src/java/org/apache/commons/digester/SetNestedPropertiesRule.java - commons-digester - Git at Google

 /* $Id: SetNestedPropertiesRule.java,v 1.8 2004/05/10 06:52:50 skitching Exp $
  *
  * Copyright 2003-2004 The Apache Software Foundation.
  *
  * Licensed 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;


 import java.util.List;
 import java.util.LinkedList;
 import java.util.ArrayList;
 import java.util.Iterator;
 import java.util.ListIterator;
 import java.util.HashMap;
 import java.beans.PropertyDescriptor;

 import org.apache.commons.beanutils.BeanUtils;
 import org.apache.commons.beanutils.DynaBean;
 import org.apache.commons.beanutils.DynaProperty;
 import org.apache.commons.beanutils.PropertyUtils;

 import org.xml.sax.Attributes;

 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;


 /**
  * <p>Rule implementation that sets properties on the object at the top of the
  * stack, based on child elements with names matching properties on that
  * object.</p>
  *
  * <p>Example input that can be processed by this rule:</p>
  * <pre>
  *   [widget]
  *    [height]7[/height]
  *    [width]8[/width]
  *    [label]Hello, world[/label]
  *   [/widget]
  * </pre>
  *
  * <p>This rule supports custom mapping of attribute names to property names.
  * The default mapping for particular attributes can be overridden by using
  * {@link #SetNestedPropertiesRule(String[] elementNames,
  *                                 String[] propertyNames)}.
  * This allows child elements to be mapped to properties with different names.
  * Certain elements can also be marked to be ignored.</p>
  *
  * <p>A very similar effect can be achieved using a combination of the
  * <code>BeanPropertySetterRule</code> and the <code>ExtendedBaseRules</code>
  * rules manager; this <code>Rule</code>, however, works fine with the default
  * <code>RulesBase</code> rules manager.</p>
  *
  * <p><b>Implementation Notes</b></p>
  *
  * <p>This class works by creating its own simple Rules implementation. When
  * begin is invoked on this rule, the digester's current rules object is
  * replaced by a custom one. When end is invoked for this rule, the original
  * rules object is restored. The digester rules objects therefore behave in
  * a stack-like manner.</p>
  *
  * <p>For each child element encountered, the custom Rules implementation
  * ensures that a special AnyChildRule instance is included in the matches
  * returned to the digester, and it is this rule instance that is responsible
  * for setting the appropriate property on the target object (if such a property
  * exists). The effect is therefore like a "trailing wildcard pattern". The
  * custom Rules implementation also returns the matches provided by the
  * underlying Rules implementation for the same pattern, so other rules
  * are not "disabled" during processing of a SetNestedPropertiesRule.</p>
  *
  * @since 1.6
  */

 public class SetNestedPropertiesRule extends Rule {

     /**
      * Dummy object that can be placed in collections to indicate an
      * ignored property when null cannot be used for that purpose.
      */
     private static final String PROP_IGNORE = "ignore-me";

     private Log log = null;

     private AnyChildRule anyChildRule = new AnyChildRule();
     private AnyChildRules newRules = new AnyChildRules(anyChildRule);
     private Rules oldRules = null;

     private boolean trimData = true;
     private boolean allowUnknownChildElements = false;

     private HashMap elementNames = new HashMap();

     // ----------------------------------------------------------- Constructors

     /**
      * Base constructor.
      */
     public SetNestedPropertiesRule() {
         // nothing to set up
     }

     /**
      * <p>Convenience constructor overrides the mapping for just one property.</p>
      *
      * <p>For details about how this works, see
      * {@link #SetNestedPropertiesRule(String[] elementNames,
      * String[] propertyNames)}.</p>
      *
      * @param elementName map the child element to match
      * @param propertyName to a property with this name
      */
     public SetNestedPropertiesRule(String elementName, String propertyName) {
         elementNames.put(elementName, propertyName);
     }

     /**
      * <p>Constructor allows element->property mapping to be overriden.</p>
      *
      * <p>Two arrays are passed in.
      * One contains the element names and the other the property names.
      * The element name / property name pairs are match by position
      * In order words, the first string in the element 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 element name has no matching
      * property name, then this indicates that the element should be ignored.</p>
      *
      * <h5>Example One</h5>
      * <p> The following constructs a rule that maps the <code>alt-city</code>
      * element to the <code>city</code> property and the <code>alt-state</code>
      * to the <code>state</code> property.
      * All other child elements are mapped as usual using exact name matching.
      * <code><pre>
      *      SetNestedPropertiesRule(
      *                new String[] {"alt-city", "alt-state"},
      *                new String[] {"city", "state"});
      * </pre></code>
      *
      * <h5>Example Two</h5>
      * <p> The following constructs a rule that maps the <code>class</code>
      * element to the <code>className</code> property.
      * The element <code>ignore-me</code> is not mapped.
      * All other elements are mapped as usual using exact name matching.
      * <code><pre>
      *      SetPropertiesRule(
      *                new String[] {"class", "ignore-me"},
      *                new String[] {"className"});
      * </pre></code>
      *
      * @param elementNames names of elements to map
      * @param propertyNames names of properties mapped to
      */
     public SetNestedPropertiesRule(String[] elementNames, String[] propertyNames) {
         for (int i=0, size=elementNames.length; i<size; i++) {
             String propName = null;
             if (i < propertyNames.length) {
                 propName = propertyNames[i];
             }

             if (propName == null) {
                 this.elementNames.put(elementNames[i], PROP_IGNORE);
             }
             else {
                 this.elementNames.put(elementNames[i], propName);
             }
         }
     }

     // --------------------------------------------------------- Public Methods

     /** Invoked when rule is added to digester. */
     public void setDigester(Digester digester) {
         super.setDigester(digester);
         log = digester.getLogger();
         anyChildRule.setDigester(digester);
     }

     /**
      * When set to true, any text within child elements will have leading
      * and trailing whitespace removed before assignment to the target
      * object. The default value for this attribute is true.
      */
     public void setTrimData(boolean trimData) {
         this.trimData = trimData;
     }

     /** See {@link #setTrimData}. */
      public boolean getTrimData() {
         return trimData;
     }

     /**
      * When set to true, any child element for which there is no
      * corresponding object property will cause an error to be reported.
      * The default value of this attribute is false (not allowed).
      */
     public void setAllowUnknownChildElements(boolean allowUnknownChildElements) {
         this.allowUnknownChildElements = allowUnknownChildElements;
     }

     /** See {@link #setAllowUnknownChildElements}. */
      public boolean getAllowUnknownChildElements() {
         return allowUnknownChildElements;
     }

     /**
      * Process the beginning of this element.
      *
      * @param namespace is the namespace this attribute is in, or null
      * @param name is the name of the current xml element
      * @param attributes is the attribute list of this element
      */
     public void begin(String namespace, String name, Attributes attributes)
                       throws Exception {
         oldRules = digester.getRules();
         newRules.init(digester.getMatch()+"/", oldRules);
         digester.setRules(newRules);
     }

     /**
      * This is only invoked after all child elements have been processed,
      * so we can remove the custom Rules object that does the
      * child-element-matching.
      */
     public void body(String bodyText) throws Exception {
         digester.setRules(oldRules);
     }

     /**
      * <p>Add an additional element name to property name mapping.
      * This is intended to be used from the xml rules.
      */
     public void addAlias(String elementName, String propertyName) {
         if (propertyName == null) {
             elementNames.put(elementName, PROP_IGNORE);
         }
         else {
             elementNames.put(elementName, propertyName);
         }
     }

     /**
      * Render a printable version of this Rule.
      */
     public String toString() {

         return ("SetNestedPropertiesRule");
     }

     //----------------------------------------- local classes

     /** Private Rules implementation */
     private class AnyChildRules implements Rules {
         private String matchPrefix = null;
         private Rules decoratedRules = null;

         private ArrayList rules = new ArrayList(1);
         private AnyChildRule rule;

         public AnyChildRules(AnyChildRule rule) {
             this.rule = rule;
             rules.add(rule);
         }

         public Digester getDigester() { return null; }
         public void setDigester(Digester digester) {}
         public String getNamespaceURI() {return null;}
         public void setNamespaceURI(String namespaceURI) {}
         public void add(String pattern, Rule rule) {}
         public void clear() {}

         public List match(String matchPath) {
             return match(null,matchPath);
         }

         public List match(String namespaceURI, String matchPath) {
             List match = decoratedRules.match(namespaceURI, matchPath);

             if ((matchPath.startsWith(matchPrefix)) &&
                 (matchPath.indexOf('/', matchPrefix.length()) == -1)) {

                 // The current element is a direct child of the element
                 // specified in the init method, so include it as the
                 // first rule in the matches list. The way that
                 // SetNestedPropertiesRule is used, it is in fact very
                 // likely to be the only match, so we optimise that
                 // solution by keeping a list with only the AnyChildRule
                 // instance in it.

                 if ((match == null || match.size()==0)) {
                     return rules;
                 }
                 else {
                     // it might not be safe to modify the returned list,
                     // so clone it first.
                     LinkedList newMatch = new LinkedList(match);
                     //newMatch.addFirst(rule);
                     newMatch.addLast(rule);
                     return newMatch;
                 }
             }
             else {
                 return match;
             }
         }

         public List rules() {
             // This is not actually expected to be called.
             throw new RuntimeException(
                 "AnyChildRules.rules not implemented.");
         }

         public void init(String prefix, Rules rules) {
             matchPrefix = prefix;
             decoratedRules = rules;
         }
     }

     private class AnyChildRule extends Rule {
         private String currChildNamespaceURI = null;
         private String currChildElementName = null;

         public void begin(String namespaceURI, String name,
                               Attributes attributes) throws Exception {

             currChildNamespaceURI = namespaceURI;
             currChildElementName = name;
         }

         public void body(String value) throws Exception {
             boolean debug = log.isDebugEnabled();

             String propName = (String) elementNames.get(currChildElementName);
             if (propName == PROP_IGNORE) {
                 // note: above deliberately tests for IDENTITY, not EQUALITY
                 return;
             }
             if (propName == null) {
                 propName = currChildElementName;
             }

             if (digester.log.isDebugEnabled()) {
                 digester.log.debug("[SetNestedPropertiesRule]{" + digester.match +
                         "} Setting property '" + propName + "' to '" +
                         value + "'");
             }

             // Populate the corresponding properties of the top object
             Object top = digester.peek();
             if (digester.log.isDebugEnabled()) {
                 if (top != null) {
                     digester.log.debug("[SetNestedPropertiesRule]{" + digester.match +
                                        "} Set " + top.getClass().getName() +
                                        " properties");
                 } else {
                     digester.log.debug("[SetPropertiesRule]{" + digester.match +
                                        "} Set NULL properties");
                 }
             }

             if (trimData) {
                 value = value.trim();
             }

             if (!allowUnknownChildElements) {
                 // Force an exception if the property does not exist
                 // (BeanUtils.setProperty() silently returns in this case)
                 if (top instanceof DynaBean) {
                     DynaProperty desc =
                         ((DynaBean) top).getDynaClass().getDynaProperty(propName);
                     if (desc == null) {
                         throw new NoSuchMethodException
                             ("Bean has no property named " + propName);
                     }
                 } else /* this is a standard JavaBean */ {
                     PropertyDescriptor desc =
                         PropertyUtils.getPropertyDescriptor(top, propName);
                     if (desc == null) {
                         throw new NoSuchMethodException
                             ("Bean has no property named " + propName);
                     }
                 }
             }

             BeanUtils.setProperty(top, propName, value);
         }

         public void end(String namespace, String name) throws Exception {
             currChildElementName = null;
         }
     }
 }
	/* $Id: SetNestedPropertiesRule.java,v 1.8 2004/05/10 06:52:50 skitching Exp $
	*
	* Copyright 2003-2004 The Apache Software Foundation.
	*
	* Licensed 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;


	import java.util.List;
	import java.util.LinkedList;
	import java.util.ArrayList;
	import java.util.Iterator;
	import java.util.ListIterator;
	import java.util.HashMap;
	import java.beans.PropertyDescriptor;

	import org.apache.commons.beanutils.BeanUtils;
	import org.apache.commons.beanutils.DynaBean;
	import org.apache.commons.beanutils.DynaProperty;
	import org.apache.commons.beanutils.PropertyUtils;

	import org.xml.sax.Attributes;

	import org.apache.commons.logging.Log;
	import org.apache.commons.logging.LogFactory;


	/**
	* <p>Rule implementation that sets properties on the object at the top of the
	* stack, based on child elements with names matching properties on that
	* object.</p>
	*
	* <p>Example input that can be processed by this rule:</p>
	* <pre>
	* [widget]
	* [height]7[/height]
	* [width]8[/width]
	* [label]Hello, world[/label]
	* [/widget]
	* </pre>
	*
	* <p>This rule supports custom mapping of attribute names to property names.
	* The default mapping for particular attributes can be overridden by using
	* {@link #SetNestedPropertiesRule(String[] elementNames,
	* String[] propertyNames)}.
	* This allows child elements to be mapped to properties with different names.
	* Certain elements can also be marked to be ignored.</p>
	*
	* <p>A very similar effect can be achieved using a combination of the
	* <code>BeanPropertySetterRule</code> and the <code>ExtendedBaseRules</code>
	* rules manager; this <code>Rule</code>, however, works fine with the default
	* <code>RulesBase</code> rules manager.</p>
	*
	* <p><b>Implementation Notes</b></p>
	*
	* <p>This class works by creating its own simple Rules implementation. When
	* begin is invoked on this rule, the digester's current rules object is
	* replaced by a custom one. When end is invoked for this rule, the original
	* rules object is restored. The digester rules objects therefore behave in
	* a stack-like manner.</p>
	*
	* <p>For each child element encountered, the custom Rules implementation
	* ensures that a special AnyChildRule instance is included in the matches
	* returned to the digester, and it is this rule instance that is responsible
	* for setting the appropriate property on the target object (if such a property
	* exists). The effect is therefore like a "trailing wildcard pattern". The
	* custom Rules implementation also returns the matches provided by the
	* underlying Rules implementation for the same pattern, so other rules
	* are not "disabled" during processing of a SetNestedPropertiesRule.</p>
	*
	* @since 1.6
	*/

	public class SetNestedPropertiesRule extends Rule {

	/**
	* Dummy object that can be placed in collections to indicate an
	* ignored property when null cannot be used for that purpose.
	*/
	private static final String PROP_IGNORE = "ignore-me";

	private Log log = null;

	private AnyChildRule anyChildRule = new AnyChildRule();
	private AnyChildRules newRules = new AnyChildRules(anyChildRule);
	private Rules oldRules = null;

	private boolean trimData = true;
	private boolean allowUnknownChildElements = false;

	private HashMap elementNames = new HashMap();

	// ----------------------------------------------------------- Constructors

	/**
	* Base constructor.
	*/
	public SetNestedPropertiesRule() {
	// nothing to set up
	}

	/**
	* <p>Convenience constructor overrides the mapping for just one property.</p>
	*
	* <p>For details about how this works, see
	* {@link #SetNestedPropertiesRule(String[] elementNames,
	* String[] propertyNames)}.</p>
	*
	* @param elementName map the child element to match
	* @param propertyName to a property with this name
	*/
	public SetNestedPropertiesRule(String elementName, String propertyName) {
	elementNames.put(elementName, propertyName);
	}

	/**
	* <p>Constructor allows element->property mapping to be overriden.</p>
	*
	* <p>Two arrays are passed in.
	* One contains the element names and the other the property names.
	* The element name / property name pairs are match by position
	* In order words, the first string in the element 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 element name has no matching
	* property name, then this indicates that the element should be ignored.</p>
	*
	* <h5>Example One</h5>
	* <p> The following constructs a rule that maps the <code>alt-city</code>
	* element to the <code>city</code> property and the <code>alt-state</code>
	* to the <code>state</code> property.
	* All other child elements are mapped as usual using exact name matching.
	* <code><pre>
	* SetNestedPropertiesRule(
	* new String[] {"alt-city", "alt-state"},
	* new String[] {"city", "state"});
	* </pre></code>
	*
	* <h5>Example Two</h5>
	* <p> The following constructs a rule that maps the <code>class</code>
	* element to the <code>className</code> property.
	* The element <code>ignore-me</code> is not mapped.
	* All other elements are mapped as usual using exact name matching.
	* <code><pre>
	* SetPropertiesRule(
	* new String[] {"class", "ignore-me"},
	* new String[] {"className"});
	* </pre></code>
	*
	* @param elementNames names of elements to map
	* @param propertyNames names of properties mapped to
	*/
	public SetNestedPropertiesRule(String[] elementNames, String[] propertyNames) {
	for (int i=0, size=elementNames.length; i<size; i++) {
	String propName = null;
	if (i < propertyNames.length) {
	propName = propertyNames[i];
	}

	if (propName == null) {
	this.elementNames.put(elementNames[i], PROP_IGNORE);
	}
	else {
	this.elementNames.put(elementNames[i], propName);
	}
	}
	}

	// --------------------------------------------------------- Public Methods

	/** Invoked when rule is added to digester. */
	public void setDigester(Digester digester) {
	super.setDigester(digester);
	log = digester.getLogger();
	anyChildRule.setDigester(digester);
	}

	/**
	* When set to true, any text within child elements will have leading
	* and trailing whitespace removed before assignment to the target
	* object. The default value for this attribute is true.
	*/
	public void setTrimData(boolean trimData) {
	this.trimData = trimData;
	}

	/** See {@link #setTrimData}. */
	public boolean getTrimData() {
	return trimData;
	}

	/**
	* When set to true, any child element for which there is no
	* corresponding object property will cause an error to be reported.
	* The default value of this attribute is false (not allowed).
	*/
	public void setAllowUnknownChildElements(boolean allowUnknownChildElements) {
	this.allowUnknownChildElements = allowUnknownChildElements;
	}

	/** See {@link #setAllowUnknownChildElements}. */
	public boolean getAllowUnknownChildElements() {
	return allowUnknownChildElements;
	}

	/**
	* Process the beginning of this element.
	*
	* @param namespace is the namespace this attribute is in, or null
	* @param name is the name of the current xml element
	* @param attributes is the attribute list of this element
	*/
	public void begin(String namespace, String name, Attributes attributes)
	throws Exception {
	oldRules = digester.getRules();
	newRules.init(digester.getMatch()+"/", oldRules);
	digester.setRules(newRules);
	}

	/**
	* This is only invoked after all child elements have been processed,
	* so we can remove the custom Rules object that does the
	* child-element-matching.
	*/
	public void body(String bodyText) throws Exception {
	digester.setRules(oldRules);
	}

	/**
	* <p>Add an additional element name to property name mapping.
	* This is intended to be used from the xml rules.
	*/
	public void addAlias(String elementName, String propertyName) {
	if (propertyName == null) {
	elementNames.put(elementName, PROP_IGNORE);
	}
	else {
	elementNames.put(elementName, propertyName);
	}
	}

	/**
	* Render a printable version of this Rule.
	*/
	public String toString() {

	return ("SetNestedPropertiesRule");
	}

	//----------------------------------------- local classes

	/** Private Rules implementation */
	private class AnyChildRules implements Rules {
	private String matchPrefix = null;
	private Rules decoratedRules = null;

	private ArrayList rules = new ArrayList(1);
	private AnyChildRule rule;

	public AnyChildRules(AnyChildRule rule) {
	this.rule = rule;
	rules.add(rule);
	}

	public Digester getDigester() { return null; }
	public void setDigester(Digester digester) {}
	public String getNamespaceURI() {return null;}
	public void setNamespaceURI(String namespaceURI) {}
	public void add(String pattern, Rule rule) {}
	public void clear() {}

	public List match(String matchPath) {
	return match(null,matchPath);
	}

	public List match(String namespaceURI, String matchPath) {
	List match = decoratedRules.match(namespaceURI, matchPath);

	if ((matchPath.startsWith(matchPrefix)) &&
	(matchPath.indexOf('/', matchPrefix.length()) == -1)) {

	// The current element is a direct child of the element
	// specified in the init method, so include it as the
	// first rule in the matches list. The way that
	// SetNestedPropertiesRule is used, it is in fact very
	// likely to be the only match, so we optimise that
	// solution by keeping a list with only the AnyChildRule
	// instance in it.

	if ((match == null \|\| match.size()==0)) {
	return rules;
	}
	else {
	// it might not be safe to modify the returned list,
	// so clone it first.
	LinkedList newMatch = new LinkedList(match);
	//newMatch.addFirst(rule);
	newMatch.addLast(rule);
	return newMatch;
	}
	}
	else {
	return match;
	}
	}

	public List rules() {
	// This is not actually expected to be called.
	throw new RuntimeException(
	"AnyChildRules.rules not implemented.");
	}

	public void init(String prefix, Rules rules) {
	matchPrefix = prefix;
	decoratedRules = rules;
	}
	}

	private class AnyChildRule extends Rule {
	private String currChildNamespaceURI = null;
	private String currChildElementName = null;

	public void begin(String namespaceURI, String name,
	Attributes attributes) throws Exception {

	currChildNamespaceURI = namespaceURI;
	currChildElementName = name;
	}

	public void body(String value) throws Exception {
	boolean debug = log.isDebugEnabled();

	String propName = (String) elementNames.get(currChildElementName);
	if (propName == PROP_IGNORE) {
	// note: above deliberately tests for IDENTITY, not EQUALITY
	return;
	}
	if (propName == null) {
	propName = currChildElementName;
	}

	if (digester.log.isDebugEnabled()) {
	digester.log.debug("[SetNestedPropertiesRule]{" + digester.match +
	"} Setting property '" + propName + "' to '" +
	value + "'");
	}

	// Populate the corresponding properties of the top object
	Object top = digester.peek();
	if (digester.log.isDebugEnabled()) {
	if (top != null) {
	digester.log.debug("[SetNestedPropertiesRule]{" + digester.match +
	"} Set " + top.getClass().getName() +
	" properties");
	} else {
	digester.log.debug("[SetPropertiesRule]{" + digester.match +
	"} Set NULL properties");
	}
	}

	if (trimData) {
	value = value.trim();
	}

	if (!allowUnknownChildElements) {
	// Force an exception if the property does not exist
	// (BeanUtils.setProperty() silently returns in this case)
	if (top instanceof DynaBean) {
	DynaProperty desc =
	((DynaBean) top).getDynaClass().getDynaProperty(propName);
	if (desc == null) {
	throw new NoSuchMethodException
	("Bean has no property named " + propName);
	}
	} else /* this is a standard JavaBean */ {
	PropertyDescriptor desc =
	PropertyUtils.getPropertyDescriptor(top, propName);
	if (desc == null) {
	throw new NoSuchMethodException
	("Bean has no property named " + propName);
	}
	}
	}

	BeanUtils.setProperty(top, propName, value);
	}

	public void end(String namespace, String name) throws Exception {
	currChildElementName = null;
	}
	}
	}