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'databene commons' is an open source Java library by Volker Bergmann. It provides extensions to the Java core library by utility classes, abstract concepts and concrete implementations.
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/*
 * Copyright (C) 2004-2015 Volker Bergmann ([email protected]).
 * All rights reserved.
 *
 * 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.databene.commons.bean;

import org.databene.commons.BeanUtil;
import org.databene.commons.ConfigurationError;

import java.beans.PropertyDescriptor;

/**
 * Creates PropertyAccessors that are as efficient as possible depending on the information provided.
 * The fastest accessors are available when the bean class is provided with the property name.
 * property names may express navigation over refering JavaBean entities, e.g. 'category.name'.
 * A PropertyAccessor in a non-strict mode converts the invocation argument to the correct property type
 * and behaves quietly, if it doesn not find the specified property
 * Created: 06.01.2005 20:04:36
 * @author Volker Bergmann
 */
@SuppressWarnings("unchecked")
public class PropertyAccessorFactory {

    /** private constructor for preventing that the class is instantiated */
    private PropertyAccessorFactory() {
    }

    /**
     * @param propertyName the name of the property to access
     * @return a property accessor without knowledge about the bean type
     * (the slowest PropertyAccessor type) in strict mode.
     */
    @SuppressWarnings("rawtypes")
	public static PropertyAccessor getAccessor(String propertyName) {
        return getAccessor(null, propertyName);
    }

    /**
     * @param propertyName the name of the property to access
     * @param strict set to true if the property must exist
     * @return a property accessor of the specified strictness.
     */
    @SuppressWarnings("rawtypes")
	public static PropertyAccessor getAccessor(String propertyName, boolean strict) {
        return getAccessor(null, propertyName, strict);
    }

    /**
     * @return a property accessor without knowledge about the bean type
     * (the slowest PropertyAccessor type) in strict mode.
     */
/*
    public static PropertyAccessor getAccessor(String propertyName, Class propertyType) {
        return getAccessor(null, propertyName, propertyType, true);
    }
*/
    /**
     * @param beanClass the bean type to access
     * @param propertyName the name of the property to access
     * @return a property accessor in strict mode.
     */
    @SuppressWarnings("rawtypes")
	public static PropertyAccessor getAccessor(Class beanClass, String propertyName) {
        return getAccessor(beanClass, propertyName, true);
    }

    /**
     * @param beanClass the bean type to access 
     * @param propertyName the name of the property to access
     * @param strict set to true if the property must exist
     * @return a property accessor of the specified strictness.
     */
    @SuppressWarnings("rawtypes")
	public static PropertyAccessor getAccessor(Class beanClass, String propertyName, boolean strict) {
        if (beanClass != null) {
            PropertyDescriptor propertyDescriptor = BeanUtil.getPropertyDescriptor(beanClass, propertyName);
            if (propertyDescriptor == null) {
                if (strict)
                    throw new ConfigurationError("No property '" + propertyName + "' found in " + beanClass);
            }
        }
        int index = propertyName.indexOf('.');
        if (index < 0) {
            if (beanClass == null)
                return new UntypedPropertyAccessor(propertyName, strict);
            else
                return new TypedPropertyAccessor(beanClass, propertyName, strict);
        } else
            return new PropertyGraphAccessor(beanClass, propertyName, strict);
    }

}