i18n.SessionLocaleResolver; import com.vaadin.Application; import com.vaadin.terminal.gwt.server.AbstractApplicationServlet; /** * This Vaadin application servlet looks up the {@link Application} instance * from the {@link WebApplicationContext} returned by * {@link WebApplicationContextUtils#getWebApplicationContext(javax.servlet.ServletContext)} * . The name of the application bean has to be defined as a servlet parameter * named <code>applicationBean</code>. In addition, the application bean has to * have either prototype or session scope, otherwise all users will share the * same application instance (not good). * <p> * This servlet also resolves the locale using a Spring locale resolver and * updates the requests accordingly. * <p> * This class is based on the <a * href="http://dev.vaadin.com/browser/incubator/SpringApplication" * >SpringApplication example</a> by Petri Hakala, with some minor modifications * here and there by yours truly. * * @author Petter Holmstrm */ public class SpringApplicationServlet extends AbstractApplicationServlet { private static final long serialVersionUID = 9119643883315827366L; /** * Protected Apache Commons Log for logging stuff. */ protected transient final Log logger = LogFactory.getLog(getClass()); private transient WebApplicationContext applicationContext; private Class<? extends Application> applicationClass; private String applicationBean; private transient LocaleResolver localeResolver; @SuppressWarnings("unchecked") @Override public void init(ServletConfig servletConfig) throws ServletException { super.init(servletConfig); /* * Look up the name of the Vaadin application bean. The bean should be * either a prototype or have session scope. */ applicationBean = servletConfig.getInitParameter("applicationBean"); if (applicationBean == null) { if (logger.isErrorEnabled()) { logger.error("ApplicationBean not specified in servlet parameters"); } throw new ServletException("ApplicationBean not specified in servlet parameters"); } if (logger.isInfoEnabled()) { logger.info("Using applicationBean '" + applicationBean + "'"); } /* * Fetch the Spring web application context */ applicationContext = WebApplicationContextUtils.getWebApplicationContext(servletConfig.getServletContext()); if (applicationContext.isSingleton(applicationBean)) { if (logger.isErrorEnabled()) { logger.error("ApplicationBean must not be a singleton"); } throw new ServletException("ApplicationBean must not be a singleton"); } if (!applicationContext.isPrototype(applicationBean) && logger.isWarnEnabled()) { logger.warn("ApplicationBean is not a prototype"); } /* * Get the application class from the application context */ applicationClass = (Class<? extends Application>) applicationContext.getType(applicationBean); if (logger.isDebugEnabled()) { logger.debug("Vaadin application class is [" + applicationClass + "]"); } /* * Initialize the locale resolver */ initLocaleResolver(applicationContext); } private void initLocaleResolver(ApplicationContext context) { try { /* * Try to look up the locale resolver from the application context */ localeResolver = context.getBean(DispatcherServlet.LOCALE_RESOLVER_BEAN_NAME, LocaleResolver.class); if (logger.isInfoEnabled()) { logger.info("Using LocaleResolver [" + localeResolver + "]"); } } catch (NoSuchBeanDefinitionException e) { /* * No locale resolver was defined in the application context, so we * create a default one. */ localeResolver = new SessionLocaleResolver(); if (logger.isWarnEnabled()) { logger.warn( "Unable to locate LocaleResolver with name '" + DispatcherServlet.LOCALE_RESOLVER_BEAN_NAME + "', using default [" + localeResolver + "]"); } } } @Override protected void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { /* * Resolve the locale from the request */ final Locale locale = localeResolver.resolveLocale(request); if (logger.isDebugEnabled()) { logger.debug("Resolved locale [" + locale + "]"); } /* * Store the locale in the LocaleContextHolder, making it available to * Spring. */ LocaleContextHolder.setLocale(locale); ServletRequestAttributes requestAttributes = new ServletRequestAttributes(request); RequestContextHolder.setRequestAttributes(requestAttributes); try { /* * We need to override the request to return the locale resolved by * Spring. */ super.service(new HttpServletRequestWrapper(request) { @Override public Locale getLocale() { return locale; } }, response); } finally { if (!locale.equals(LocaleContextHolder.getLocale())) { /* * The locale in LocaleContextHolder was changed during the * request, so we have to update the resolver. */ if (logger.isDebugEnabled()) { logger.debug("Locale changed, updating locale resolver"); } localeResolver.setLocale(request, response, LocaleContextHolder.getLocale()); } LocaleContextHolder.resetLocaleContext(); RequestContextHolder.resetRequestAttributes(); } } @Override protected Class<? extends Application> getApplicationClass() throws ClassNotFoundException { return applicationClass; } @Override protected Application getNewApplication(HttpServletRequest request) throws ServletException { /* * AS the application bean should be defined either as a prototype or a * sessions scoped bean, this call should always return a new * application instance. */ return (Application) applicationContext.getBean(applicationBean); } }