/*
* Copyright 2002-2018 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
*
* https://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.lang.Nullable;
import org.springframework.util.Assert;
import org.springframework.util.StringUtils;
import org.springframework.web.HttpRequestHandler;
import org.springframework.web.context.ServletContextAware;
An HttpRequestHandler for serving static files using the Servlet container's "default" Servlet. This handler is intended to be used with a "/*" mapping when the 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.
Requests are handled by forwarding through the RequestDispatcher obtained via the name specified through the "defaultServletName" property. In most cases, the 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 defaultServletName will need to be set explicitly.
Author: Jeremy Grelle, Juergen Hoeller Since: 3.0.4
/**
* 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. /** 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. /** Default Servlet name used by Google App Engine. */
private static final String GAE_DEFAULT_SERVLET_NAME = "_ah_default";
Default Servlet name used by Resin. /** Default Servlet name used by Resin. */
private static final String RESIN_DEFAULT_SERVLET_NAME = "resin-file";
Default Servlet name used by WebLogic. /** Default Servlet name used by WebLogic. */
private static final String WEBLOGIC_DEFAULT_SERVLET_NAME = "FileServlet";
Default Servlet name used by WebSphere. /** Default Servlet name used by WebSphere. */
private static final String WEBSPHERE_DEFAULT_SERVLET_NAME = "SimpleFileServlet";
@Nullable
private String defaultServletName;
@Nullable
private ServletContext servletContext;
Set the name of the default Servlet to be forwarded to for static resource requests.
/**
* 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 defaultServletName property has not been explicitly set, attempts to locate the default Servlet using the known common container-specific names. /**
* 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 {
Assert.state(this.servletContext != null, "No ServletContext set");
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);
}
}