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package org.apache.velocity.app.event.implement;
/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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.
*/
import org.apache.velocity.app.event.ReferenceInsertionEventHandler;
import org.apache.velocity.context.Context;
import org.apache.velocity.runtime.RuntimeServices;
import org.apache.velocity.util.RuntimeServicesAware;
import org.apache.commons.lang3.StringUtils;
import org.slf4j.Logger;
import java.util.regex.PatternSyntaxException;
/**
* Base class for escaping references. To use it, override the following methods:
* <DL>
* <DT><code>String escape(String text)</code></DT>
* <DD>escape the provided text</DD>
* <DT><code>String getMatchAttribute()</code></DT>
* <DD>retrieve the configuration attribute used to match references (see below)</DD>
* </DL>
*
* <P>By default, all references are escaped. However, by setting the match attribute
* in the configuration file to a regular expression, users can specify which references
* to escape. For example the following configuration property tells the EscapeSqlReference
* event handler to only escape references that start with "sql".
* (e.g. <code>$sql</code>, <code>$sql.toString(),</code>, etc).
*
* <PRE>
* <CODE>eventhandler.escape.sql.match = sql.*</CODE>
* </PRE>
*
* Regular expressions should follow the format used by the Java language. More info in the
* <a href="http://docs.oracle.com/javase/7/docs/api/java/util/regex/Pattern.html">Pattern class documentation</a>.
*
* @author <a href="mailto:wglass@forio.com">Will Glass-Husain </a>
* @version $Id$
* @since 1.5
*/
public abstract class EscapeReference implements ReferenceInsertionEventHandler,RuntimeServicesAware {
private RuntimeServices rs;
private String matchRegExp = null;
protected Logger log;
/**
* Escape the given text. Override this in a subclass to do the actual
* escaping.
*
* @param text the text to escape
* @return the escaped text
*/
protected abstract String escape(Object text);
/**
* Specify the configuration attribute that specifies the
* regular expression. Ideally should be in a form
* <pre><code>eventhandler.escape.XYZ.match</code></pre>
*
* <p>where <code>XYZ</code> is the type of escaping being done.
* @return configuration attribute
*/
protected abstract String getMatchAttribute();
/**
* Escape the provided text if it matches the configured regular expression.
*
* @param reference
* @param value
* @return Escaped text.
*/
@Override
public Object referenceInsert(Context context, String reference, Object value)
{
if(value == null)
{
return value;
}
if (matchRegExp == null)
{
return escape(value);
}
else if (reference.matches(matchRegExp))
{
return escape(value);
}
else
{
return value;
}
}
/**
* Called automatically when event cartridge is initialized.
*
* @param rs instance of RuntimeServices
*/
@Override
public void setRuntimeServices(RuntimeServices rs)
{
this.rs = rs;
log = rs.getLog("event");
// Get the regular expression pattern.
matchRegExp = StringUtils.trim(rs.getString(getMatchAttribute()));
if (org.apache.commons.lang3.StringUtils.isEmpty(matchRegExp))
{
matchRegExp = null;
}
// Test the regular expression for a well formed pattern
if (matchRegExp != null)
{
try
{
"".matches(matchRegExp);
}
catch (PatternSyntaxException E)
{
log.error("Invalid regular expression '{}'. No escaping will be performed.",
matchRegExp, E);
matchRegExp = null;
}
}
}
/**
* Retrieve a reference to RuntimeServices. Use this for checking additional
* configuration properties.
*
* @return The current runtime services object.
*/
protected RuntimeServices getRuntimeServices()
{
return rs;
}
}
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