Spring Framework example source code file (ServletForwardingController.java)

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Java - Spring Framework tags/keywords

abstractcontroller, beannameaware, forwarded, http, httpservletresponse, httpservletresponse, modelandview, no, request, requestdispatcher, response, servlet, servletexception, servletexception, servletforwardingcontroller, servletforwardingcontroller, string, string

The Spring Framework ServletForwardingController.java source code

/*
 * Copyright 2002-2007 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.mvc;

import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.springframework.beans.factory.BeanNameAware;
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.
 *
 * <p>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.
 *
 * <p>Example: web.xml, mapping all "/myservlet" requests to a Spring dispatcher.
 * Also defines a custom "myServlet", but <i>without servlet mapping.
 *
 * <pre>
 * <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></pre>
 *
 * <b>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.
 *
 * <pre>
 * <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></pre>
 *
 * @author Juergen Hoeller
 * @since 1.1.1
 * @see ServletWrappingController
 * @see org.springframework.orm.hibernate3.support.OpenSessionInViewInterceptor
 * @see org.springframework.orm.hibernate3.support.OpenSessionInViewFilter
 * @see org.springframework.orm.jdo.support.OpenPersistenceManagerInViewInterceptor
 * @see org.springframework.orm.jdo.support.OpenPersistenceManagerInViewFilter
 */
public class ServletForwardingController extends AbstractController implements BeanNameAware {

	private String servletName;

	private String beanName;
	

	/**
	 * Set the name of the servlet to forward to,
	 * i.e. the "servlet-name" of the target servlet in web.xml.
	 * <p>Default is the bean name of this controller.
	 */
	public void setServletName(String servletName) {
		this.servletName = servletName;
	}

	public void setBeanName(String name) {
		this.beanName = name;
		if (this.servletName == null) {
			this.servletName = name;
		}
	}


	protected ModelAndView handleRequestInternal(HttpServletRequest request, HttpServletResponse response)
			throws Exception {

		RequestDispatcher rd = getServletContext().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.isDebugEnabled()) {
				logger.debug("Included servlet [" + this.servletName +
						"] in ServletForwardingController '" + this.beanName + "'");
			}
		}
		else {
			rd.forward(request, response);
			if (logger.isDebugEnabled()) {
				logger.debug("Forwarded to servlet [" + this.servletName +
						"] in ServletForwardingController '" + this.beanName + "'");
			}
		}
		return null;
	}

	/**
	 * Determine whether to use RequestDispatcher's <code>include or
	 * <code>forward method.
	 * <p>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, 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());
	}

}