/*
 * 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
 *
 *      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 javax.servlet.http.HttpServletRequest;
import javax.servlet.http.Part;

import org.apache.commons.logging.LogFactory;

import org.springframework.util.StringUtils;
import org.springframework.web.multipart.MultipartException;
import org.springframework.web.multipart.MultipartHttpServletRequest;
import org.springframework.web.multipart.MultipartResolver;

Standard implementation of the MultipartResolver interface, based on the Servlet 3.0 Part API. To be added as "multipartResolver" bean to a Spring DispatcherServlet context, without any extra configuration at the bean level (see below). 
Note: In order to use Servlet 3.0 based multipart parsing, you need to mark the affected servlet with a "multipart-config" section in web.xml, or with a MultipartConfigElement in programmatic servlet registration, or (in case of a custom servlet class) possibly with a MultipartConfig annotation on your servlet class. Configuration settings such as maximum sizes or storage locations need to be applied at that servlet registration level; Servlet 3.0 does not allow for them to be set at the MultipartResolver level. 
public class AppInitializer extends AbstractAnnotationConfigDispatcherServletInitializer {
 // ...
 @Override
 protected void customizeRegistration(ServletRegistration.Dynamic registration) {
    // Optionally also set maxFileSize, maxRequestSize, fileSizeThreshold
    registration.setMultipartConfig(new MultipartConfigElement("/tmp"));
  }
}

Author:
Juergen Hoeller
See Also:
setResolveLazily
HttpServletRequest.getParts()
CommonsMultipartResolver
Since:
3.1/**
 * Standard implementation of the {@link MultipartResolver} interface,
 * based on the Servlet 3.0 {@link javax.servlet.http.Part} API.
 * To be added as "multipartResolver" bean to a Spring DispatcherServlet context,
 * without any extra configuration at the bean level (see below).
 *
 * <p><b>Note:</b> In order to use Servlet 3.0 based multipart parsing,
 * you need to mark the affected servlet with a "multipart-config" section in
 * {@code web.xml}, or with a {@link javax.servlet.MultipartConfigElement}
 * in programmatic servlet registration, or (in case of a custom servlet class)
 * possibly with a {@link javax.servlet.annotation.MultipartConfig} annotation
 * on your servlet class. Configuration settings such as maximum sizes or
 * storage locations need to be applied at that servlet registration level;
 * Servlet 3.0 does not allow for them to be set at the MultipartResolver level.
 *
 * <pre class="code">
 * public class AppInitializer extends AbstractAnnotationConfigDispatcherServletInitializer {
 *	 // ...
 *	 &#064;Override
 *	 protected void customizeRegistration(ServletRegistration.Dynamic registration) {
 *     // Optionally also set maxFileSize, maxRequestSize, fileSizeThreshold
 *     registration.setMultipartConfig(new MultipartConfigElement("/tmp"));
 *   }
 * }
 * </pre>
 *
 * @author Juergen Hoeller
 * @since 3.1
 * @see #setResolveLazily
 * @see HttpServletRequest#getParts()
 * @see org.springframework.web.multipart.commons.CommonsMultipartResolver
 */
public class StandardServletMultipartResolver implements MultipartResolver {

	private boolean resolveLazily = false;


	
Set whether to resolve the multipart request lazily at the time of
file or parameter access.
Default is "false", resolving the multipart elements immediately, throwing corresponding exceptions at the time of the resolveMultipart call. Switch this to "true" for lazy multipart parsing, throwing parse exceptions once the application attempts to obtain multipart files or parameters. 
Since:
3.2.9/**
	 * Set whether to resolve the multipart request lazily at the time of
	 * file or parameter access.
	 * <p>Default is "false", resolving the multipart elements immediately, throwing
	 * corresponding exceptions at the time of the {@link #resolveMultipart} call.
	 * Switch this to "true" for lazy multipart parsing, throwing parse exceptions
	 * once the application attempts to obtain multipart files or parameters.
	 * @since 3.2.9
	 */
	public void setResolveLazily(boolean resolveLazily) {
		this.resolveLazily = resolveLazily;
	}


	@Override
	public boolean isMultipart(HttpServletRequest request) {
		return StringUtils.startsWithIgnoreCase(request.getContentType(), "multipart/");
	}

	@Override
	public MultipartHttpServletRequest resolveMultipart(HttpServletRequest request) throws MultipartException {
		return new StandardMultipartHttpServletRequest(request, this.resolveLazily);
	}

	@Override
	public void cleanupMultipart(MultipartHttpServletRequest request) {
		if (!(request instanceof AbstractMultipartHttpServletRequest) ||
				((AbstractMultipartHttpServletRequest) request).isResolved()) {
			// To be on the safe side: explicitly delete the parts,
			// but only actual file parts (for Resin compatibility)
			try {
				for (Part part : request.getParts()) {
					if (request.getFile(part.getName()) != null) {
						part.delete();
					}
				}
			}
			catch (Throwable ex) {
				LogFactory.getLog(getClass()).warn("Failed to perform cleanup of multipart items", ex);
			}
		}
	}

}