001/* 
002    Licensed to the Apache Software Foundation (ASF) under one
003    or more contributor license agreements.  See the NOTICE file
004    distributed with this work for additional information
005    regarding copyright ownership.  The ASF licenses this file
006    to you under the Apache License, Version 2.0 (the
007    "License"); you may not use this file except in compliance
008    with the License.  You may obtain a copy of the License at
009
010       http://www.apache.org/licenses/LICENSE-2.0
011
012    Unless required by applicable law or agreed to in writing,
013    software distributed under the License is distributed on an
014    "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
015    KIND, either express or implied.  See the License for the
016    specific language governing permissions and limitations
017    under the License.  
018 */
019package org.apache.wiki.tags;
020
021import org.apache.log4j.Logger;
022import org.apache.wiki.api.core.Context;
023import org.apache.wiki.util.TextUtil;
024
025import javax.servlet.jsp.JspException;
026import javax.servlet.jsp.PageContext;
027import javax.servlet.jsp.tagext.TagSupport;
028import javax.servlet.jsp.tagext.TryCatchFinally;
029
030
031/**
032 *  Base class for JSPWiki tags.  You do not necessarily have to derive from this class, since this does some initialization.
033 *  <P>
034 *  This tag is only useful if you're having an "empty" tag, with no body content.
035 *
036 *  @since 2.0
037 */
038public abstract class WikiTagBase extends TagSupport implements TryCatchFinally {
039
040    private static final long serialVersionUID = -1409836349293777141L;
041    private static final Logger log = Logger.getLogger( WikiTagBase.class );
042
043    protected Context m_wikiContext;
044
045    /**
046     * This method calls the parent setPageContext() but it also provides a way for a tag to initialize itself before
047     * any of the setXXX() methods are called.
048     */
049    public void setPageContext( final PageContext arg0 ) {
050        super.setPageContext( arg0 );
051        initTag();
052    }
053
054    /**
055     *  This method is called when the tag is encountered within a new request, but before the setXXX() methods are called.
056     *  The default implementation does nothing.
057     *  @since 2.3.92
058     */
059    public void initTag() {
060        m_wikiContext = null;
061    }
062    
063    public int doStartTag() throws JspException {
064        try {
065            m_wikiContext = ( Context )pageContext.getAttribute( Context.ATTR_CONTEXT, PageContext.REQUEST_SCOPE );
066            if( m_wikiContext == null ) {
067                throw new JspException("WikiContext may not be NULL - serious internal problem!");
068            }
069
070            return doWikiStartTag();
071        } catch( final Exception e ) {
072            log.error( "Tag failed", e );
073            throw new JspException( "Tag failed, check logs: "+e.getMessage() );
074        }
075    }
076
077    /**
078     *  This method is allowed to do pretty much whatever he wants.
079     *  We then catch all mistakes.
080     */
081    public abstract int doWikiStartTag() throws Exception;
082
083    public int doEndTag() throws JspException {
084        return EVAL_PAGE;
085    }
086
087    public void doCatch( final Throwable th ) throws Throwable {
088        log.error( th.getMessage(), th );
089    }
090
091    public void doFinally()
092    {
093        m_wikiContext = null;
094    }
095
096    public void setId( final String id)
097    {
098        super.setId( TextUtil.replaceEntities( id ) );
099    }
100
101}