requestcontext.java

spring framework 2.5.4源代码

/*
 * Copyright 2002-2008 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.support;

import java.util.HashMap;
import java.util.List;
import java.util.Locale;
import java.util.Map;

import javax.servlet.ServletContext;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpSession;
import javax.servlet.jsp.jstl.core.Config;

import org.springframework.context.MessageSource;
import org.springframework.context.MessageSourceResolvable;
import org.springframework.context.NoSuchMessageException;
import org.springframework.ui.context.Theme;
import org.springframework.ui.context.ThemeSource;
import org.springframework.ui.context.support.ResourceBundleThemeSource;
import org.springframework.util.Assert;
import org.springframework.util.ClassUtils;
import org.springframework.validation.BindException;
import org.springframework.validation.BindingResult;
import org.springframework.validation.Errors;
import org.springframework.web.bind.EscapedErrors;
import org.springframework.web.context.WebApplicationContext;
import org.springframework.web.servlet.LocaleResolver;
import org.springframework.web.util.HtmlUtils;
import org.springframework.web.util.UrlPathHelper;
import org.springframework.web.util.WebUtils;

/**
 * Context holder for request-specific state, like current web application
 * context, current locale, current theme, and potential binding errors.
 * Provides easy access to localized messages and Errors instances.
 *
 * <p>Suitable for exposition to views, and usage within JSP's "useBean" tag,
 * JSP scriptlets, JSTL EL, Velocity templates, etc. Necessary for views
 * that do not have access to the servlet request, like Velocity templates.
 *
 * <p>Can be instantiated manually, or automatically exposed to views as
 * model attribute via AbstractView's "requestContextAttribute" property.
 *
 * <p>Will also work outside of DispatcherServlet requests, accessing the root
 * WebApplicationContext and using an appropriate fallback for the locale
 * (the HttpServletRequest's primary locale).
 *
 * @author Juergen Hoeller
 * @since 03.03.2003
 * @see org.springframework.web.servlet.DispatcherServlet
 * @see org.springframework.web.servlet.view.AbstractView#setRequestContextAttribute
 * @see org.springframework.web.servlet.view.UrlBasedViewResolver#setRequestContextAttribute
 * @see #getFallbackLocale()
 */
public class RequestContext {

	/**
	 * Default theme name used if the RequestContext cannot find a ThemeResolver.
	 * Only applies to non-DispatcherServlet requests.
	 * <p>Same as AbstractThemeResolver's default, but not linked in here to
	 * avoid package interdependencies.
	 * @see org.springframework.web.servlet.theme.AbstractThemeResolver#ORIGINAL_DEFAULT_THEME_NAME
	 */
	public static final String DEFAULT_THEME_NAME = "theme";

	/**
	 * Request attribute to hold the current web application context for RequestContext usage.
	 * By default, the DispatcherServlet's context (or the root context as fallback) is exposed.
	 */
	public static final String WEB_APPLICATION_CONTEXT_ATTRIBUTE = RequestContext.class.getName() + ".CONTEXT";


	protected static final boolean jstlPresent = ClassUtils.isPresent(
			"javax.servlet.jsp.jstl.core.Config", JspAwareRequestContext.class.getClassLoader());


	private HttpServletRequest request;

	private Map model;

	private WebApplicationContext webApplicationContext;

	private Locale locale;

	private Theme theme;

	private Boolean defaultHtmlEscape;

	private UrlPathHelper urlPathHelper;

	private Map errorsMap;


	/**
	 * Create a new RequestContext for the given request,
	 * using the request attributes for Errors retrieval.
	 * <p>This only works with InternalResourceViews, as Errors instances
	 * are part of the model and not normally exposed as request attributes.
	 * It will typically be used within JSPs or custom tags.
	 * <p><b>Will only work within a DispatcherServlet request.</b> Pass in a
	 * ServletContext to be able to fallback to the root WebApplicationContext.
	 * @param request current HTTP request
	 * @see org.springframework.web.servlet.DispatcherServlet
	 * @see #RequestContext(javax.servlet.http.HttpServletRequest, javax.servlet.ServletContext)
	 */
	public RequestContext(HttpServletRequest request) {
		initContext(request, null, null);
	}

	/**
	 * Create a new RequestContext for the given request,
	 * using the request attributes for Errors retrieval.
	 * <p>This only works with InternalResourceViews, as Errors instances
	 * are part of the model and not normally exposed as request attributes.
	 * It will typically be used within JSPs or custom tags.
	 * <p>If a ServletContext is specified, the RequestContext will also
	 * work with the root WebApplicationContext (outside a DispatcherServlet).
	 * @param request current HTTP request
	 * @param servletContext the servlet context of the web application
	 * (can be <code>null</code>; necessary for fallback to root WebApplicationContext)
	 * @see org.springframework.web.context.WebApplicationContext
	 * @see org.springframework.web.servlet.DispatcherServlet
	 */
	public RequestContext(HttpServletRequest request, ServletContext servletContext) {
		initContext(request, servletContext, null);
	}

	/**
	 * Create a new RequestContext for the given request,
	 * using the given model attributes for Errors retrieval.
	 * <p>This works with all View implementations.
	 * It will typically be used by View implementations.
	 * <p><b>Will only work within a DispatcherServlet request.</b> Pass in a
	 * ServletContext to be able to fallback to the root WebApplicationContext.
	 * @param request current HTTP request
	 * @param model the model attributes for the current view
	 * (can be <code>null</code>, using the request attributes for Errors retrieval)
	 * @see org.springframework.web.servlet.DispatcherServlet
	 * @see #RequestContext(javax.servlet.http.HttpServletRequest, javax.servlet.ServletContext, Map)
	 */
	public RequestContext(HttpServletRequest request, Map model) {
		initContext(request, null, model);
	}

	/**
	 * Create a new RequestContext for the given request,
	 * using the given model attributes for Errors retrieval.
	 * <p>This works with all View implementations.
	 * It will typically be used by View implementations.
	 * <p>If a ServletContext is specified, the RequestContext will also
	 * work with a root WebApplicationContext (outside a DispatcherServlet).
	 * @param request current HTTP request
	 * @param servletContext the servlet context of the web application
	 * (can be <code>null</code>; necessary for fallback to root WebApplicationContext)
	 * @param model the model attributes for the current view
	 * (can be <code>null</code>, using the request attributes for Errors retrieval)
	 * @see org.springframework.web.context.WebApplicationContext
	 * @see org.springframework.web.servlet.DispatcherServlet
	 */
	public RequestContext(HttpServletRequest request, ServletContext servletContext, Map model) {
		initContext(request, servletContext, model);
	}

	/**
	 * Default constructor for subclasses.
	 */
	protected RequestContext() {
	}


	/**
	 * Initialize this context with the given request,
	 * using the given model attributes for Errors retrieval.
	 * <p>Delegates to <code>getFallbackLocale</code> and <code>getFallbackTheme</code>
	 * for determining the fallback locale and theme, respectively, if no LocaleResolver
	 * and/or ThemeResolver can be found in the request.
	 * @param request current HTTP request
	 * @param servletContext the servlet context of the web application
	 * (can be <code>null</code>; necessary for fallback to root WebApplicationContext)
	 * @param model the model attributes for the current view
	 * (can be <code>null</code>, using the request attributes for Errors retrieval)
	 * @see #getFallbackLocale
	 * @see #getFallbackTheme
	 * @see org.springframework.web.servlet.DispatcherServlet#LOCALE_RESOLVER_ATTRIBUTE
	 * @see org.springframework.web.servlet.DispatcherServlet#THEME_RESOLVER_ATTRIBUTE
	 */
	protected void initContext(HttpServletRequest request, ServletContext servletContext, Map model) {
		this.request = request;
		this.model = model;

		// Fetch WebApplicationContext, either from DispatcherServlet or the root context.
		// ServletContext needs to be specified to be able to fall back to the root context!
		this.webApplicationContext =
				(WebApplicationContext) request.getAttribute(WEB_APPLICATION_CONTEXT_ATTRIBUTE);
		if (this.webApplicationContext == null) {
			this.webApplicationContext = RequestContextUtils.getWebApplicationContext(request, servletContext);
		}

		// Determine locale to use for this RequestContext.
		LocaleResolver localeResolver = RequestContextUtils.getLocaleResolver(request);
		if (localeResolver != null) {
			// Try LocaleResolver (we're within a DispatcherServlet request).
			this.locale = localeResolver.resolveLocale(request);
		}
		else {
			// No LocaleResolver available -> try fallback.
			this.locale = getFallbackLocale();
		}

		// Determine default HTML escape setting from the "defaultHtmlEscape"
		// context-param in web.xml, if any.
		this.defaultHtmlEscape = WebUtils.getDefaultHtmlEscape(this.webApplicationContext.getServletContext());

		this.urlPathHelper = new UrlPathHelper();
	}

	/**
	 * Determine the fallback locale for this context.
	 * <p>The default implementation checks for a JSTL locale attribute
	 * in request, session or application scope; if not found,
	 * returns the <code>HttpServletRequest.getLocale()</code>.
	 * @return the fallback locale (never <code>null</code>)
	 * @see javax.servlet.http.HttpServletRequest#getLocale()
	 */
	protected Locale getFallbackLocale() {
		if (jstlPresent) {
			Locale locale = JstlLocaleResolver.getJstlLocale(getRequest(), getServletContext());
			if (locale != null) {
				return locale;
			}
		}
		return getRequest().getLocale();
	}

	/**
	 * Determine the fallback theme for this context.
	 * <p>The default implementation returns the default theme (with name "theme").
	 * @return the fallback theme (never <code>null</code>)
	 */
	protected Theme getFallbackTheme() {
		ThemeSource themeSource = RequestContextUtils.getThemeSource(getRequest());
		if (themeSource == null) {
			themeSource = new ResourceBundleThemeSource();
		}
		Theme theme = themeSource.getTheme(DEFAULT_THEME_NAME);
		if (theme == null) {
			throw new IllegalStateException("No theme defined and no fallback theme found");
		}
		return theme;
	}


	/**
	 * Return the underlying HttpServletRequest.
	 * Only intended for cooperating classes in this package.
	 */
	protected final HttpServletRequest getRequest() {
		return this.request;
	}

	/**
	 * Return the underlying ServletContext.
	 * Only intended for cooperating classes in this package.
	 */
	protected final ServletContext getServletContext() {
		return this.webApplicationContext.getServletContext();
	}

	/**
	 * Return the current WebApplicationContext.
	 */
	public final WebApplicationContext getWebApplicationContext() {
		return this.webApplicationContext;
	}

	/**
	 * Return the current WebApplicationContext as MessageSource.
	 */
	public final MessageSource getMessageSource() {
		return this.webApplicationContext;
	}

	/**
	 * Return the current locale.
	 */
	public final Locale getLocale() {
		return this.locale;
	}

	/**
	 * Return the current theme (never <code>null</code>).
	 * Resolved lazily for more efficiency when theme support is not used.
	 */
	public final Theme getTheme() {
		if (this.theme == null) {
			// Lazily determine theme to use for this RequestContext.
			this.theme = RequestContextUtils.getTheme(this.request);
			if (this.theme == null) {
				// No ThemeResolver and ThemeSource available -> try fallback.
				this.theme = getFallbackTheme();
			}
		}
		return this.theme;
	}


	/**
	 * (De)activate default HTML escaping for messages and errors, for the scope
	 * of this RequestContext. The default is the application-wide setting
	 * (the "defaultHtmlEscape" context-param in web.xml).
	 * @see org.springframework.web.util.WebUtils#isDefaultHtmlEscape
	 */
	public void setDefaultHtmlEscape(boolean defaultHtmlEscape) {
		this.defaultHtmlEscape = Boolean.valueOf(defaultHtmlEscape);
	}

	/**
	 * Is default HTML escaping active?
	 * Falls back to <code>false</code> in case of no explicit default given.
	 */
	public boolean isDefaultHtmlEscape() {
		return (this.defaultHtmlEscape != null && this.defaultHtmlEscape.booleanValue());
	}

	/**
	 * Return the default HTML escape setting, differentiating
	 * between no default specified and an explicit value.
	 * @return whether default HTML escaping is enabled (null = no explicit default)
	 */
	public Boolean getDefaultHtmlEscape() {
		return this.defaultHtmlEscape;
	}

	/**
	 * Set the UrlPathHelper to use for context path and request URI decoding.
	 * Can be used to pass a shared UrlPathHelper instance in.
	 * <p>A default UrlPathHelper is always available.
	 */
	public void setUrlPathHelper(UrlPathHelper urlPathHelper) {
		Assert.notNull(urlPathHelper, "UrlPathHelper must not be null");
		this.urlPathHelper = urlPathHelper;
	}

	/**
	 * Return the UrlPathHelper used for context path and request URI decoding.
	 * Can be used to configure the current UrlPathHelper.
	 * <p>A default UrlPathHelper is always available.
	 */
	public UrlPathHelper getUrlPathHelper() {
		return this.urlPathHelper;
	}


	/**