com.sun.grizzly.smart.Reference Maven / Gradle / Ivy

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/*
 *
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
 *
 * Copyright 2007-2008 Sun Microsystems, Inc. All rights reserved.
 *
 * The contents of this file are subject to the terms of either the GNU
 * General Public License Version 2 only ("GPL") or the Common Development
 * and Distribution License("CDDL") (collectively, the "License").  You
 * may not use this file except in compliance with the License. You can obtain
 * a copy of the License at https://glassfish.dev.java.net/public/CDDL+GPL.html
 * or glassfish/bootstrap/legal/LICENSE.txt.  See the License for the specific
 * language governing permissions and limitations under the License.
 *
 * When distributing the software, include this License Header Notice in each
 * file and include the License file at glassfish/bootstrap/legal/LICENSE.txt.
 * Sun designates this particular file as subject to the "Classpath" exception
 * as provided by Sun in the GPL Version 2 section of the License file that
 * accompanied this code.  If applicable, add the following below the License
 * Header, with the fields enclosed by brackets [] replaced by your own
 * identifying information: "Portions Copyrighted [year]
 * [name of copyright owner]"
 *
 * Contributor(s):
 *
 * If you wish your version of this file to be governed by only the CDDL or
 * only the GPL Version 2, indicate your decision by adding "[Contributor]
 * elects to include this software in this distribution under the [CDDL or GPL
 * Version 2] license."  If you don't indicate a single choice of license, a
 * recipient has the option to distribute your version of this file under
 * either the CDDL, the GPL Version 2 or to extend the choice of license to
 * its licensees as provided above.  However, if you add GPL Version 2 code
 * and therefore, elected the GPL Version 2 license, then the option applies
 * only if the new code is made subject to such option by the copyright
 * holder.
 *
 */

package com.sun.grizzly.smart;

import java.lang.reflect.AccessibleObject;
import java.lang.reflect.Field;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.LinkedList;
import java.util.List;

/**
 * Object represents reference to a value
 * 
 * @author Alexey Stashok
 */
public class Reference {
    private List path = new LinkedList();

    public Reference(Class root, String ref) {
        try {
            buildPath(root, ref, path);
        } catch (Exception e) {
            throw new IllegalStateException(e);
        }
    }

    public E get(Object rootInstance) throws IllegalArgumentException,
            IllegalAccessException,
            InvocationTargetException {
        Object currentValue = rootInstance;
        
        for(AccessibleObject accessor : path) {
            if (accessor instanceof Field) {
                currentValue = ((Field) accessor).get(currentValue);
            } else {
                currentValue = ((Method) accessor).invoke(rootInstance);
            }
        }

        return (E) currentValue;
    }

    protected static void buildPath(Class root, String ref, List path)
            throws Exception {
        Class currentClass = root;

        String[] steps = ref.split("/");
        for(String step : steps) {
            step = step.trim();
            if (step.length() == 0) continue;

            try {
                Field field = currentClass.getDeclaredField(step);
                field.setAccessible(true);
                path.add(field);
                currentClass = field.getType();
            } catch (NoSuchFieldException fe) {
                Method method = currentClass.getDeclaredMethod(
                        makeGetter(step));
                path.add(method);
                method.setAccessible(true);
                currentClass = method.getReturnType();
            }
        }
    }

    private static String makeGetter(String field) {
        StringBuilder builder = new StringBuilder("get");
        builder.append(Character.toUpperCase(field.charAt(0)));

        if (field.length() > 1) {
            builder.append(field, 1, field.length());
        }
        
        return builder.toString();
    }
}