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Spring Framework example source code file (RequestContextAwareTag.java)

This example Spring Framework source code file (RequestContextAwareTag.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

exception, exception, http, jsp, jspexception, jspexception, request_context_page_attribute, requestcontext, requestcontext, requestcontextawaretag, runtimeexception, servlet, string, string, tagsupport, throwable, trycatchfinally

The Spring Framework RequestContextAwareTag.java source code

/*
 * Copyright 2002-2006 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.servlet.tags;

import javax.servlet.jsp.JspException;
import javax.servlet.jsp.JspTagException;
import javax.servlet.jsp.tagext.TagSupport;
import javax.servlet.jsp.tagext.TryCatchFinally;

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

import org.springframework.web.servlet.support.JspAwareRequestContext;
import org.springframework.web.servlet.support.RequestContext;

/**
 * Superclass for all tags that require a {@link RequestContext}.
 * 
 * <p>The RequestContext instance provides easy access
 * to current state like the
 * {@link org.springframework.web.context.WebApplicationContext},
 * the {@link java.util.Locale}, the
 * {@link org.springframework.ui.context.Theme}, etc.
 *
 * <p>Mainly intended for
 * {@link org.springframework.web.servlet.DispatcherServlet} requests;
 * will use fallbacks when used outside <code>DispatcherServlet.
 *
 * @author Rod Johnson
 * @author Juergen Hoeller
 * @see org.springframework.web.servlet.support.RequestContext
 * @see org.springframework.web.servlet.DispatcherServlet
 */
public abstract class RequestContextAwareTag extends TagSupport implements TryCatchFinally {

	/** {@link javax.servlet.jsp.PageContext} attribute for page-level
	 * {@link RequestContext} instance.
	 * */
	public static final String REQUEST_CONTEXT_PAGE_ATTRIBUTE =
			"org.springframework.web.servlet.tags.REQUEST_CONTEXT";

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


	private RequestContext requestContext;


	/**
	 * Create and expose the current RequestContext.
	 * Delegates to {@link #doStartTagInternal()} for actual work.
	 * @see #REQUEST_CONTEXT_PAGE_ATTRIBUTE
	 * @see org.springframework.web.servlet.support.JspAwareRequestContext
	 */
	public final int doStartTag() throws JspException {
		this.requestContext = (RequestContext) this.pageContext.getAttribute(REQUEST_CONTEXT_PAGE_ATTRIBUTE);
		try {
			if (this.requestContext == null) {
				this.requestContext = new JspAwareRequestContext(this.pageContext);
				this.pageContext.setAttribute(REQUEST_CONTEXT_PAGE_ATTRIBUTE, this.requestContext);
			}
			return doStartTagInternal();
		}
		catch (JspException ex) {
			logger.error(ex.getMessage(), ex);
			throw ex;
		}
		catch (RuntimeException ex) {
			logger.error(ex.getMessage(), ex);
			throw ex;
		}
		catch (Exception ex) {
			logger.error(ex.getMessage(), ex);
			throw new JspTagException(ex.getMessage());
		}
	}

	/**
	 * Return the current RequestContext.
	 */
	protected final RequestContext getRequestContext() {
		return this.requestContext;
	}

	/**
	 * Called by doStartTag to perform the actual work.
	 * @return same as TagSupport.doStartTag
	 * @throws Exception any exception, any checked one other than
	 * a JspException gets wrapped in a JspException by doStartTag
	 * @see javax.servlet.jsp.tagext.TagSupport#doStartTag
	 */
	protected abstract int doStartTagInternal() throws Exception;


	public void doCatch(Throwable throwable) throws Throwable {
		throw throwable;
	}

	public void doFinally() {
		this.requestContext = null;
	}

}

Other Spring Framework examples (source code examples)

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