/*
* 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.resource;
import java.io.IOException;
import javax.servlet.RequestDispatcher;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.springframework.util.StringUtils;
import org.springframework.web.HttpRequestHandler;
import org.springframework.web.context.ServletContextAware;
/**
* An {@link HttpRequestHandler} for serving static files using the Servlet container's "default" Servlet.
*
* <p>This handler is intended to be used with a "/*" mapping when the
* {@link org.springframework.web.servlet.DispatcherServlet DispatcherServlet}
* is mapped to "/", thus overriding the Servlet container's default handling of static resources.
* The mapping to this handler should generally be ordered as the last in the chain so that it will
* only execute when no other more specific mappings (i.e., to controllers) can be matched.
*
* <p>Requests are handled by forwarding through the {@link RequestDispatcher} obtained via the
* name specified through the {@link #setDefaultServletName "defaultServletName" property}.
* In most cases, the {@code defaultServletName} does not need to be set explicitly, as the
* handler checks at initialization time for the presence of the default Servlet of well-known
* containers such as Tomcat, Jetty, Resin, WebLogic and WebSphere. However, when running in a
* container where the default Servlet's name is not known, or where it has been customized
* via server configuration, the {@code defaultServletName} will need to be set explicitly.
*
* @author Jeremy Grelle
* @author Juergen Hoeller
* @since 3.0.4
*/
public class DefaultServletHttpRequestHandler implements HttpRequestHandler, ServletContextAware {
/** Default Servlet name used by Tomcat, Jetty, JBoss, and GlassFish */
private static final String COMMON_DEFAULT_SERVLET_NAME = "default";
/** Default Servlet name used by Google App Engine */
private static final String GAE_DEFAULT_SERVLET_NAME = "_ah_default";
/** Default Servlet name used by Resin */
private static final String RESIN_DEFAULT_SERVLET_NAME = "resin-file";
/** Default Servlet name used by WebLogic */
private static final String WEBLOGIC_DEFAULT_SERVLET_NAME = "FileServlet";
/** Default Servlet name used by WebSphere */
private static final String WEBSPHERE_DEFAULT_SERVLET_NAME = "SimpleFileServlet";
private String defaultServletName;
private ServletContext servletContext;
/**
* Set the name of the default Servlet to be forwarded to for static resource requests.
*/
public void setDefaultServletName(String defaultServletName) {
this.defaultServletName = defaultServletName;
}
/**
* If the {@code defaultServletName} property has not been explicitly set,
* attempts to locate the default Servlet using the known common
* container-specific names.
*/
@Override
public void setServletContext(ServletContext servletContext) {
this.servletContext = servletContext;
if (!StringUtils.hasText(this.defaultServletName)) {
if (this.servletContext.getNamedDispatcher(COMMON_DEFAULT_SERVLET_NAME) != null) {
this.defaultServletName = COMMON_DEFAULT_SERVLET_NAME;
}
else if (this.servletContext.getNamedDispatcher(GAE_DEFAULT_SERVLET_NAME) != null) {
this.defaultServletName = GAE_DEFAULT_SERVLET_NAME;
}
else if (this.servletContext.getNamedDispatcher(RESIN_DEFAULT_SERVLET_NAME) != null) {
this.defaultServletName = RESIN_DEFAULT_SERVLET_NAME;
}
else if (this.servletContext.getNamedDispatcher(WEBLOGIC_DEFAULT_SERVLET_NAME) != null) {
this.defaultServletName = WEBLOGIC_DEFAULT_SERVLET_NAME;
}
else if (this.servletContext.getNamedDispatcher(WEBSPHERE_DEFAULT_SERVLET_NAME) != null) {
this.defaultServletName = WEBSPHERE_DEFAULT_SERVLET_NAME;
}
else {
throw new IllegalStateException("Unable to locate the default servlet for serving static content. " +
"Please set the 'defaultServletName' property explicitly.");
}
}
}
@Override
public void handleRequest(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
RequestDispatcher rd = this.servletContext.getNamedDispatcher(this.defaultServletName);
if (rd == null) {
throw new IllegalStateException("A RequestDispatcher could not be located for the default servlet '" +
this.defaultServletName + "'");
}
rd.forward(request, response);
}
}