JXPathBasicBeanInfo.java

/*
 * 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.jxpath;

import java.beans.BeanInfo;
import java.beans.IntrospectionException;
import java.beans.Introspector;
import java.beans.PropertyDescriptor;
import java.util.Arrays;
import java.util.Comparator;
import java.util.HashMap;

/**
 * An implementation of JXPathBeanInfo based on JavaBeans' BeanInfo. Properties
 * advertised by JXPathBasicBeanInfo are the same as those advertised by
 * BeanInfo for the corresponding class.
 *
 * @see java.beans.BeanInfo
 * @see java.beans.Introspector
 *
 * @author Dmitri Plotnikov
 * @version $Revision: 668329 $ $Date: 2008-06-16 16:59:48 -0500 (Mon, 16 Jun 2008) $
 */
public class JXPathBasicBeanInfo implements JXPathBeanInfo {
    private static final long serialVersionUID = -3863803443111484155L;

    private static final Comparator PROPERTY_DESCRIPTOR_COMPARATOR = new Comparator() {
        public int compare(Object left, Object right) {
            return ((PropertyDescriptor) left).getName().compareTo(
                ((PropertyDescriptor) right).getName());
        }
    };

    private boolean atomic = false;
    private Class clazz;
    private Class dynamicPropertyHandlerClass;
    private transient PropertyDescriptor[] propertyDescriptors;
    private transient HashMap propertyDescriptorMap;

    /**
     * Create a new JXPathBasicBeanInfo.
     * @param clazz bean class
     */
    public JXPathBasicBeanInfo(Class clazz) {
        this.clazz = clazz;
    }

    /**
     * Create a new JXPathBasicBeanInfo.
     * @param clazz bean class
     * @param atomic whether objects of this class are treated as atomic
     *               objects which have no properties of their own.
     */
    public JXPathBasicBeanInfo(Class clazz, boolean atomic) {
        this.clazz = clazz;
        this.atomic = atomic;
    }

    /**
     * Create a new JXPathBasicBeanInfo.
     * @param clazz bean class
     * @param dynamicPropertyHandlerClass dynamic property handler class
     */
    public JXPathBasicBeanInfo(Class clazz, Class dynamicPropertyHandlerClass) {
        this.clazz = clazz;
        this.atomic = false;
        this.dynamicPropertyHandlerClass = dynamicPropertyHandlerClass;
    }

    /**
     * Returns true if objects of this class are treated as atomic
     * objects which have no properties of their own.
     * @return boolean
     */
    public boolean isAtomic() {
        return atomic;
    }

    /**
     * Return true if the corresponding objects have dynamic properties.
     * @return boolean
     */
    public boolean isDynamic() {
        return dynamicPropertyHandlerClass != null;
    }

    public synchronized PropertyDescriptor[] getPropertyDescriptors() {
        if (propertyDescriptors == null) {
            if (clazz == Object.class) {
                propertyDescriptors = new PropertyDescriptor[0];
            }
            else {
                try {
                    BeanInfo bi = null;
                    if (clazz.isInterface()) {
                        bi = Introspector.getBeanInfo(clazz);
                    }
                    else {
                        bi = Introspector.getBeanInfo(clazz, Object.class);
                    }
                    PropertyDescriptor[] pds = bi.getPropertyDescriptors();
                    PropertyDescriptor[] descriptors = new PropertyDescriptor[pds.length];
                    System.arraycopy(pds, 0, descriptors, 0, pds.length);
                    Arrays.sort(descriptors, PROPERTY_DESCRIPTOR_COMPARATOR);
                    propertyDescriptors = descriptors;
                }
                catch (IntrospectionException ex) {
                    ex.printStackTrace();
                }
            }
        }
        if (propertyDescriptors.length == 0) {
            return propertyDescriptors;
        }
        PropertyDescriptor[] result = new PropertyDescriptor[propertyDescriptors.length];
        System.arraycopy(propertyDescriptors, 0, result, 0, propertyDescriptors.length);
        return result;
    }

    public synchronized PropertyDescriptor getPropertyDescriptor(String propertyName) {
        if (propertyDescriptorMap == null) {
            propertyDescriptorMap = new HashMap();
            PropertyDescriptor[] pds = getPropertyDescriptors();
            for (int i = 0; i < pds.length; i++) {
                propertyDescriptorMap.put(pds[i].getName(), pds[i]);
            }
        }
        return (PropertyDescriptor) propertyDescriptorMap.get(propertyName);
    }

    /**
     * For a dynamic class, returns the corresponding DynamicPropertyHandler
     * class.
     * @return Class
     */
    public Class getDynamicPropertyHandlerClass() {
        return dynamicPropertyHandlerClass;
    }

    public String toString() {
        StringBuffer buffer = new StringBuffer();
        buffer.append("BeanInfo [class = ");
        buffer.append(clazz.getName());
        if (isDynamic()) {
            buffer.append(", dynamic");
        }
        if (isAtomic()) {
            buffer.append(", atomic");
        }
        buffer.append(", properties = ");
        PropertyDescriptor[] jpds = getPropertyDescriptors();
        for (int i = 0; i < jpds.length; i++) {
            buffer.append("\n    ");
            buffer.append(jpds[i].getPropertyType());
            buffer.append(": ");
            buffer.append(jpds[i].getName());
        }
        buffer.append("]");
        return buffer.toString();
    }
}