org.springframework.web.servlet.mvc.ServletForwardingController Maven / Gradle / Ivy
/*
* Copyright 2002-2017 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.mvc;
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.beans.factory.BeanNameAware;
import org.springframework.lang.Nullable;
import org.springframework.util.Assert;
import org.springframework.web.servlet.ModelAndView;
import org.springframework.web.util.WebUtils;
/**
* Spring Controller implementation that forwards to a named servlet,
* i.e. the "servlet-name" in web.xml rather than a URL path mapping.
* A target servlet doesn't even need a "servlet-mapping" in web.xml
* in the first place: A "servlet" declaration is sufficient.
*
* Useful to invoke an existing servlet via Spring's dispatching infrastructure,
* for example to apply Spring HandlerInterceptors to its requests. This will work
* even in a minimal Servlet container that does not support Servlet filters.
*
*
Example: web.xml, mapping all "/myservlet" requests to a Spring dispatcher.
* Also defines a custom "myServlet", but without servlet mapping.
*
*
* <servlet>
* <servlet-name>myServlet</servlet-name>
* <servlet-class>mypackage.TestServlet</servlet-class>
* </servlet>
*
* <servlet>
* <servlet-name>myDispatcher</servlet-name>
* <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
* </servlet>
*
* <servlet-mapping>
* <servlet-name>myDispatcher</servlet-name>
* <url-pattern>/myservlet</url-pattern>
* </servlet-mapping>
*
* Example: myDispatcher-servlet.xml, in turn forwarding "/myservlet" to your
* servlet (identified by servlet name). All such requests will go through the
* configured HandlerInterceptor chain (e.g. an OpenSessionInViewInterceptor).
* From the servlet point of view, everything will work as usual.
*
*
* <bean id="urlMapping" class="org.springframework.web.servlet.handler.SimpleUrlHandlerMapping">
* <property name="interceptors">
* <list>
* <ref bean="openSessionInViewInterceptor"/>
* </list>
* </property>
* <property name="mappings">
* <props>
* <prop key="/myservlet">myServletForwardingController</prop>
* </props>
* </property>
* </bean>
*
* <bean id="myServletForwardingController" class="org.springframework.web.servlet.mvc.ServletForwardingController">
* <property name="servletName"><value>myServlet</value></property>
* </bean>
*
* @author Juergen Hoeller
* @since 1.1.1
* @see ServletWrappingController
* @see org.springframework.orm.jpa.support.OpenEntityManagerInViewInterceptor
* @see org.springframework.orm.jpa.support.OpenEntityManagerInViewFilter
*/
public class ServletForwardingController extends AbstractController implements BeanNameAware {
@Nullable
private String servletName;
@Nullable
private String beanName;
public ServletForwardingController() {
super(false);
}
/**
* Set the name of the servlet to forward to,
* i.e. the "servlet-name" of the target servlet in web.xml.
* Default is the bean name of this controller.
*/
public void setServletName(String servletName) {
this.servletName = servletName;
}
@Override
public void setBeanName(String name) {
this.beanName = name;
if (this.servletName == null) {
this.servletName = name;
}
}
@Override
protected ModelAndView handleRequestInternal(HttpServletRequest request, HttpServletResponse response)
throws Exception {
ServletContext servletContext = getServletContext();
Assert.state(servletContext != null, "No ServletContext");
RequestDispatcher rd = servletContext.getNamedDispatcher(this.servletName);
if (rd == null) {
throw new ServletException("No servlet with name '" + this.servletName + "' defined in web.xml");
}
// If already included, include again, else forward.
if (useInclude(request, response)) {
rd.include(request, response);
if (logger.isTraceEnabled()) {
logger.trace("Included servlet [" + this.servletName +
"] in ServletForwardingController '" + this.beanName + "'");
}
}
else {
rd.forward(request, response);
if (logger.isTraceEnabled()) {
logger.trace("Forwarded to servlet [" + this.servletName +
"] in ServletForwardingController '" + this.beanName + "'");
}
}
return null;
}
/**
* Determine whether to use RequestDispatcher's {@code include} or
* {@code forward} method.
*
Performs a check whether an include URI attribute is found in the request,
* indicating an include request, and whether the response has already been committed.
* In both cases, an include will be performed, as a forward is not possible anymore.
* @param request current HTTP request
* @param response current HTTP response
* @return {@code true} for include, {@code false} for forward
* @see javax.servlet.RequestDispatcher#forward
* @see javax.servlet.RequestDispatcher#include
* @see javax.servlet.ServletResponse#isCommitted
* @see org.springframework.web.util.WebUtils#isIncludeRequest
*/
protected boolean useInclude(HttpServletRequest request, HttpServletResponse response) {
return (WebUtils.isIncludeRequest(request) || response.isCommitted());
}
}