The Tomcat SetPropertiesRule.java source code
/* $Id: SetPropertiesRule.java 565464 2007-08-13 18:13:47Z remm $
*
* 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.tomcat.util.digester;
import org.apache.tomcat.util.IntrospectionUtils;
import org.xml.sax.Attributes;
/**
* <p>Rule implementation that sets properties on the object at the top of the
* stack, based on attributes with corresponding names.</p>
*
* <p>This rule supports custom mapping of attribute names to property names.
* The default mapping for particular attributes can be overridden by using
* {@link #SetPropertiesRule(String[] attributeNames, String[] propertyNames)}.
* This allows attributes to be mapped to properties with different names.
* Certain attributes can also be marked to be ignored.</p>
*/
public class SetPropertiesRule extends Rule {
// ----------------------------------------------------------- Constructors
/**
* Default constructor sets only the the associated Digester.
*
* @param digester The digester with which this rule is associated
*
* @deprecated The digester instance is now set in the {@link Digester#addRule} method.
* Use {@link #SetPropertiesRule()} instead.
*/
public SetPropertiesRule(Digester digester) {
this();
}
/**
* Base constructor.
*/
public SetPropertiesRule() {
// nothing to set up
}
/**
* <p>Convenience constructor overrides the mapping for just one property.
*
* <p>For details about how this works, see
* {@link #SetPropertiesRule(String[] attributeNames, String[] propertyNames)}.</p>
*
* @param attributeName map this attribute
* @param propertyName to a property with this name
*/
public SetPropertiesRule(String attributeName, String propertyName) {
attributeNames = new String[1];
attributeNames[0] = attributeName;
propertyNames = new String[1];
propertyNames[0] = propertyName;
}
/**
* <p>Constructor allows attribute->property mapping to be overriden.
*
* <p>Two arrays are passed in.
* One contains the attribute names and the other the property names.
* The attribute name / property name pairs are match by position
* In order words, the first string in the attribute name list matches
* to the first string in the property name list and so on.</p>
*
* <p>If a property name is null or the attribute name has no matching
* property name, then this indicates that the attibute should be ignored.</p>
*
* <h5>Example One
* <p> The following constructs a rule that maps the alt-city
* attribute to the <code>city property and the alt-state
* to the <code>state property.
* All other attributes are mapped as usual using exact name matching.
* <code> * SetPropertiesRule(
* new String[] {"alt-city", "alt-state"},
* new String[] {"city", "state"});
* </pre>
*
* <h5>Example Two
* <p> The following constructs a rule that maps the class
* attribute to the <code>className property.
* The attribute <code>ignore-me is not mapped.
* All other attributes are mapped as usual using exact name matching.
* <code> * SetPropertiesRule(
* new String[] {"class", "ignore-me"},
* new String[] {"className"});
* </pre>
*
* @param attributeNames names of attributes to map
* @param propertyNames names of properties mapped to
*/
public SetPropertiesRule(String[] attributeNames, String[] propertyNames) {
// create local copies
this.attributeNames = new String[attributeNames.length];
for (int i=0, size=attributeNames.length; i<size; i++) {
this.attributeNames[i] = attributeNames[i];
}
this.propertyNames = new String[propertyNames.length];
for (int i=0, size=propertyNames.length; i<size; i++) {
this.propertyNames[i] = propertyNames[i];
}
}
// ----------------------------------------------------- Instance Variables
/**
* Attribute names used to override natural attribute->property mapping
*/
private String [] attributeNames;
/**
* Property names used to override natural attribute->property mapping
*/
private String [] propertyNames;
// --------------------------------------------------------- Public Methods
/**
* Process the beginning of this element.
*
* @param attributes The attribute list of this element
*/
public void begin(Attributes attributes) throws Exception {
// Populate the corresponding properties of the top object
Object top = digester.peek();
if (digester.log.isDebugEnabled()) {
if (top != null) {
digester.log.debug("[SetPropertiesRule]{" + digester.match +
"} Set " + top.getClass().getName() +
" properties");
} else {
digester.log.debug("[SetPropertiesRule]{" + digester.match +
"} Set NULL properties");
}
}
// set up variables for custom names mappings
int attNamesLength = 0;
if (attributeNames != null) {
attNamesLength = attributeNames.length;
}
int propNamesLength = 0;
if (propertyNames != null) {
propNamesLength = propertyNames.length;
}
for (int i = 0; i < attributes.getLength(); i++) {
String name = attributes.getLocalName(i);
if ("".equals(name)) {
name = attributes.getQName(i);
}
String value = attributes.getValue(i);
// we'll now check for custom mappings
for (int n = 0; n<attNamesLength; n++) {
if (name.equals(attributeNames[n])) {
if (n < propNamesLength) {
// set this to value from list
name = propertyNames[n];
} else {
// set name to null
// we'll check for this later
name = null;
}
break;
}
}
if (digester.log.isDebugEnabled()) {
digester.log.debug("[SetPropertiesRule]{" + digester.match +
"} Setting property '" + name + "' to '" +
value + "'");
}
if (!digester.isFakeAttribute(top, name)
&& !IntrospectionUtils.setProperty(top, name, value)
&& digester.getRulesValidation()) {
digester.log.warn("[SetPropertiesRule]{" + digester.match +
"} Setting property '" + name + "' to '" +
value + "' did not find a matching property.");
}
}
}
/**
* <p>Add an additional attribute name to property name mapping.
* This is intended to be used from the xml rules.
*/
public void addAlias(String attributeName, String propertyName) {
// this is a bit tricky.
// we'll need to resize the array.
// probably should be synchronized but digester's not thread safe anyway
if (attributeNames == null) {
attributeNames = new String[1];
attributeNames[0] = attributeName;
propertyNames = new String[1];
propertyNames[0] = propertyName;
} else {
int length = attributeNames.length;
String [] tempAttributes = new String[length + 1];
for (int i=0; i<length; i++) {
tempAttributes[i] = attributeNames[i];
}
tempAttributes[length] = attributeName;
String [] tempProperties = new String[length + 1];
for (int i=0; i<length && i< propertyNames.length; i++) {
tempProperties[i] = propertyNames[i];
}
tempProperties[length] = propertyName;
propertyNames = tempProperties;
attributeNames = tempAttributes;
}
}
/**
* Render a printable version of this Rule.
*/
public String toString() {
StringBuffer sb = new StringBuffer("SetPropertiesRule[");
sb.append("]");
return (sb.toString());
}
}
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