/*
* Copyright 2002-2009 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 org.springframework.util.ClassUtils;
/**
* Convenient subclass of {@link UrlBasedViewResolver} that supports
* {@link InternalResourceView} (i.e. Servlets and JSPs) and subclasses
* such as {@link JstlView}.
*
* <p>The view class for all views generated by this resolver can be specified
* via {@link #setViewClass}. See {@link UrlBasedViewResolver}'s javadoc for details.
* The default is {@link InternalResourceView}, or {@link JstlView} if the
* JSTL API is present.
*
* <p>BTW, it's good practice to put JSP files that just serve as views under
* WEB-INF, to hide them from direct access (e.g. via a manually entered URL).
* Only controllers will be able to access them then.
*
* <p><b>Note:</b> When chaining ViewResolvers, an InternalResourceViewResolver
* always needs to be last, as it will attempt to resolve any view name,
* no matter whether the underlying resource actually exists.
*
* @author Juergen Hoeller
* @since 17.02.2003
* @see #setViewClass
* @see #setPrefix
* @see #setSuffix
* @see #setRequestContextAttribute
* @see InternalResourceView
* @see JstlView
*/
public class InternalResourceViewResolver extends UrlBasedViewResolver {
private static final boolean jstlPresent = ClassUtils.isPresent(
"javax.servlet.jsp.jstl.core.Config", InternalResourceViewResolver.class.getClassLoader());
private Boolean alwaysInclude;
private Boolean exposeContextBeansAsAttributes;
private String[] exposedContextBeanNames;
/**
* Sets the default {@link #setViewClass view class} to {@link #requiredViewClass}:
* by default {@link InternalResourceView}, or {@link JstlView} if the JSTL API
* is present.
*/
public InternalResourceViewResolver() {
Class viewClass = requiredViewClass();
if (viewClass.equals(InternalResourceView.class) && jstlPresent) {
viewClass = JstlView.class;
}
setViewClass(viewClass);
}
/**
* This resolver requires {@link InternalResourceView}.
*/
@Override
protected Class requiredViewClass() {
return InternalResourceView.class;
}
/**
* Specify whether to always include the view rather than forward to it.
* <p>Default is "false". Switch this flag on to enforce the use of a
* Servlet include, even if a forward would be possible.
* @see InternalResourceView#setAlwaysInclude
*/
public void setAlwaysInclude(boolean alwaysInclude) {
this.alwaysInclude = Boolean.valueOf(alwaysInclude);
}
/**
* Set whether to make all Spring beans in the application context accessible
* as request attributes, through lazy checking once an attribute gets accessed.
* <p>This will make all such beans accessible in plain <code>${...}</code>
* expressions in a JSP 2.0 page, as well as in JSTL's <code>c:out</code>
* value expressions.
* <p>Default is "false".
* @see InternalResourceView#setExposeContextBeansAsAttributes
*/
public void setExposeContextBeansAsAttributes(boolean exposeContextBeansAsAttributes) {
this.exposeContextBeansAsAttributes = exposeContextBeansAsAttributes;
}
/**
* Specify the names of beans in the context which are supposed to be exposed.
* If this is non-null, only the specified beans are eligible for exposure as
* attributes.
* @see InternalResourceView#setExposedContextBeanNames
*/
public void setExposedContextBeanNames(String[] exposedContextBeanNames) {
this.exposedContextBeanNames = exposedContextBeanNames;
}
@Override
protected AbstractUrlBasedView buildView(String viewName) throws Exception {
InternalResourceView view = (InternalResourceView) super.buildView(viewName);
if (this.alwaysInclude != null) {
view.setAlwaysInclude(this.alwaysInclude);
}
if (this.exposeContextBeansAsAttributes != null) {
view.setExposeContextBeansAsAttributes(this.exposeContextBeansAsAttributes);
}
if (this.exposedContextBeanNames != null) {
view.setExposedContextBeanNames(this.exposedContextBeanNames);
}
view.setPreventDispatchLoop(true);
return view;
}
}
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