org.openmrs.web.taglib.OpenmrsRequestContextAwareBodyTag.java Source code

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Here is the source code for org.openmrs.web.taglib.OpenmrsRequestContextAwareBodyTag.java

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/**
 * This Source Code Form is subject to the terms of the Mozilla Public License,
 * v. 2.0. If a copy of the MPL was not distributed with this file, You can
 * obtain one at http://mozilla.org/MPL/2.0/. OpenMRS is also distributed under
 * the terms of the Healthcare Disclaimer located at http://openmrs.org/license.
 *
 * Copyright (C) OpenMRS Inc. OpenMRS is a registered trademark and the OpenMRS
 * graphic logo is a trademark of OpenMRS Inc.
 */
package org.openmrs.web.taglib;

import javax.servlet.jsp.JspException;
import javax.servlet.jsp.JspTagException;
import javax.servlet.jsp.JspWriter;
import javax.servlet.jsp.tagext.BodyTagSupport;

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;
import org.springframework.web.servlet.tags.RequestContextAwareTag;

/**
 * Similar to Spring's {@link RequestContextAwareTag}, but intended to support tag body handling on the basis of functionalities,
 * provided by JSTL {@link BodyTagSupport}. Actually, it inherits additional convenience methods including getter methods for the
 * bodyContent property and methods to get at the previous out {@link JspWriter}. May be considered as base class for all tags that
 * require a {@link RequestContext} and aware on processing of tag body content.
 * <p>
 * With use of a <code>RequestContext</code> instance, you can get easy access to current state like the web application context,
 * locale and so on.
 * </p>
 */
public abstract class OpenmrsRequestContextAwareBodyTag extends BodyTagSupport {

    /** */
    private static final long serialVersionUID = 1L;

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

    private RequestContext requestContext;

    /**
     * @see javax.servlet.jsp.tagext.BodyTagSupport#doStartTag()
     */
    @Override
    public final int doStartTag() throws JspException {
        // explicitly tell container that it's need to buffer the tag body content
        return EVAL_BODY_BUFFERED;
    }

    /**
     * After tag body has been evaluated and buffered this creates and exposes the current RequestContext. Delegates to
     * {@link #doEndTagInternal()} for actual work.
     */
    @Override
    public final int doEndTag() throws JspException {
        try {
            // get request content available from pageContext
            this.requestContext = (RequestContext) this.pageContext
                    .getAttribute(RequestContextAwareTag.REQUEST_CONTEXT_PAGE_ATTRIBUTE);
            // if request context is not specified, create empty request context and set it into pageContext
            if (this.requestContext == null) {
                this.requestContext = new JspAwareRequestContext(this.pageContext);
                this.pageContext.setAttribute(RequestContextAwareTag.REQUEST_CONTEXT_PAGE_ATTRIBUTE,
                        this.requestContext);
            }
            // do actual work of this tag
            return doEndTagInternal();
        } 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 doEndTag to perform the actual work.
     * 
     * @return same as BodyTagSupport.doEndTag
     * @throws Exception
     *             any exception, any checked one other than a JspException gets wrapped in a JspException by doEndTag
     * @see javax.servlet.jsp.tagext.TagSupport#doEndTag
     */
    protected abstract int doEndTagInternal() throws Exception;

}