requestcontext.java

Java/J2EE application framework based on [Expert One-on-One J2EE Design and Development] by Rod John

/*
 * Copyright 2002-2004 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.Locale;
import java.util.Map;

import javax.servlet.http.HttpServletRequest;

import org.springframework.context.MessageSourceResolvable;
import org.springframework.context.NoSuchMessageException;
import org.springframework.ui.context.Theme;
import org.springframework.validation.BindException;
import org.springframework.validation.Errors;
import org.springframework.web.bind.EscapedErrors;
import org.springframework.web.context.WebApplicationContext;
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.
 *
 * @author Juergen Hoeller
 * @since 03.03.2003
 * @see org.springframework.web.servlet.view.AbstractView#setRequestContextAttribute
 * @see org.springframework.web.servlet.view.UrlBasedViewResolver#setRequestContextAttribute
 */
public class RequestContext {

	private final HttpServletRequest request;

	private final Map model;

	private final WebApplicationContext webApplicationContext;

	private final Locale locale;

	private final 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.
	 * @param request current HTTP request
	 */
	public RequestContext(HttpServletRequest request) {
		this(request, 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.
	 * @param request current HTTP request
	 * @param model the model attributes for the current view
	 */
	public RequestContext(HttpServletRequest request, Map model) {
		this.request = request;
		this.model = model;
		this.webApplicationContext = RequestContextUtils.getWebApplicationContext(request);
		this.locale = RequestContextUtils.getLocale(request);
		this.theme = RequestContextUtils.getTheme(request);
		this.defaultHtmlEscape = WebUtils.isDefaultHtmlEscape(this.webApplicationContext.getServletContext());
		this.urlPathHelper = new UrlPathHelper();
	}

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

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

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

	/**
	 * Return the current theme.
	 */
	public Theme getTheme() {
		return 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 = defaultHtmlEscape;
	}

	/**
	 * Is default HTML escaping active?
	 */
	public boolean isDefaultHtmlEscape() {
		return 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) {
		this.urlPathHelper = (urlPathHelper != null ? urlPathHelper : new 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 urlPathHelper;
	}


	/**
	 * Return the context path of the current request,
	 * i.e. the path that indicates the current web application.
	 * <p>Delegates to the UrlPathHelper for decoding.
	 * @see javax.servlet.http.HttpServletRequest#getContextPath
	 * @see #getUrlPathHelper
	 */
	public String getContextPath() {
		return this.urlPathHelper.getContextPath(this.request);
	}

	/**
	 * Return the request URI of the current request, i.e. the invoked URL
	 * without parameters. This is particularly useful as HTML form action target.
	 * <p><b>Note that you should create your RequestContext instance <i>before</i>
	 * forwarding to your JSP view, if you intend to determine the request URI!</b>
	 * The optimal way to do so is to set "requestContextAttribute" on your view.
	 * Else, you'll get the URI of your JSP rather than the one of your controller.
	 * <p>Side note: As alternative for an HTML form action, either specify
	 * an empty "action" or omit the "action" attribute completely. This is
	 * not covered by the HTML spec, though, but known to work reliably on
	 * all current browsers.
	 * <p>Delegates to the UrlPathHelper for decoding.
	 * @see javax.servlet.http.HttpServletRequest#getRequestURI
	 * @see #getUrlPathHelper
	 * @see org.springframework.web.servlet.view.AbstractView#setRequestContextAttribute
	 * @see org.springframework.web.servlet.view.UrlBasedViewResolver#setRequestContextAttribute
	 */
	public String getRequestUri() {
		return this.urlPathHelper.getRequestUri(this.request);
	}


	/**
	 * Retrieve the message for the given code, using the defaultHtmlEscape setting.
	 * @param code code of the message
	 * @param defaultMessage String to return if the lookup fails
	 * @return the message
	 */
	public String getMessage(String code, String defaultMessage) {
		return getMessage(code, null, defaultMessage, this.defaultHtmlEscape);
	}

	/**
	 * Retrieve the message for the given code, using the defaultHtmlEscape setting.
	 * @param code code of the message
	 * @param args arguments for the message, or null if none
	 * @param defaultMessage String to return if the lookup fails
	 * @return the message
	 */
	public String getMessage(String code, Object[] args, String defaultMessage) {
		return getMessage(code, args, defaultMessage, this.defaultHtmlEscape);
	}