https://github.com/spring-projects/spring-framework: Spring Web (Spring IO)
  • Juergen Hoeller 
/*
 * 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.context.support;

import java.io.Serializable;
import java.util.Collections;
import java.util.Enumeration;
import java.util.HashMap;
import java.util.Map;
import javax.faces.context.ExternalContext;
import javax.faces.context.FacesContext;
import javax.servlet.ServletConfig;
import javax.servlet.ServletContext;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpSession;

import org.springframework.beans.factory.ObjectFactory;
import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
import org.springframework.core.env.MutablePropertySources;
import org.springframework.core.env.PropertySource.StubPropertySource;
import org.springframework.lang.Nullable;
import org.springframework.util.Assert;
import org.springframework.util.ClassUtils;
import org.springframework.web.context.ConfigurableWebApplicationContext;
import org.springframework.web.context.WebApplicationContext;
import org.springframework.web.context.request.RequestAttributes;
import org.springframework.web.context.request.RequestContextHolder;
import org.springframework.web.context.request.RequestScope;
import org.springframework.web.context.request.ServletRequestAttributes;
import org.springframework.web.context.request.ServletWebRequest;
import org.springframework.web.context.request.SessionScope;
import org.springframework.web.context.request.WebRequest;


Convenience methods for retrieving the root WebApplicationContext for a given ServletContext. This is useful for programmatically accessing a Spring application context from within custom web views or MVC actions. 
Note that there are more convenient ways of accessing the root context for
many web frameworks, either part of Spring or available as an external library.
This helper class is just the most generic way to access the root context.

Author:Juergen Hoeller
See Also:
/**
 * Convenience methods for retrieving the root {@link WebApplicationContext} for
 * a given {@link ServletContext}. This is useful for programmatically accessing
 * a Spring application context from within custom web views or MVC actions.
 *
 * <p>Note that there are more convenient ways of accessing the root context for
 * many web frameworks, either part of Spring or available as an external library.
 * This helper class is just the most generic way to access the root context.
 *
 * @author Juergen Hoeller
 * @see org.springframework.web.context.ContextLoader
 * @see org.springframework.web.servlet.FrameworkServlet
 * @see org.springframework.web.servlet.DispatcherServlet
 * @see org.springframework.web.jsf.FacesContextUtils
 * @see org.springframework.web.jsf.el.SpringBeanFacesELResolver
 */
public abstract class WebApplicationContextUtils {

	private static final boolean jsfPresent =
			ClassUtils.isPresent("javax.faces.context.FacesContext", RequestContextHolder.class.getClassLoader());


	
Find the root WebApplicationContext for this web app, typically loaded via ContextLoaderListener. 
Will rethrow an exception that happened on root context startup,
to differentiate between a failed context startup and no context at all.

Params:
  • sc – the ServletContext to find the web application context for
Throws:
See Also:
Returns:the root WebApplicationContext for this web app
/**
	 * Find the root {@code WebApplicationContext} for this web app, typically
	 * loaded via {@link org.springframework.web.context.ContextLoaderListener}.
	 * <p>Will rethrow an exception that happened on root context startup,
	 * to differentiate between a failed context startup and no context at all.
	 * @param sc the ServletContext to find the web application context for
	 * @return the root WebApplicationContext for this web app
	 * @throws IllegalStateException if the root WebApplicationContext could not be found
	 * @see org.springframework.web.context.WebApplicationContext#ROOT_WEB_APPLICATION_CONTEXT_ATTRIBUTE
	 */
	public static WebApplicationContext getRequiredWebApplicationContext(ServletContext sc) throws IllegalStateException {
		WebApplicationContext wac = getWebApplicationContext(sc);
		if (wac == null) {
			throw new IllegalStateException("No WebApplicationContext found: no ContextLoaderListener registered?");
		}
		return wac;
	}

	
Find the root WebApplicationContext for this web app, typically loaded via ContextLoaderListener. 
Will rethrow an exception that happened on root context startup,
to differentiate between a failed context startup and no context at all.

Params:
  • sc – the ServletContext to find the web application context for
See Also:
Returns:the root WebApplicationContext for this web app, or null if none
/**
	 * Find the root {@code WebApplicationContext} for this web app, typically
	 * loaded via {@link org.springframework.web.context.ContextLoaderListener}.
	 * <p>Will rethrow an exception that happened on root context startup,
	 * to differentiate between a failed context startup and no context at all.
	 * @param sc the ServletContext to find the web application context for
	 * @return the root WebApplicationContext for this web app, or {@code null} if none
	 * @see org.springframework.web.context.WebApplicationContext#ROOT_WEB_APPLICATION_CONTEXT_ATTRIBUTE
	 */
	@Nullable
	public static WebApplicationContext getWebApplicationContext(ServletContext sc) {
		return getWebApplicationContext(sc, WebApplicationContext.ROOT_WEB_APPLICATION_CONTEXT_ATTRIBUTE);
	}

	
Find a custom WebApplicationContext for this web app. 
Params:
  • sc – the ServletContext to find the web application context for
  • attrName – the name of the ServletContext attribute to look for
Returns:the desired WebApplicationContext for this web app, or null if none
/**
	 * Find a custom {@code WebApplicationContext} for this web app.
	 * @param sc the ServletContext to find the web application context for
	 * @param attrName the name of the ServletContext attribute to look for
	 * @return the desired WebApplicationContext for this web app, or {@code null} if none
	 */
	@Nullable
	public static WebApplicationContext getWebApplicationContext(ServletContext sc, String attrName) {
		Assert.notNull(sc, "ServletContext must not be null");
		Object attr = sc.getAttribute(attrName);
		if (attr == null) {
			return null;
		}
		if (attr instanceof RuntimeException) {
			throw (RuntimeException) attr;
		}
		if (attr instanceof Error) {
			throw (Error) attr;
		}
		if (attr instanceof Exception) {
			throw new IllegalStateException((Exception) attr);
		}
		if (!(attr instanceof WebApplicationContext)) {
			throw new IllegalStateException("Context attribute is not of type WebApplicationContext: " + attr);
		}
		return (WebApplicationContext) attr;
	}

	
Find a unique WebApplicationContext for this web app: either the root web app context (preferred) or a unique WebApplicationContext among the registered ServletContext attributes (typically coming from a single DispatcherServlet in the current web application). 
Note that DispatcherServlet's exposure of its context can be controlled through its publishContext property, which is true by default but can be selectively switched to only publish a single context despite multiple DispatcherServlet registrations in the web app. 
Params:
  • sc – the ServletContext to find the web application context for
See Also:
Returns:the desired WebApplicationContext for this web app, or null if none
Since:4.2
/**
	 * Find a unique {@code WebApplicationContext} for this web app: either the
	 * root web app context (preferred) or a unique {@code WebApplicationContext}
	 * among the registered {@code ServletContext} attributes (typically coming
	 * from a single {@code DispatcherServlet} in the current web application).
	 * <p>Note that {@code DispatcherServlet}'s exposure of its context can be
	 * controlled through its {@code publishContext} property, which is {@code true}
	 * by default but can be selectively switched to only publish a single context
	 * despite multiple {@code DispatcherServlet} registrations in the web app.
	 * @param sc the ServletContext to find the web application context for
	 * @return the desired WebApplicationContext for this web app, or {@code null} if none
	 * @since 4.2
	 * @see #getWebApplicationContext(ServletContext)
	 * @see ServletContext#getAttributeNames()
	 */
	@Nullable
	public static WebApplicationContext findWebApplicationContext(ServletContext sc) {
		WebApplicationContext wac = getWebApplicationContext(sc);
		if (wac == null) {
			Enumeration<String> attrNames = sc.getAttributeNames();
			while (attrNames.hasMoreElements()) {
				String attrName = attrNames.nextElement();
				Object attrValue = sc.getAttribute(attrName);
				if (attrValue instanceof WebApplicationContext) {
					if (wac != null) {
						throw new IllegalStateException("No unique WebApplicationContext found: more than one " +
								"DispatcherServlet registered with publishContext=true?");
					}
					wac = (WebApplicationContext) attrValue;
				}
			}
		}
		return wac;
	}


	
Register web-specific scopes ("request", "session", "globalSession")
with the given BeanFactory, as used by the WebApplicationContext.

Params:
  • beanFactory – the BeanFactory to configure
/**
	 * Register web-specific scopes ("request", "session", "globalSession")
	 * with the given BeanFactory, as used by the WebApplicationContext.
	 * @param beanFactory the BeanFactory to configure
	 */
	public static void registerWebApplicationScopes(ConfigurableListableBeanFactory beanFactory) {
		registerWebApplicationScopes(beanFactory, null);
	}

	
Register web-specific scopes ("request", "session", "globalSession", "application")
with the given BeanFactory, as used by the WebApplicationContext.

Params:
  • beanFactory – the BeanFactory to configure
  • sc – the ServletContext that we're running within
/**
	 * Register web-specific scopes ("request", "session", "globalSession", "application")
	 * with the given BeanFactory, as used by the WebApplicationContext.
	 * @param beanFactory the BeanFactory to configure
	 * @param sc the ServletContext that we're running within
	 */
	public static void registerWebApplicationScopes(ConfigurableListableBeanFactory beanFactory,
			@Nullable ServletContext sc) {

		beanFactory.registerScope(WebApplicationContext.SCOPE_REQUEST, new RequestScope());
		beanFactory.registerScope(WebApplicationContext.SCOPE_SESSION, new SessionScope());
		if (sc != null) {
			ServletContextScope appScope = new ServletContextScope(sc);
			beanFactory.registerScope(WebApplicationContext.SCOPE_APPLICATION, appScope);
			// Register as ServletContext attribute, for ContextCleanupListener to detect it.
			sc.setAttribute(ServletContextScope.class.getName(), appScope);
		}

		beanFactory.registerResolvableDependency(ServletRequest.class, new RequestObjectFactory());
		beanFactory.registerResolvableDependency(ServletResponse.class, new ResponseObjectFactory());
		beanFactory.registerResolvableDependency(HttpSession.class, new SessionObjectFactory());
		beanFactory.registerResolvableDependency(WebRequest.class, new WebRequestObjectFactory());
		if (jsfPresent) {
			FacesDependencyRegistrar.registerFacesDependencies(beanFactory);
		}
	}

	
Register web-specific environment beans ("contextParameters", "contextAttributes")
with the given BeanFactory, as used by the WebApplicationContext.

Params:
  • bf – the BeanFactory to configure
  • sc – the ServletContext that we're running within
/**
	 * Register web-specific environment beans ("contextParameters", "contextAttributes")
	 * with the given BeanFactory, as used by the WebApplicationContext.
	 * @param bf the BeanFactory to configure
	 * @param sc the ServletContext that we're running within
	 */
	public static void registerEnvironmentBeans(ConfigurableListableBeanFactory bf, @Nullable ServletContext sc) {
		registerEnvironmentBeans(bf, sc, null);
	}

	
Register web-specific environment beans ("contextParameters", "contextAttributes")
with the given BeanFactory, as used by the WebApplicationContext.

Params:
  • bf – the BeanFactory to configure
  • servletContext – the ServletContext that we're running within
  • servletConfig – the ServletConfig
/**
	 * Register web-specific environment beans ("contextParameters", "contextAttributes")
	 * with the given BeanFactory, as used by the WebApplicationContext.
	 * @param bf the BeanFactory to configure
	 * @param servletContext the ServletContext that we're running within
	 * @param servletConfig the ServletConfig
	 */
	public static void registerEnvironmentBeans(ConfigurableListableBeanFactory bf,
			@Nullable ServletContext servletContext, @Nullable ServletConfig servletConfig) {

		if (servletContext != null && !bf.containsBean(WebApplicationContext.SERVLET_CONTEXT_BEAN_NAME)) {
			bf.registerSingleton(WebApplicationContext.SERVLET_CONTEXT_BEAN_NAME, servletContext);
		}

		if (servletConfig != null && !bf.containsBean(ConfigurableWebApplicationContext.SERVLET_CONFIG_BEAN_NAME)) {
			bf.registerSingleton(ConfigurableWebApplicationContext.SERVLET_CONFIG_BEAN_NAME, servletConfig);
		}

		if (!bf.containsBean(WebApplicationContext.CONTEXT_PARAMETERS_BEAN_NAME)) {
			Map<String, String> parameterMap = new HashMap<>();
			if (servletContext != null) {
				Enumeration<?> paramNameEnum = servletContext.getInitParameterNames();
				while (paramNameEnum.hasMoreElements()) {
					String paramName = (String) paramNameEnum.nextElement();
					parameterMap.put(paramName, servletContext.getInitParameter(paramName));
				}
			}
			if (servletConfig != null) {
				Enumeration<?> paramNameEnum = servletConfig.getInitParameterNames();
				while (paramNameEnum.hasMoreElements()) {
					String paramName = (String) paramNameEnum.nextElement();
					parameterMap.put(paramName, servletConfig.getInitParameter(paramName));
				}
			}
			bf.registerSingleton(WebApplicationContext.CONTEXT_PARAMETERS_BEAN_NAME,
					Collections.unmodifiableMap(parameterMap));
		}

		if (!bf.containsBean(WebApplicationContext.CONTEXT_ATTRIBUTES_BEAN_NAME)) {
			Map<String, Object> attributeMap = new HashMap<>();
			if (servletContext != null) {
				Enumeration<?> attrNameEnum = servletContext.getAttributeNames();
				while (attrNameEnum.hasMoreElements()) {
					String attrName = (String) attrNameEnum.nextElement();
					attributeMap.put(attrName, servletContext.getAttribute(attrName));
				}
			}
			bf.registerSingleton(WebApplicationContext.CONTEXT_ATTRIBUTES_BEAN_NAME,
					Collections.unmodifiableMap(attributeMap));
		}
	}

	
Convenient variant of initServletPropertySources(MutablePropertySources, ServletContext, ServletConfig) that always provides null for the ServletConfig parameter. 
See Also:
/**
	 * Convenient variant of {@link #initServletPropertySources(MutablePropertySources,
	 * ServletContext, ServletConfig)} that always provides {@code null} for the
	 * {@link ServletConfig} parameter.
	 * @see #initServletPropertySources(MutablePropertySources, ServletContext, ServletConfig)
	 */
	public static void initServletPropertySources(MutablePropertySources propertySources, ServletContext servletContext) {
		initServletPropertySources(propertySources, servletContext, null);
	}

	
Replace Servlet-based stub property sources with actual instances populated with the given servletContext and servletConfig objects. 
This method is idempotent with respect to the fact it may be called any number
of times but will perform replacement of stub property sources with their
corresponding actual property sources once and only once.

Params:
See Also:
/**
	 * Replace {@code Servlet}-based {@link StubPropertySource stub property sources} with
	 * actual instances populated with the given {@code servletContext} and
	 * {@code servletConfig} objects.
	 * <p>This method is idempotent with respect to the fact it may be called any number
	 * of times but will perform replacement of stub property sources with their
	 * corresponding actual property sources once and only once.
	 * @param sources the {@link MutablePropertySources} to initialize (must not
	 * be {@code null})
	 * @param servletContext the current {@link ServletContext} (ignored if {@code null}
	 * or if the {@link StandardServletEnvironment#SERVLET_CONTEXT_PROPERTY_SOURCE_NAME
	 * servlet context property source} has already been initialized)
	 * @param servletConfig the current {@link ServletConfig} (ignored if {@code null}
	 * or if the {@link StandardServletEnvironment#SERVLET_CONFIG_PROPERTY_SOURCE_NAME
	 * servlet config property source} has already been initialized)
	 * @see org.springframework.core.env.PropertySource.StubPropertySource
	 * @see org.springframework.core.env.ConfigurableEnvironment#getPropertySources()
	 */
	public static void initServletPropertySources(MutablePropertySources sources,
			@Nullable ServletContext servletContext, @Nullable ServletConfig servletConfig) {

		Assert.notNull(sources, "'propertySources' must not be null");
		String name = StandardServletEnvironment.SERVLET_CONTEXT_PROPERTY_SOURCE_NAME;
		if (servletContext != null && sources.contains(name) && sources.get(name) instanceof StubPropertySource) {
			sources.replace(name, new ServletContextPropertySource(name, servletContext));
		}
		name = StandardServletEnvironment.SERVLET_CONFIG_PROPERTY_SOURCE_NAME;
		if (servletConfig != null && sources.contains(name) && sources.get(name) instanceof StubPropertySource) {
			sources.replace(name, new ServletConfigPropertySource(name, servletConfig));
		}
	}

	
Return the current RequestAttributes instance as ServletRequestAttributes.

See Also:
  • currentRequestAttributes.currentRequestAttributes()
/**
	 * Return the current RequestAttributes instance as ServletRequestAttributes.
	 * @see RequestContextHolder#currentRequestAttributes()
	 */
	private static ServletRequestAttributes currentRequestAttributes() {
		RequestAttributes requestAttr = RequestContextHolder.currentRequestAttributes();
		if (!(requestAttr instanceof ServletRequestAttributes)) {
			throw new IllegalStateException("Current request is not a servlet request");
		}
		return (ServletRequestAttributes) requestAttr;
	}


	
Factory that exposes the current request object on demand.

/**
	 * Factory that exposes the current request object on demand.
	 */
	@SuppressWarnings("serial")
	private static class RequestObjectFactory implements ObjectFactory<ServletRequest>, Serializable {

		@Override
		public ServletRequest getObject() {
			return currentRequestAttributes().getRequest();
		}

		@Override
		public String toString() {
			return "Current HttpServletRequest";
		}
	}


	
Factory that exposes the current response object on demand.

/**
	 * Factory that exposes the current response object on demand.
	 */
	@SuppressWarnings("serial")
	private static class ResponseObjectFactory implements ObjectFactory<ServletResponse>, Serializable {

		@Override
		public ServletResponse getObject() {
			ServletResponse response = currentRequestAttributes().getResponse();
			if (response == null) {
				throw new IllegalStateException("Current servlet response not available - " +
						"consider using RequestContextFilter instead of RequestContextListener");
			}
			return response;
		}

		@Override
		public String toString() {
			return "Current HttpServletResponse";
		}
	}


	
Factory that exposes the current session object on demand.

/**
	 * Factory that exposes the current session object on demand.
	 */
	@SuppressWarnings("serial")
	private static class SessionObjectFactory implements ObjectFactory<HttpSession>, Serializable {

		@Override
		public HttpSession getObject() {
			return currentRequestAttributes().getRequest().getSession();
		}

		@Override
		public String toString() {
			return "Current HttpSession";
		}
	}


	
Factory that exposes the current WebRequest object on demand.

/**
	 * Factory that exposes the current WebRequest object on demand.
	 */
	@SuppressWarnings("serial")
	private static class WebRequestObjectFactory implements ObjectFactory<WebRequest>, Serializable {

		@Override
		public WebRequest getObject() {
			ServletRequestAttributes requestAttr = currentRequestAttributes();
			return new ServletWebRequest(requestAttr.getRequest(), requestAttr.getResponse());
		}

		@Override
		public String toString() {
			return "Current ServletWebRequest";
		}
	}


	
Inner class to avoid hard-coded JSF dependency.

/**
	 * Inner class to avoid hard-coded JSF dependency.
 	 */
	private static class FacesDependencyRegistrar {

		public static void registerFacesDependencies(ConfigurableListableBeanFactory beanFactory) {
			beanFactory.registerResolvableDependency(FacesContext.class, new ObjectFactory<FacesContext>() {
				@Override
				public FacesContext getObject() {
					return FacesContext.getCurrentInstance();
				}
				@Override
				public String toString() {
					return "Current JSF FacesContext";
				}
			});
			beanFactory.registerResolvableDependency(ExternalContext.class, new ObjectFactory<ExternalContext>() {
				@Override
				public ExternalContext getObject() {
					return FacesContext.getCurrentInstance().getExternalContext();
				}
				@Override
				public String toString() {
					return "Current JSF ExternalContext";
				}
			});
		}
	}

}