Java tutorial
/* * 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 * * https://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.Locale; import java.util.Map; import java.util.TimeZone; import javax.servlet.ServletContext; import javax.servlet.ServletRequest; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import org.springframework.context.i18n.LocaleContext; import org.springframework.context.i18n.TimeZoneAwareLocaleContext; import org.springframework.lang.Nullable; import org.springframework.ui.context.Theme; import org.springframework.ui.context.ThemeSource; import org.springframework.util.Assert; import org.springframework.util.CollectionUtils; import org.springframework.web.context.ContextLoader; import org.springframework.web.context.WebApplicationContext; import org.springframework.web.context.support.WebApplicationContextUtils; import org.springframework.web.servlet.DispatcherServlet; import org.springframework.web.servlet.FlashMap; import org.springframework.web.servlet.FlashMapManager; import org.springframework.web.servlet.LocaleContextResolver; import org.springframework.web.servlet.LocaleResolver; import org.springframework.web.servlet.ThemeResolver; import org.springframework.web.util.UriComponents; import org.springframework.web.util.UriComponentsBuilder; /** * Utility class for easy access to request-specific state which has been * set by the {@link org.springframework.web.servlet.DispatcherServlet}. * * <p>Supports lookup of current WebApplicationContext, LocaleResolver, * Locale, ThemeResolver, Theme, and MultipartResolver. * * @author Juergen Hoeller * @author Rossen Stoyanchev * @since 03.03.2003 * @see RequestContext * @see org.springframework.web.servlet.DispatcherServlet */ public abstract class RequestContextUtils { /** * The name of the bean to use to look up in an implementation of * {@link RequestDataValueProcessor} has been configured. * @since 4.2.1 */ public static final String REQUEST_DATA_VALUE_PROCESSOR_BEAN_NAME = "requestDataValueProcessor"; /** * Look for the WebApplicationContext associated with the DispatcherServlet * that has initiated request processing, and for the global context if none * was found associated with the current request. The global context will * be found via the ServletContext or via ContextLoader's current context. * <p>NOTE: This variant remains compatible with Servlet 2.5, explicitly * checking a given ServletContext instead of deriving it from the request. * @param request current HTTP request * @param servletContext current servlet context * @return the request-specific WebApplicationContext, or the global one * if no request-specific context has been found, or {@code null} if none * @since 4.2.1 * @see DispatcherServlet#WEB_APPLICATION_CONTEXT_ATTRIBUTE * @see WebApplicationContextUtils#getWebApplicationContext(ServletContext) * @see ContextLoader#getCurrentWebApplicationContext() */ @Nullable public static WebApplicationContext findWebApplicationContext(HttpServletRequest request, @Nullable ServletContext servletContext) { WebApplicationContext webApplicationContext = (WebApplicationContext) request .getAttribute(DispatcherServlet.WEB_APPLICATION_CONTEXT_ATTRIBUTE); if (webApplicationContext == null) { if (servletContext != null) { webApplicationContext = WebApplicationContextUtils.getWebApplicationContext(servletContext); } if (webApplicationContext == null) { webApplicationContext = ContextLoader.getCurrentWebApplicationContext(); } } return webApplicationContext; } /** * Look for the WebApplicationContext associated with the DispatcherServlet * that has initiated request processing, and for the global context if none * was found associated with the current request. The global context will * be found via the ServletContext or via ContextLoader's current context. * <p>NOTE: This variant requires Servlet 3.0+ and is generally recommended * for forward-looking custom user code. * @param request current HTTP request * @return the request-specific WebApplicationContext, or the global one * if no request-specific context has been found, or {@code null} if none * @since 4.2.1 * @see #findWebApplicationContext(HttpServletRequest, ServletContext) * @see ServletRequest#getServletContext() * @see ContextLoader#getCurrentWebApplicationContext() */ @Nullable public static WebApplicationContext findWebApplicationContext(HttpServletRequest request) { return findWebApplicationContext(request, request.getServletContext()); } /** * Return the LocaleResolver that has been bound to the request by the * DispatcherServlet. * @param request current HTTP request * @return the current LocaleResolver, or {@code null} if not found */ @Nullable public static LocaleResolver getLocaleResolver(HttpServletRequest request) { return (LocaleResolver) request.getAttribute(DispatcherServlet.LOCALE_RESOLVER_ATTRIBUTE); } /** * Retrieve the current locale from the given request, using the * LocaleResolver bound to the request by the DispatcherServlet * (if available), falling back to the request's accept-header Locale. * <p>This method serves as a straightforward alternative to the standard * Servlet {@link javax.servlet.http.HttpServletRequest#getLocale()} method, * falling back to the latter if no more specific locale has been found. * <p>Consider using {@link org.springframework.context.i18n.LocaleContextHolder#getLocale()} * which will normally be populated with the same Locale. * @param request current HTTP request * @return the current locale for the given request, either from the * LocaleResolver or from the plain request itself * @see #getLocaleResolver * @see org.springframework.context.i18n.LocaleContextHolder#getLocale() */ public static Locale getLocale(HttpServletRequest request) { LocaleResolver localeResolver = getLocaleResolver(request); return (localeResolver != null ? localeResolver.resolveLocale(request) : request.getLocale()); } /** * Retrieve the current time zone from the given request, using the * TimeZoneAwareLocaleResolver bound to the request by the DispatcherServlet * (if available), falling back to the system's default time zone. * <p>Note: This method returns {@code null} if no specific time zone can be * resolved for the given request. This is in contrast to {@link #getLocale} * where there is always the request's accept-header locale to fall back to. * <p>Consider using {@link org.springframework.context.i18n.LocaleContextHolder#getTimeZone()} * which will normally be populated with the same TimeZone: That method only * differs in terms of its fallback to the system time zone if the LocaleResolver * hasn't provided a specific time zone (instead of this method's {@code null}). * @param request current HTTP request * @return the current time zone for the given request, either from the * TimeZoneAwareLocaleResolver or {@code null} if none associated * @see #getLocaleResolver * @see org.springframework.context.i18n.LocaleContextHolder#getTimeZone() */ @Nullable public static TimeZone getTimeZone(HttpServletRequest request) { LocaleResolver localeResolver = getLocaleResolver(request); if (localeResolver instanceof LocaleContextResolver) { LocaleContext localeContext = ((LocaleContextResolver) localeResolver).resolveLocaleContext(request); if (localeContext instanceof TimeZoneAwareLocaleContext) { return ((TimeZoneAwareLocaleContext) localeContext).getTimeZone(); } } return null; } /** * Return the ThemeResolver that has been bound to the request by the * DispatcherServlet. * @param request current HTTP request * @return the current ThemeResolver, or {@code null} if not found */ @Nullable public static ThemeResolver getThemeResolver(HttpServletRequest request) { return (ThemeResolver) request.getAttribute(DispatcherServlet.THEME_RESOLVER_ATTRIBUTE); } /** * Return the ThemeSource that has been bound to the request by the * DispatcherServlet. * @param request current HTTP request * @return the current ThemeSource */ @Nullable public static ThemeSource getThemeSource(HttpServletRequest request) { return (ThemeSource) request.getAttribute(DispatcherServlet.THEME_SOURCE_ATTRIBUTE); } /** * Retrieves the current theme from the given request, using the ThemeResolver * and ThemeSource bound to the request by the DispatcherServlet. * @param request current HTTP request * @return the current theme, or {@code null} if not found * @see #getThemeResolver */ @Nullable public static Theme getTheme(HttpServletRequest request) { ThemeResolver themeResolver = getThemeResolver(request); ThemeSource themeSource = getThemeSource(request); if (themeResolver != null && themeSource != null) { String themeName = themeResolver.resolveThemeName(request); return themeSource.getTheme(themeName); } else { return null; } } /** * Return read-only "input" flash attributes from request before redirect. * @param request current request * @return a read-only Map, or {@code null} if not found * @see FlashMap */ @SuppressWarnings("unchecked") @Nullable public static Map<String, ?> getInputFlashMap(HttpServletRequest request) { return (Map<String, ?>) request.getAttribute(DispatcherServlet.INPUT_FLASH_MAP_ATTRIBUTE); } /** * Return "output" FlashMap to save attributes for request after redirect. * @param request current request * @return a {@link FlashMap} instance, never {@code null} within a * {@code DispatcherServlet}-handled request */ public static FlashMap getOutputFlashMap(HttpServletRequest request) { return (FlashMap) request.getAttribute(DispatcherServlet.OUTPUT_FLASH_MAP_ATTRIBUTE); } /** * Return the {@code FlashMapManager} instance to save flash attributes. * <p>As of 5.0 the convenience method {@link #saveOutputFlashMap} may be * used to save the "output" FlashMap. * @param request the current request * @return a {@link FlashMapManager} instance, never {@code null} within a * {@code DispatcherServlet}-handled request */ @Nullable public static FlashMapManager getFlashMapManager(HttpServletRequest request) { return (FlashMapManager) request.getAttribute(DispatcherServlet.FLASH_MAP_MANAGER_ATTRIBUTE); } /** * Convenience method that retrieves the {@link #getOutputFlashMap "output" * FlashMap}, updates it with the path and query params of the target URL, * and then saves it using the {@link #getFlashMapManager FlashMapManager}. * @param location the target URL for the redirect * @param request the current request * @param response the current response * @since 5.0 */ public static void saveOutputFlashMap(String location, HttpServletRequest request, HttpServletResponse response) { FlashMap flashMap = getOutputFlashMap(request); if (CollectionUtils.isEmpty(flashMap)) { return; } UriComponents uriComponents = UriComponentsBuilder.fromUriString(location).build(); flashMap.setTargetRequestPath(uriComponents.getPath()); flashMap.addTargetRequestParams(uriComponents.getQueryParams()); FlashMapManager manager = getFlashMapManager(request); Assert.state(manager != null, "No FlashMapManager. Is this a DispatcherServlet handled request?"); manager.saveOutputFlashMap(flashMap, request, response); } }