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 */
019 package org.apache.wiki.tags;
020
021 import javax.servlet.jsp.JspException;
022 import javax.servlet.jsp.PageContext;
023 import javax.servlet.jsp.tagext.TagSupport;
024 import javax.servlet.jsp.tagext.TryCatchFinally;
025
026 import org.apache.log4j.Logger;
027
028 import org.apache.wiki.WikiContext;
029 import org.apache.wiki.util.TextUtil;
030
031 /**
032 * Base class for JSPWiki tags. You do not necessarily have
033 * to derive from this class, since this does some initialization.
034 * <P>
035 * This tag is only useful if you're having an "empty" tag, with
036 * no body content.
037 *
038 * @since 2.0
039 */
040 public abstract class WikiTagBase
041 extends TagSupport
042 implements TryCatchFinally
043 {
044 private static final long serialVersionUID = -1409836349293777141L;
045
046 public static final String ATTR_CONTEXT = "jspwiki.context";
047
048 private static final Logger log = Logger.getLogger( WikiTagBase.class );
049
050 protected WikiContext m_wikiContext;
051
052 /**
053 * This method calls the parent setPageContext() but it also
054 * provides a way for a tag to initialize itself before
055 * any of the setXXX() methods are called.
056 */
057 public void setPageContext(PageContext arg0)
058 {
059 super.setPageContext(arg0);
060
061 initTag();
062 }
063
064 /**
065 * This method is called when the tag is encountered within a new request,
066 * but before the setXXX() methods are called.
067 * The default implementation does nothing.
068 * @since 2.3.92
069 */
070 public void initTag()
071 {
072 m_wikiContext = null;
073 return;
074 }
075
076 public int doStartTag()
077 throws JspException
078 {
079 try
080 {
081 m_wikiContext = (WikiContext) pageContext.getAttribute( ATTR_CONTEXT,
082 PageContext.REQUEST_SCOPE );
083
084 if( m_wikiContext == null )
085 {
086 throw new JspException("WikiContext may not be NULL - serious internal problem!");
087 }
088
089 return doWikiStartTag();
090 }
091 catch( Exception e )
092 {
093 log.error( "Tag failed", e );
094 throw new JspException( "Tag failed, check logs: "+e.getMessage() );
095 }
096 }
097
098 /**
099 * This method is allowed to do pretty much whatever he wants.
100 * We then catch all mistakes.
101 */
102 public abstract int doWikiStartTag() throws Exception;
103
104 public int doEndTag()
105 throws JspException
106 {
107 return EVAL_PAGE;
108 }
109
110 public void doCatch( Throwable th ) throws Throwable
111 {
112 log.error( th.getMessage(), th );
113 }
114
115 public void doFinally()
116 {
117 m_wikiContext = null;
118 }
119
120 public void setId(String id)
121 {
122 super.setId( TextUtil.replaceEntities( id ) );
123 }
124
125 }