/*
* Copyright 2002-2015 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;
/**
* 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 (InternalResourceView.class == viewClass && jstlPresent) {
viewClass = JstlView.class;
}
setViewClass(viewClass);
}
/**
* A convenience constructor that allows for specifying {@link #setPrefix prefix}
* and {@link #setSuffix suffix} as constructor arguments.
* @param prefix the prefix that gets prepended to view names when building a URL
* @param suffix the suffix that gets appended to view names when building a URL
* @since 4.3
*/
public InternalResourceViewResolver(String prefix, String suffix) {
this();
setPrefix(prefix);
setSuffix(suffix);
}
/**
* 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 = alwaysInclude;
}
@Override
protected AbstractUrlBasedView buildView(String viewName) throws Exception {
InternalResourceView view = (InternalResourceView) super.buildView(viewName);
if (this.alwaysInclude != null) {
view.setAlwaysInclude(this.alwaysInclude);
}
view.setPreventDispatchLoop(true);
return view;
}
}