org.apache.commons.digester.plugins.strategies.FinderSetProperties Maven / Gradle / Ivy
/* $Id: FinderSetProperties.java 729125 2008-12-23 21:21:07Z rahul $
*
* 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.
*/
package org.apache.commons.digester.plugins.strategies;
import java.util.Properties;
import org.apache.commons.digester.Digester;
import org.apache.commons.digester.plugins.RuleFinder;
import org.apache.commons.digester.plugins.RuleLoader;
/**
* A rule-finding algorithm which expects the user to specify whether
* "automatic property setting" is desired. If this class discovers that
* this is in fact the case for a declaration, then a RuleLoader is returned
* which, when invoked, adds a single SetPropertiesRule instance to the
* digester.
*
* This allows ordinary JavaBean classes to be used as plugins, and have
* xml attributes be mapped to bean properties of the same name, without
* any custom plugin rules being created for them.
*
* This RuleFinder is typically used as the last RuleFinder, so that
* automatic property setting only occurs if there is no other source of
* custom rules available.
*
* @since 1.6
*/
public class FinderSetProperties extends RuleFinder {
public static String DFLT_PROPS_ATTR = "setprops";
public static String DFLT_FALSEVAL = "false";
private String propsAttr;
private String falseval;
/** See {@link #findLoader}. */
public FinderSetProperties() {
this(DFLT_PROPS_ATTR, DFLT_FALSEVAL);
}
/**
* Create a rule-finder which will arrange for a SetPropertiesRule to
* be defined for each instance of a plugin, so that xml attributes
* map to bean properties.
*
* Param falseval will commonly be the string "false" for config files
* written in English.
*
* @param propsAttr must be non-null.
* @param falseval must be non-null.
*/
public FinderSetProperties(String propsAttr, String falseval) {
this.propsAttr = propsAttr;
this.falseval = falseval;
}
/**
* Returns a RuleLoader unless the properties contain an entry
* with the name matching constructor param propsAttr, and the value
* matching what is in falseval.
*
* If no custom source of rules for a plugin is found, then the user
* almost always wants xml attributes to map to java bean properties,
* so this is the default behaviour unless the user explicitly indicates
* that they do not want a SetPropertiesRule to be provided for
* the plugged-in class.
*
* The returned object (when non-null) will add a SetPropertiesRule to
* the digester whenever its addRules method is invoked.
*/
public RuleLoader findLoader(Digester d, Class pluginClass, Properties p) {
String state = p.getProperty(propsAttr);
if ((state != null) && state.equals(falseval)) {
// user has explicitly disabled automatic setting of properties.
// this is not expected to be common, but allowed.
return null;
}
return new LoaderSetProperties();
}
}