edu.upf.nets.mercury.mongo.DbObject.java Source code

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Here is the source code for edu.upf.nets.mercury.mongo.DbObject.java

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/* 
 * Copyright (C) 2013 Alex Bikfalvi
 *
 * 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 3 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.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 */

package edu.upf.nets.mercury.mongo;

import java.lang.reflect.Field;
import java.lang.reflect.Modifier;

import org.bson.types.ObjectId;

import com.mongodb.BasicDBObject;
import com.mongodb.DBObject;

/**
 * A class representing a database object to be stored in MongoDB.
 * @author Alex
 *
 */
public class DbObject {
    private ObjectId _id = null;

    /**
     * Creates a MongoDB object corresponding to the current object. 
     * @return
     * @throws IllegalAccessException 
     * @throws IllegalArgumentException 
     */
    public final BasicDBObject get() throws IllegalArgumentException, IllegalAccessException {
        // Create an empty database object.
        BasicDBObject object = new BasicDBObject();
        // Set the object ID field, if the current field.
        if (null != this._id) {
            object.append("_id", this._id);
        }
        // Get the class of the current object.
        Class<?> c = this.getClass();
        // Get all field for the class of the current object.
        Field[] fields = c.getDeclaredFields();
        // Add all field values using reflection.
        for (Field field : fields) {
            // Get the modifiers of the current field.
            int modifiers = field.getModifiers();
            // If the field is public, not static and not final.
            if (Modifier.isPublic(modifiers) && !Modifier.isStatic(modifiers) && !Modifier.isFinal(modifiers)) {
                // Get the field name.
                String name = field.getName();
                // Get the field value for the current object.
                Object value = field.get(this);
                // Add the field information to the database object.
                object = object.append(name, value);
            }
        }
        // Return the object.
        return object;
    }

    /**
     * Sets the fields of the current object from the specified database object.
     * @param object The database object.
     * @throws IllegalArgumentException
     * @throws IllegalAccessException
     */
    public final void set(DBObject object) throws IllegalArgumentException, IllegalAccessException {
        // Get the class of the current object.
        Class<?> c = this.getClass();
        // Get all field for the class of the current object.
        Field[] fields = c.getDeclaredFields();
        // Get the object ID.
        Object id = object.get("_id");
        if (null != id) {
            this._id = (ObjectId) id;
        }
        // Add the value to all fields using reflection.
        for (Field field : fields) {
            // If the field is accessible, not static and not final.
            if (field.isAccessible() && !Modifier.isStatic(field.getModifiers())
                    && !Modifier.isFinal(field.getModifiers())) {
                // Get the name of the current field.
                String name = field.getName();
                // Get the value of the database object.
                Object value = object.get(name);
                // Set the value to the field of the current object.
                field.set(this, value);
            }
        }
    }

    /**
     * Creates a new object from the given database object and of the specified type.
     * @param object The database object.
     * @param c The type class.
     * @return The new object.
     * @throws InstantiationException
     * @throws IllegalAccessException
     */
    public final static <T extends DbObject> T create(DBObject object, Class<T> c)
            throws InstantiationException, IllegalAccessException {
        // If the object is null, return null.
        if (null == object)
            return null;
        // Create a new instance of the target class.
        T value = c.newInstance();
        // Set all fields of the value object.
        value.set(object);
        // Return value.
        return value;
    }
}