org.openbp.common.property.PropertyAccessUtil.java Source code

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Here is the source code for org.openbp.common.property.PropertyAccessUtil.java

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/*
 *   Copyright 2007 skynamics AG
 *
 *   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.openbp.common.property;

import java.lang.reflect.InvocationTargetException;

import org.apache.commons.beanutils.NestedNullException;
import org.apache.commons.beanutils.PropertyUtils;
import org.openbp.common.string.StringUtil;

/**
 * Utility class that provides methods to access properties of an object dynamically.
 * Wraps Apache Common-PropertyUtils.
 *
 * @author Heiko Erhardt
 */
public final class PropertyAccessUtil {
    /**
     * Private constructor prevents instantiation.
     */
    private PropertyAccessUtil() {
    }

    /**
     * Gets the value of the specified property of an object.
     * This just wraps the Apache Common-PropertyUtils class in convenient exception handling.
     *
     * @param base Object that holds the property
     * @param property Property name; all property access methods supported by PropertyUtils is valid.
     * @return The value of the property
     * @throws PropertyException If no appropriate access method could be found or if the invocation
     * of one of the property access methods failed. The nested exception describes the error in detail.
     */
    public static Object getProperty(Object base, String property) throws PropertyException {
        // TODO Doesn't work for property chains; actually, decapitalization should be removed and the descriptors should be corrected.
        property = StringUtil.decapitalize(property);

        if (base == null)
            throw new PropertyException("Cannot access property '" + property + "' with null base object.");

        Object ret = null;
        Exception ex = null;
        try {
            ret = PropertyUtils.getProperty(base, property);
        } catch (NestedNullException e) {
            // Ignore nested nulls
        } catch (IllegalAccessException e) {
            ex = e;
        } catch (IllegalArgumentException e) {
            ex = e;
        } catch (InvocationTargetException e) {
            ex = e;
        } catch (NoSuchMethodException e) {
            ex = e;
        }
        if (ex != null) {
            throw new PropertyException("Error accessing property '" + property + "' of object of type '"
                    + base.getClass().getName() + "'.", ex);
        }
        return ret;
    }

    /**
     * Sets the value of the specified property of an object.
     * In order to access the property, the method uses the following strategy.
     * We assume the name of the property is "Sample"
     * <ol>
     * <li>Search for a method named get\iSample\i</li>
     * <li>Try direct field access on the member \isample\i</li>
     * <li>Try to use map-style access to properties by calling the method get("Sample")</li>
     * </ol>
     *
     * @param base Object to invoke the method on
     * @param property Property name<br>
     * @param value Property value
     * Property chains of the form "prop1.prop2" are *not* supported.
     * @throws PropertyException If no appropriate access method could be found or if the invocation
     * of one of the property access methods failed.<br>
     * The nested exception describes the error in detail.
     */
    public static void setProperty(Object base, String property, Object value) throws PropertyException {
        // TODO Doesn't work for property chains; actually, decapitalization should be removed and the descriptors should be corrected.
        property = StringUtil.decapitalize(property);

        if (base == null)
            throw new PropertyException("Cannot access property '" + property + "' with null base object.");

        Exception ex = null;
        try {
            PropertyUtils.setProperty(base, property, value);
        } catch (NestedNullException e) {
            ex = e;
        } catch (IllegalAccessException e) {
            ex = e;
        } catch (IllegalArgumentException e) {
            ex = e;
        } catch (InvocationTargetException e) {
            ex = e;
        } catch (NoSuchMethodException e) {
            ex = e;
        }
        if (ex != null) {
            String valueType = value != null ? value.getClass().getName() : null;
            throw new PropertyException("Error setting property '" + property + "' of object of type '"
                    + base.getClass().getName() + "' to value of type '" + valueType + "'.", ex);
        }
    }
}