dispatcherservlet.java

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/*
 * 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;

import java.io.IOException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Enumeration;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Locale;
import java.util.Map;
import java.util.Properties;
import java.util.Set;

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

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import org.springframework.beans.BeansException;
import org.springframework.beans.factory.BeanFactoryUtils;
import org.springframework.beans.factory.BeanInitializationException;
import org.springframework.beans.factory.NoSuchBeanDefinitionException;
import org.springframework.beans.factory.config.AutowireCapableBeanFactory;
import org.springframework.context.ApplicationContext;
import org.springframework.context.i18n.LocaleContext;
import org.springframework.context.i18n.LocaleContextHolder;
import org.springframework.core.OrderComparator;
import org.springframework.core.io.ClassPathResource;
import org.springframework.core.io.support.PropertiesLoaderUtils;
import org.springframework.ui.context.ThemeSource;
import org.springframework.util.ClassUtils;
import org.springframework.util.StringUtils;
import org.springframework.web.context.request.RequestAttributes;
import org.springframework.web.context.request.RequestContextHolder;
import org.springframework.web.context.request.ServletRequestAttributes;
import org.springframework.web.multipart.MultipartException;
import org.springframework.web.multipart.MultipartHttpServletRequest;
import org.springframework.web.multipart.MultipartResolver;
import org.springframework.web.util.NestedServletException;
import org.springframework.web.util.UrlPathHelper;
import org.springframework.web.util.WebUtils;

/**
 * Central dispatcher for HTTP request handlers/controllers,
 * e.g. for web UI controllers or HTTP-based remote service exporters.
 * Dispatches to registered handlers for processing a web request,
 * providing convenient mapping and exception handling facilities.
 *
 * <p>This servlet is very flexible: It can be used with just about any workflow,
 * with the installation of the appropriate adapter classes. It offers the
 * following functionality that distinguishes it from other request-driven
 * web MVC frameworks:
 *
 * <ul>
 * <li>It is based around a JavaBeans configuration mechanism.
 *
 * <li>It can use any {@link HandlerMapping} implementation - pre-built or provided
 * as part of an application - to control the routing of requests to handler objects.
 * Default is {@link org.springframework.web.servlet.handler.BeanNameUrlHandlerMapping}.
 * HandlerMapping objects can be defined as beans in the servlet's application context,
 * implementing the HandlerMapping interface, overriding the default HandlerMapping
 * if present. HandlerMappings can be given any bean name (they are tested by type).
 *
 * <li>It can use any {@link HandlerAdapter}; this allows to use any handler interface.
 * Default adapters are {@link org.springframework.web.servlet.mvc.HttpRequestHandlerAdapter},
 * {@link org.springframework.web.servlet.mvc.SimpleControllerHandlerAdapter} and
 * {@link org.springframework.web.servlet.mvc.throwaway.ThrowawayControllerHandlerAdapter},
 * for Spring's {@link org.springframework.web.HttpRequestHandler},
 * {@link org.springframework.web.servlet.mvc.Controller} and
 * {@link org.springframework.web.servlet.mvc.throwaway.ThrowawayController} interfaces,
 * respectively. HandlerAdapter objects can be added as beans in the application context,
 * overriding the default HandlerAdapters. Like HandlerMappings, HandlerAdapters
 * can be given any bean name (they are tested by type).
 *
 * <li>The dispatcher's exception resolution strategy can be specified via a
 * {@link HandlerExceptionResolver}, for example mapping certain exceptions to
 * error pages. Default is none. Additional HandlerExceptionResolvers can be added
 * through the application context. HandlerExceptionResolver can be given any
 * bean name (they are tested by type).
 *
 * <li>Its view resolution strategy can be specified via a {@link ViewResolver}
 * implementation, resolving symbolic view names into View objects. Default is
 * {@link org.springframework.web.servlet.view.InternalResourceViewResolver}.
 * ViewResolver objects can be added as beans in the application context,
 * overriding the default ViewResolver. ViewResolvers can be given any bean name
 * (they are tested by type).
 *
 * <li>If a {@link View} or view name is not supplied by the user, then the configured
 * {@link RequestToViewNameTranslator} will translate the current request into a
 * view name. The corresponding bean name is "viewNameTranslator"; the default is
 * {@link org.springframework.web.servlet.view.DefaultRequestToViewNameTranslator}.
 *
 * <li>The dispatcher's strategy for resolving multipart requests is determined by
 * a {@link org.springframework.web.multipart.MultipartResolver} implementation.
 * Implementations for Jakarta Commons FileUpload and Jason Hunter's COS are
 * included; the typical choise is
 * {@link org.springframework.web.multipart.commons.CommonsMultipartResolver}.
 * The MultipartResolver bean name is "multipartResolver"; default is none.
 *
 * <li>Its locale resolution strategy is determined by a {@link LocaleResolver}.
 * Out-of-the-box implementations work via HTTP accept header, cookie, or session.
 * The LocaleResolver bean name is "localeResolver"; default is
 * {@link org.springframework.web.servlet.i18n.AcceptHeaderLocaleResolver}.
 *
 * <li>Its theme resolution strategy is determined by a {@link ThemeResolver}.
 * Implementations for a fixed theme and for cookie and session storage are included.
 * The ThemeResolver bean name is "themeResolver"; default is
 * {@link org.springframework.web.servlet.theme.FixedThemeResolver}.
 * </ul>
 *
 * <p><b>A web application can define any number of DispatcherServlets.</b>
 * Each servlet will operate in its own namespace, loading its own application
 * context with mappings, handlers, etc. Only the root application context
 * as loaded by {@link org.springframework.web.context.ContextLoaderListener},
 * if any, will be shared.
 *
 * @author Rod Johnson
 * @author Juergen Hoeller
 * @author Rob Harrop
 * @see org.springframework.web.HttpRequestHandler
 * @see org.springframework.web.servlet.mvc.Controller
 * @see org.springframework.web.context.ContextLoaderListener
 */
public class DispatcherServlet extends FrameworkServlet {

	/**
	 * Well-known name for the MultipartResolver object in the bean factory for this namespace.
	 */
	public static final String MULTIPART_RESOLVER_BEAN_NAME = "multipartResolver";

	/**
	 * Well-known name for the LocaleResolver object in the bean factory for this namespace.
	 */
	public static final String LOCALE_RESOLVER_BEAN_NAME = "localeResolver";

	/**
	 * Well-known name for the ThemeResolver object in the bean factory for this namespace.
	 */
	public static final String THEME_RESOLVER_BEAN_NAME = "themeResolver";

	/**
	 * Well-known name for the HandlerMapping object in the bean factory for this namespace.
	 * Only used when "detectAllHandlerMappings" is turned off.
	 * @see #setDetectAllHandlerMappings
	 */
	public static final String HANDLER_MAPPING_BEAN_NAME = "handlerMapping";

	/**
	 * Well-known name for the HandlerAdapter object in the bean factory for this namespace.
	 * Only used when "detectAllHandlerAdapters" is turned off.
	 * @see #setDetectAllHandlerAdapters
	 */
	public static final String HANDLER_ADAPTER_BEAN_NAME = "handlerAdapter";

	/**
	 * Well-known name for the HandlerExceptionResolver object in the bean factory for this
	 * namespace. Only used when "detectAllHandlerExceptionResolvers" is turned off.
	 * @see #setDetectAllHandlerExceptionResolvers
	 */
	public static final String HANDLER_EXCEPTION_RESOLVER_BEAN_NAME = "handlerExceptionResolver";

	/**
	 * Well-known name for the RequestToViewNameTranslator object in the bean factory for
	 * this namespace.
	 */
	public static final String REQUEST_TO_VIEW_NAME_TRANSLATOR_BEAN_NAME = "viewNameTranslator";

	/**
	 * Well-known name for the ViewResolver object in the bean factory for this namespace.
	 * Only used when "detectAllViewResolvers" is turned off.
	 * @see #setDetectAllViewResolvers
	 */
	public static final String VIEW_RESOLVER_BEAN_NAME = "viewResolver";

	/**
	 * Request attribute to hold the currently chosen HandlerExecutionChain.
	 * Only used for internal optimizations.
	 */
	public static final String HANDLER_EXECUTION_CHAIN_ATTRIBUTE = DispatcherServlet.class.getName() + ".HANDLER";

	/**
	 * Request attribute to hold the current web application context.
	 * Otherwise only the global web app context is obtainable by tags etc.
	 * @see org.springframework.web.servlet.support.RequestContextUtils#getWebApplicationContext
	 */
	public static final String WEB_APPLICATION_CONTEXT_ATTRIBUTE = DispatcherServlet.class.getName() + ".CONTEXT";

	/**
	 * Request attribute to hold the current LocaleResolver, retrievable by views.
	 * @see org.springframework.web.servlet.support.RequestContextUtils#getLocaleResolver
	 */
	public static final String LOCALE_RESOLVER_ATTRIBUTE = DispatcherServlet.class.getName() + ".LOCALE_RESOLVER";

	/**
	 * Request attribute to hold the current ThemeResolver, retrievable by views.
	 * @see org.springframework.web.servlet.support.RequestContextUtils#getThemeResolver
	 */
	public static final String THEME_RESOLVER_ATTRIBUTE = DispatcherServlet.class.getName() + ".THEME_RESOLVER";

	/**
	 * Request attribute to hold the current ThemeSource, retrievable by views.
	 * @see org.springframework.web.servlet.support.RequestContextUtils#getThemeSource
	 */
	public static final String THEME_SOURCE_ATTRIBUTE = DispatcherServlet.class.getName() + ".THEME_SOURCE";


	/**
	 * Log category to use when no mapped handler is found for a request.
	 */
	public static final String PAGE_NOT_FOUND_LOG_CATEGORY = "org.springframework.web.servlet.PageNotFound";

	/**
	 * Name of the class path resource (relative to the DispatcherServlet class)
	 * that defines DispatcherServlet's default strategy names.
	 */
	private static final String DEFAULT_STRATEGIES_PATH = "DispatcherServlet.properties";


	/**
	 * Additional logger to use when no mapped handler is found for a request.
	 */
	protected static final Log pageNotFoundLogger = LogFactory.getLog(PAGE_NOT_FOUND_LOG_CATEGORY);

	private static final Properties defaultStrategies;

	static {
		// Load default strategy implementations from properties file.
		// This is currently strictly internal and not meant to be customized
		// by application developers.
		try {
			ClassPathResource resource = new ClassPathResource(DEFAULT_STRATEGIES_PATH, DispatcherServlet.class);
			defaultStrategies = PropertiesLoaderUtils.loadProperties(resource);
		}
		catch (IOException ex) {
			throw new IllegalStateException("Could not load 'DispatcherServlet.properties': " + ex.getMessage());
		}
	}


	/** Detect all HandlerMappings or just expect "handlerMapping" bean? */
	private boolean detectAllHandlerMappings = true;

	/** Detect all HandlerAdapters or just expect "handlerAdapter" bean? */
	private boolean detectAllHandlerAdapters = true;

	/** Detect all HandlerExceptionResolvers or just expect "handlerExceptionResolver" bean? */
	private boolean detectAllHandlerExceptionResolvers = true;

	/** Detect all ViewResolvers or just expect "viewResolver" bean? */
	private boolean detectAllViewResolvers = true;

	/** Perform cleanup of request attributes after include request? */
	private boolean cleanupAfterInclude = true;

	/** Expose LocaleContext and RequestAttributes as inheritable for child threads? */
	private boolean threadContextInheritable = false;


	/** MultipartResolver used by this servlet */
	private MultipartResolver multipartResolver;

	/** LocaleResolver used by this servlet */
	private LocaleResolver localeResolver;

	/** ThemeResolver used by this servlet */
	private ThemeResolver themeResolver;

	/** List of HandlerMappings used by this servlet */
	private List handlerMappings;

	/** List of HandlerAdapters used by this servlet */
	private List handlerAdapters;

	/** List of HandlerExceptionResolvers used by this servlet */
	private List handlerExceptionResolvers;

	/** RequestToViewNameTranslator used by this servlet */
	private RequestToViewNameTranslator viewNameTranslator;

	/** List of ViewResolvers used by this servlet */
	private List viewResolvers;


	/**
	 * Set whether to detect all HandlerMapping beans in this servlet's context.
	 * Else, just a single bean with name "handlerMapping" will be expected.
	 * <p>Default is "true". Turn this off if you want this servlet to use a
	 * single HandlerMapping, despite multiple HandlerMapping beans being
	 * defined in the context.
	 */
	public void setDetectAllHandlerMappings(boolean detectAllHandlerMappings) {
		this.detectAllHandlerMappings = detectAllHandlerMappings;
	}

	/**