/*
* Copyright 2002-2016 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.multipart.support;
import java.io.IOException;
import javax.servlet.FilterChain;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.springframework.web.context.WebApplicationContext;
import org.springframework.web.context.support.WebApplicationContextUtils;
import org.springframework.web.filter.OncePerRequestFilter;
import org.springframework.web.multipart.MultipartHttpServletRequest;
import org.springframework.web.multipart.MultipartResolver;
/**
* Servlet Filter that resolves multipart requests via a {@link MultipartResolver}.
* in the root web application context.
*
* <p>Looks up the MultipartResolver in Spring's root web application context.
* Supports a "multipartResolverBeanName" filter init-param in {@code web.xml};
* the default bean name is "filterMultipartResolver".
*
* <p>If no MultipartResolver bean is found, this filter falls back to a default
* MultipartResolver: {@link StandardServletMultipartResolver} for Servlet 3.0,
* based on a multipart-config section in {@code web.xml}.
* Note however that at present the Servlet specification only defines how to
* enable multipart configuration on a Servlet and as a result multipart request
* processing is likely not possible in a Filter unless the Servlet container
* provides a workaround such as Tomcat's "allowCasualMultipartParsing" property.
*
* <p>MultipartResolver lookup is customizable: Override this filter's
* {@code lookupMultipartResolver} method to use a custom MultipartResolver
* instance, for example if not using a Spring web application context.
* Note that the lookup method should not create a new MultipartResolver instance
* for each call but rather return a reference to a pre-built instance.
*
* <p>Note: This filter is an <b>alternative</b> to using DispatcherServlet's
* MultipartResolver support, for example for web applications with custom web views
* which do not use Spring's web MVC, or for custom filters applied before a Spring MVC
* DispatcherServlet (e.g. {@link org.springframework.web.filter.HiddenHttpMethodFilter}).
* In any case, this filter should not be combined with servlet-specific multipart resolution.
*
* @author Juergen Hoeller
* @since 08.10.2003
* @see #setMultipartResolverBeanName
* @see #lookupMultipartResolver
* @see org.springframework.web.multipart.MultipartResolver
* @see org.springframework.web.servlet.DispatcherServlet
*/
public class MultipartFilter extends OncePerRequestFilter {
public static final String DEFAULT_MULTIPART_RESOLVER_BEAN_NAME = "filterMultipartResolver";
private final MultipartResolver defaultMultipartResolver = new StandardServletMultipartResolver();
private String multipartResolverBeanName = DEFAULT_MULTIPART_RESOLVER_BEAN_NAME;
/**
* Set the bean name of the MultipartResolver to fetch from Spring's
* root application context. Default is "filterMultipartResolver".
*/
public void setMultipartResolverBeanName(String multipartResolverBeanName) {
this.multipartResolverBeanName = multipartResolverBeanName;
}
/**
* Return the bean name of the MultipartResolver to fetch from Spring's
* root application context.
*/
protected String getMultipartResolverBeanName() {
return this.multipartResolverBeanName;
}
/**
* Check for a multipart request via this filter's MultipartResolver,
* and wrap the original request with a MultipartHttpServletRequest if appropriate.
* <p>All later elements in the filter chain, most importantly servlets, benefit
* from proper parameter extraction in the multipart case, and are able to cast to
* MultipartHttpServletRequest if they need to.
*/
@Override
protected void doFilterInternal(
HttpServletRequest request, HttpServletResponse response, FilterChain filterChain)
throws ServletException, IOException {
MultipartResolver multipartResolver = lookupMultipartResolver(request);
HttpServletRequest processedRequest = request;
if (multipartResolver.isMultipart(processedRequest)) {
if (logger.isDebugEnabled()) {
logger.debug("Resolving multipart request [" + processedRequest.getRequestURI() +
"] with MultipartFilter");
}
processedRequest = multipartResolver.resolveMultipart(processedRequest);
}
else {
// A regular request...
if (logger.isDebugEnabled()) {
logger.debug("Request [" + processedRequest.getRequestURI() + "] is not a multipart request");
}
}
try {
filterChain.doFilter(processedRequest, response);
}
finally {
if (processedRequest instanceof MultipartHttpServletRequest) {
multipartResolver.cleanupMultipart((MultipartHttpServletRequest) processedRequest);
}
}
}
/**
* Look up the MultipartResolver that this filter should use,
* taking the current HTTP request as argument.
* <p>The default implementation delegates to the {@code lookupMultipartResolver}
* without arguments.
* @return the MultipartResolver to use
* @see #lookupMultipartResolver()
*/
protected MultipartResolver lookupMultipartResolver(HttpServletRequest request) {
return lookupMultipartResolver();
}
/**
* Look for a MultipartResolver bean in the root web application context.
* Supports a "multipartResolverBeanName" filter init param; the default
* bean name is "filterMultipartResolver".
* <p>This can be overridden to use a custom MultipartResolver instance,
* for example if not using a Spring web application context.
* @return the MultipartResolver instance, or {@code null} if none found
*/
protected MultipartResolver lookupMultipartResolver() {
WebApplicationContext wac = WebApplicationContextUtils.getWebApplicationContext(getServletContext());
String beanName = getMultipartResolverBeanName();
if (wac != null && wac.containsBean(beanName)) {
if (logger.isDebugEnabled()) {
logger.debug("Using MultipartResolver '" + beanName + "' for MultipartFilter");
}
return wac.getBean(beanName, MultipartResolver.class);
}
else {
return this.defaultMultipartResolver;
}
}
}