org.springframework.web.context.support.WebApplicationContextUtils Maven / Gradle / Ivy
/*
* Copyright 2002-2005 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 javax.servlet.ServletContext;
import org.springframework.util.Assert;
import org.springframework.web.context.WebApplicationContext;
/**
* Convenience methods to retrieve the root WebApplicationContext for a given
* ServletContext. This is e.g. useful for accessing a Spring context from
* within custom web views or Struts actions.
*
* Note that there are more convenient ways of accessing the root context for
* many web frameworks, either part of Spring or available as 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.struts.ActionSupport
* @see org.springframework.web.struts.DelegatingActionProxy
* @see org.springframework.web.jsf.FacesContextUtils
* @see org.springframework.web.jsf.DelegatingVariableResolver
*/
public abstract class WebApplicationContextUtils {
/**
* Find the root WebApplicationContext for this web application, which is
* typically loaded via ContextLoaderListener or ContextLoaderServlet.
*
Will rethrow an exception that happened on root context startup,
* to differentiate between a failed context startup and no context at all.
* @param sc ServletContext to find the web application context for
* @return the root WebApplicationContext for this web app, or null if none
* @see org.springframework.web.context.WebApplicationContext#ROOT_WEB_APPLICATION_CONTEXT_ATTRIBUTE
*/
public static WebApplicationContext getWebApplicationContext(ServletContext sc) {
Assert.notNull(sc, "ServletContext must not be null");
Object attr = sc.getAttribute(WebApplicationContext.ROOT_WEB_APPLICATION_CONTEXT_ATTRIBUTE);
if (attr == null) {
return null;
}
if (attr instanceof RuntimeException) {
throw (RuntimeException) attr;
}
if (attr instanceof Error) {
throw (Error) attr;
}
if (!(attr instanceof WebApplicationContext)) {
throw new IllegalStateException("Root context attribute is not of type WebApplicationContext: " + attr);
}
return (WebApplicationContext) attr;
}
/**
* Find the root WebApplicationContext for this web application, which is
* typically loaded via ContextLoaderListener or ContextLoaderServlet.
*
Will rethrow an exception that happened on root context startup,
* to differentiate between a failed context startup and no context at all.
* @param sc 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;
}
}