/*
* Copyright 2002-2008 the original author or authors.
*
* 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 org.springframework.web.servlet.view;
import javax.servlet.ServletContext;
import javax.servlet.http.HttpServletRequest;
import org.springframework.context.MessageSource;
import org.springframework.web.servlet.support.JstlUtils;
import org.springframework.web.servlet.support.RequestContext;
/**
* Specialization of {@link InternalResourceView} for JSTL pages,
* i.e. JSP pages that use the JSP Standard Tag Library.
*
* <p>Exposes JSTL-specific request attributes specifying locale
* and resource bundle for JSTL's formatting and message tags,
* using Spring's locale and {@link org.springframework.context.MessageSource}.
*
* <p>Typical usage with {@link InternalResourceViewResolver} would look as follows,
* from the perspective of the DispatcherServlet context definition:
*
* <pre class="code">
* <bean id="viewResolver" class="org.springframework.web.servlet.view.InternalResourceViewResolver">
* <property name="viewClass" value="org.springframework.web.servlet.view.JstlView"/>
* <property name="prefix" value="/WEB-INF/jsp/"/>
* <property name="suffix" value=".jsp"/>
* </bean>
*
* <bean id="messageSource" class="org.springframework.context.support.ResourceBundleMessageSource">
* <property name="basename" value="messages"/>
* </bean></pre>
*
* Every view name returned from a handler will be translated to a JSP
* resource (for example: "myView" -> "/WEB-INF/jsp/myView.jsp"), using
* this view class to enable explicit JSTL support.
*
* <p>The specified MessageSource loads messages from "messages.properties" etc
* files in the class path. This will automatically be exposed to views as
* JSTL localization context, which the JSTL fmt tags (message etc) will use.
* Consider using Spring's ReloadableResourceBundleMessageSource instead of
* the standard ResourceBundleMessageSource for more sophistication.
* Of course, any other Spring components can share the same MessageSource.
*
* <p>This is a separate class mainly to avoid JSTL dependencies in
* {@link InternalResourceView} itself. JSTL has not been part of standard
* J2EE up until J2EE 1.4, so we can't assume the JSTL API jar to be
* available on the class path.
*
* <p>Hint: Set the {@link #setExposeContextBeansAsAttributes} flag to "true"
* in order to make all Spring beans in the application context accessible
* within JSTL expressions (e.g. in a <code>c:out</code> value expression).
* This will also make all such beans accessible in plain <code>${...}</code>
* expressions in a JSP 2.0 page.
*
* @author Juergen Hoeller
* @since 27.02.2003
* @see org.springframework.web.servlet.support.JstlUtils#exposeLocalizationContext
* @see InternalResourceViewResolver
* @see org.springframework.context.support.ResourceBundleMessageSource
* @see org.springframework.context.support.ReloadableResourceBundleMessageSource
*/
public class JstlView extends InternalResourceView {
private MessageSource messageSource;
/**
* Constructor for use as a bean.
* @see #setUrl
*/
public JstlView() {
}
/**
* Create a new JstlView with the given URL.
* @param url the URL to forward to
*/
public JstlView(String url) {
super(url);
}
/**
* Create a new JstlView with the given URL.
* @param url the URL to forward to
* @param messageSource the MessageSource to expose to JSTL tags
* (will be wrapped with a JSTL-aware MessageSource that is aware of JSTL's
* <code>javax.servlet.jsp.jstl.fmt.localizationContext</code> context-param)
* @see JstlUtils#getJstlAwareMessageSource
*/
public JstlView(String url, MessageSource messageSource) {
this(url);
this.messageSource = messageSource;
}
/**
* Wraps the MessageSource with a JSTL-aware MessageSource that is aware
* of JSTL's <code>javax.servlet.jsp.jstl.fmt.localizationContext</code>
* context-param.
* @see JstlUtils#getJstlAwareMessageSource
*/
protected void initServletContext(ServletContext servletContext) {
if (this.messageSource != null) {
this.messageSource = JstlUtils.getJstlAwareMessageSource(servletContext, this.messageSource);
}
super.initServletContext(servletContext);
}
/**
* Exposes a JSTL LocalizationContext for Spring's locale and MessageSource.
* @see JstlUtils#exposeLocalizationContext
*/
protected void exposeHelpers(HttpServletRequest request) throws Exception {
if (this.messageSource != null) {
JstlUtils.exposeLocalizationContext(request, this.messageSource);
}
else {
JstlUtils.exposeLocalizationContext(new RequestContext(request, getServletContext()));
}
}
}