no.abmu.util.reflection.FieldUtil.java Source code

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Here is the source code for no.abmu.util.reflection.FieldUtil.java

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/*$Id: FieldUtil.java 9779 2008-05-11 15:32:40Z jens $*/
/*
 ****************************************************************************
 *                                                                          *
 *                   (c) Copyright 2008 ABM-utvikling                       *
 *                                                                          *
 * This program is free software; you can redistribute it and/or modify it  *
 * under the terms of the GNU General Public License as published by the    *
 * Free Software Foundation; either version 2 of the License, or (at your   *
 * option) any later version.                                               *
 *                                                                          *
 * This program is distributed in the hope that it will be useful, but      *
 * WITHOUT ANY WARRANTY; without even the implied warranty of               *
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General *
 * Public License for more details. http://www.gnu.org/licenses/gpl.html    *
 *                                                                          *
 ****************************************************************************
 */

package no.abmu.util.reflection;

import java.lang.reflect.Field;
import java.lang.reflect.Modifier;
import java.util.LinkedHashSet;
import java.util.Set;

import no.abmu.util.test.Assert;

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

/**
 * This class provides a set of static methods that
 * extend the Java meta object protocol, with focus on 
 * fields/variables.
 * 
 * @author Jens Vindvad, Jens.Vindvad@abm-utvikling.no
 * @author $Author:jens $
 * @version $Rev: 9779 $
 * $Date: 2008-05-11 17:32:40 +0200 (Sun, 11 May 2008) $
 * copyright ABM-Utvikling
 * since 2008-05-10
 */
public final class FieldUtil {

    private static final Log logger = (Log) LogFactory.getLog(FieldUtil.class);

    // Suppress default constructor for noninstantiability.
    private FieldUtil() {
        // This constructor will never be invoked.
        // See Item 3 on page 12 in
        // Joshua Bloch: Effective Java: Programming Language Guide, 2001
        // ISBN 0-201-31005-8
    }

    /**
     * Returns all fields/variables of object, also all
     * the inheritages. 
     * 
     * @param obj
     * @return
     */
    public static Set<Field> getAllValiables(Object obj) {
        Assert.checkRequiredArgument("obj", obj);

        Class cls = obj.getClass();
        Set<Field> fields = new LinkedHashSet<Field>();

        while (cls != null) {
            Field[] f = cls.getDeclaredFields();
            for (int i = 0; i < f.length; i++) {
                fields.add(f[i]);
            }
            cls = cls.getSuperclass();
        }

        return fields;
    }

    public static boolean hasObjectVariable(Object obj, String fieldName) {
        Assert.checkRequiredArgument("obj", obj);
        Assert.checkRequiredArgument("fieldName", fieldName);

        return (getField(obj, fieldName) != null);
    }

    public static Field getField(Object obj, String fieldName) {
        Assert.checkRequiredArgument("obj", obj);
        Assert.checkRequiredArgument("fieldName", fieldName);

        Field field = null;
        Set<Field> fieldsInObject = getAllValiables(obj);

        for (Field fieldInObject : fieldsInObject) {
            if (fieldName.equals(fieldInObject.getName())) {
                field = fieldInObject;
                break;
            }
        }

        return field;
    }

    public static boolean setFieldValueToNull(Object obj, String fieldName) {
        Assert.checkRequiredArgument("obj", obj);
        Assert.checkRequiredArgument("fieldName", fieldName);
        String errorMessage = "Object '" + obj.getClass().getName() + " does not have field/variable with name '"
                + fieldName + "'";
        Assert.assertTrue(errorMessage, hasObjectVariable(obj, fieldName));

        Field field = getField(obj, fieldName);
        String fieldType = field.getType().toString();

        // This list has to be extended when nessesary
        // System.out.println("FieldName '" + fieldName + "' has type='" + fieldType + "'");
        if (fieldType.equals("int")) {
            return setFieldValue(obj, fieldName, 0);
        } else if (fieldType.equals("long")) {
            return setFieldValue(obj, fieldName, 0);
        } else if (fieldType.equals("boolean")) {
            return setFieldValue(obj, fieldName, false);
        }

        return setFieldValue(obj, fieldName, null);
    }

    public static Object getFieldValue(Object obj, String fieldName) {
        Assert.checkRequiredArgument("obj", obj);
        Assert.checkRequiredArgument("fieldName", fieldName);
        String errorMessage = "Object '" + obj.getClass().getName() + " does not have field/variable with name '"
                + fieldName + "'";
        Assert.assertTrue(errorMessage, hasObjectVariable(obj, fieldName));

        Field field = getField(obj, fieldName);

        Object value = null;
        try {
            if (Modifier.isPublic(field.getModifiers())) {
                value = field.get(obj);
            } else {
                field.setAccessible(true);
                value = field.get(obj);
                field.setAccessible(false);
            }
        } catch (IllegalAccessException e) {
            logger.error(e.getMessage());
        }

        return value;
    }

    public static boolean setFieldValue(Object obj, String fieldName, Object value) {
        Assert.checkRequiredArgument("obj", obj);
        Assert.checkRequiredArgument("fieldName", fieldName);
        String errorMessage = "Object '" + obj.getClass().getName() + " does not have field/variable with name '"
                + fieldName + "'";
        Assert.assertTrue(errorMessage, hasObjectVariable(obj, fieldName));

        Field field = getField(obj, fieldName);

        boolean sucess = false;
        try {
            if (Modifier.isPublic(field.getModifiers())) {
                field.set(obj, value);
            } else {
                field.setAccessible(true);
                field.set(obj, value);
                field.setAccessible(false);
            }
            sucess = true;
        } catch (IllegalAccessException e) {
            logger.warn(e.getMessage());
        }

        return sucess;
    }

}