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Commons Digester example source code file (SetPropertyRule.java)

This example Commons Digester source code file (SetPropertyRule.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - Commons Digester tags/keywords

bean, bean, deprecated, dynabean, dynaproperty, javabean, javabean, nosuchmethodexception, nosuchmethodexception, override, sax, setpropertyrule, setpropertyrule, string, string, stringbuffer

The Commons Digester SetPropertyRule.java source code

/* $Id: SetPropertyRule.java 992060 2010-09-02 19:09:47Z simonetripodi $
 *
 * 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;


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;


/**
 * Rule implementation that sets an individual property on the object at the
 * top of the stack, based on attributes with specified names.
 */

public class SetPropertyRule extends Rule {


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


    /**
     * Construct a "set property" rule with the specified name and value
     * attributes.
     *
     * @param digester The digester with which this rule is associated
     * @param name Name of the attribute that will contain the name of the
     *  property to be set
     * @param value Name of the attribute that will contain the value to which
     *  the property should be set
     *
     * @deprecated The digester instance is now set in the {@link Digester#addRule} method. 
     * Use {@link #SetPropertyRule(String name, String value)} instead.
     */
    @Deprecated
    public SetPropertyRule(Digester digester, String name, String value) {

        this(name, value);

    }

    /**
     * Construct a "set property" rule with the specified name and value
     * attributes.
     *
     * @param name Name of the attribute that will contain the name of the
     *  property to be set
     * @param value Name of the attribute that will contain the value to which
     *  the property should be set
     */
    public SetPropertyRule(String name, String value) {

        this.name = name;
        this.value = value;

    }

    // ----------------------------------------------------- Instance Variables


    /**
     * The attribute that will contain the property name.
     */
    protected String name = null;


    /**
     * The attribute that will contain the property value.
     */
    protected String value = null;


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


    /**
     * Process the beginning of this element.
     *
     * @param attributes The attribute list of this element
     *
     * @exception NoSuchMethodException if the bean does not
     *  have a writeable property of the specified name
     */
    @Override
    public void begin(Attributes attributes) throws Exception {

        if (attributes.getLength() == 0 ) {
            return;
        }

        // Identify the actual property name and value to be used
        String actualName = null;
        String actualValue = null;
        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);
            if (name.equals(this.name)) {
                actualName = value;
            } else if (name.equals(this.value)) {
                actualValue = value;
            }
        }

        // Get a reference to the top object
        Object top = digester.peek();

        // Log some debugging information
        if (digester.log.isDebugEnabled()) {
            digester.log.debug("[SetPropertyRule]{" + digester.match +
                    "} Set " + top.getClass().getName() + " property " +
                    actualName + " to " + actualValue);
        }

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

        // Set the property (with conversion as necessary)
        BeanUtils.setProperty(top, actualName, actualValue);

    }


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

        StringBuffer sb = new StringBuffer("SetPropertyRule[");
        sb.append("name=");
        sb.append(name);
        sb.append(", value=");
        sb.append(value);
        sb.append("]");
        return (sb.toString());

    }


}

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