Spring Framework example source code file (RequestContextHolder.java)

This example Spring Framework source code file (RequestContextHolder.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Spring Framework tags/keywords

facesrequestattributesfactory, if, illegalstateexception, illegalstateexception, in, no, request, request, requestattributes, requestattributes, requestcontextholder, requestcontextlistener, threadlocal, threadlocal

The Spring Framework RequestContextHolder.java source code

/*
 * 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.context.request;

import javax.faces.context.FacesContext;

import org.springframework.core.NamedInheritableThreadLocal;
import org.springframework.core.NamedThreadLocal;
import org.springframework.util.ClassUtils;

/**
 * Holder class to expose the web request in the form of a thread-bound
 * {@link RequestAttributes} object.
 *
 * <p>Use {@link RequestContextListener} or
 * {@link org.springframework.web.filter.RequestContextFilter} to expose
 * the current web request. Note that
 * {@link org.springframework.web.servlet.DispatcherServlet} and
 * {@link org.springframework.web.portlet.DispatcherPortlet} already
 * expose the current request by default.
 *
 * @author Juergen Hoeller
 * @author Rod Johnson
 * @since 2.0
 * @see RequestContextListener
 * @see org.springframework.web.filter.RequestContextFilter
 * @see org.springframework.web.servlet.DispatcherServlet
 * @see org.springframework.web.portlet.DispatcherPortlet
 */
public abstract class RequestContextHolder  {
	
	private static final boolean jsfPresent = ClassUtils.isPresent("javax.faces.context.FacesContext");

	private static final ThreadLocal requestAttributesHolder = new NamedThreadLocal("Request attributes");

	private static final ThreadLocal inheritableRequestAttributesHolder =
			new NamedInheritableThreadLocal("Request context");


	/**
	 * Reset the RequestAttributes for the current thread.
	 */
	public static void resetRequestAttributes() {
		requestAttributesHolder.set(null);
		inheritableRequestAttributesHolder.set(null);
	}

	/**
	 * Bind the given RequestAttributes to the current thread,
	 * <i>not exposing it as inheritable for child threads.
	 * @param attributes the RequestAttributes to expose
	 * @see #setRequestAttributes(RequestAttributes, boolean)
	 */
	public static void setRequestAttributes(RequestAttributes attributes) {
		setRequestAttributes(attributes, false);
	}

	/**
	 * Bind the given RequestAttributes to the current thread.
	 * @param attributes the RequestAttributes to expose
	 * @param inheritable whether to expose the RequestAttributes as inheritable
	 * for child threads (using an {@link java.lang.InheritableThreadLocal})
	 */
	public static void setRequestAttributes(RequestAttributes attributes, boolean inheritable) {
		if (inheritable) {
			inheritableRequestAttributesHolder.set(attributes);
			requestAttributesHolder.set(null);
		}
		else {
			requestAttributesHolder.set(attributes);
			inheritableRequestAttributesHolder.set(null);
		}
	}

	/**
	 * Return the RequestAttributes currently bound to the thread.
	 * @return the RequestAttributes currently bound to the thread,
	 * or <code>null if none bound
	 */
	public static RequestAttributes getRequestAttributes() {
		RequestAttributes attributes = (RequestAttributes) requestAttributesHolder.get();
		if (attributes == null) {
			attributes = (RequestAttributes) inheritableRequestAttributesHolder.get();
		}
		return attributes;
	}

	/**
	 * Return the RequestAttributes currently bound to the thread.
	 * <p>Exposes the previously bound RequestAttributes instance, if any.
	 * Falls back to the current JSF FacesContext, if any.
	 * @return the RequestAttributes currently bound to the thread
	 * @throws IllegalStateException if no RequestAttributes object
	 * is bound to the current thread
	 * @see #setRequestAttributes
	 * @see ServletRequestAttributes
	 * @see FacesRequestAttributes
	 * @see javax.faces.context.FacesContext#getCurrentInstance()
	 */
	public static RequestAttributes currentRequestAttributes() throws IllegalStateException {
		RequestAttributes attributes = getRequestAttributes();
		if (attributes == null) {
			if (jsfPresent) {
				attributes = FacesRequestAttributesFactory.getFacesRequestAttributes();
			}
			if (attributes == null) {
				throw new IllegalStateException("No thread-bound request found: " +
						"Are you referring to request attributes outside of an actual web request, " +
						"or processing a request outside of the originally receiving thread? " +
						"If you are actually operating within a web request and still receive this message, " +
						"your code is probably running outside of DispatcherServlet/DispatcherPortlet: " +
						"In this case, use RequestContextListener or RequestContextFilter to expose the current request.");
			}
		}
		return attributes;
	}


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

		public static RequestAttributes getFacesRequestAttributes() {
			FacesContext facesContext = FacesContext.getCurrentInstance();
			return (facesContext != null ? new FacesRequestAttributes(facesContext) : null);
		}
	}

}