org.springframework.web.context.request.RequestContextListener.java Source code

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Here is the source code for org.springframework.web.context.request.RequestContextListener.java

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/*
 * Copyright 2002-2007 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.servlet.ServletRequestEvent;
import javax.servlet.ServletRequestListener;
import javax.servlet.http.HttpServletRequest;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import org.springframework.context.i18n.LocaleContextHolder;

/**
 * Servlet 2.4+ listener that exposes the request to the current thread,
 * through both {@link org.springframework.context.i18n.LocaleContextHolder} and
 * {@link RequestContextHolder}. To be registered as listener in <code>web.xml</code>.
 *
 * <p>Alternatively, Spring's {@link org.springframework.web.filter.RequestContextFilter}
 * and Spring's {@link org.springframework.web.servlet.DispatcherServlet} also expose
 * the same request context to the current thread.
 *
 * <p>This listener is mainly for use with third-party servlets, e.g. the JSF FacesServlet.
 * Within Spring's own web support, DispatcherServlet's processing is perfectly sufficient.
 *
 * @author Juergen Hoeller
 * @since 2.0
 * @see javax.servlet.ServletRequestListener
 * @see org.springframework.context.i18n.LocaleContextHolder
 * @see org.springframework.web.context.request.RequestContextHolder
 * @see org.springframework.web.filter.RequestContextFilter
 * @see org.springframework.web.servlet.DispatcherServlet
 */
public class RequestContextListener implements ServletRequestListener {

    private static final String REQUEST_ATTRIBUTES_ATTRIBUTE = RequestContextListener.class.getName()
            + ".REQUEST_ATTRIBUTES";

    /** Logger available to subclasses */
    protected final Log logger = LogFactory.getLog(getClass());

    public void requestInitialized(ServletRequestEvent requestEvent) {
        if (!(requestEvent.getServletRequest() instanceof HttpServletRequest)) {
            throw new IllegalArgumentException(
                    "Request is not an HttpServletRequest: " + requestEvent.getServletRequest());
        }
        HttpServletRequest request = (HttpServletRequest) requestEvent.getServletRequest();
        ServletRequestAttributes attributes = new ServletRequestAttributes(request);
        request.setAttribute(REQUEST_ATTRIBUTES_ATTRIBUTE, attributes);
        LocaleContextHolder.setLocale(request.getLocale());
        RequestContextHolder.setRequestAttributes(attributes);
        if (logger.isDebugEnabled()) {
            logger.debug("Bound request context to thread: " + request);
        }
    }

    public void requestDestroyed(ServletRequestEvent requestEvent) {
        ServletRequestAttributes attributes = (ServletRequestAttributes) requestEvent.getServletRequest()
                .getAttribute(REQUEST_ATTRIBUTES_ATTRIBUTE);
        ServletRequestAttributes threadAttributes = (ServletRequestAttributes) RequestContextHolder
                .getRequestAttributes();
        if (threadAttributes != null) {
            // We're assumably within the original request thread...
            if (attributes == null) {
                attributes = threadAttributes;
            }
            RequestContextHolder.setRequestAttributes(null);
            LocaleContextHolder.setLocale(null);
        }
        if (attributes != null) {
            attributes.requestCompleted();
            if (logger.isDebugEnabled()) {
                logger.debug("Cleared thread-bound request context: " + requestEvent.getServletRequest());
            }
        }
    }

}