jp.co.ctc_g.jfw.core.util.Classes.java Source code

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Here is the source code for jp.co.ctc_g.jfw.core.util.Classes.java

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/*
 * Copyright (c) 2013 ITOCHU Techno-Solutions Corporation.
 *
 * 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 jp.co.ctc_g.jfw.core.util;

import java.util.ResourceBundle;

import jp.co.ctc_g.jfw.core.internal.InternalMessages;

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

/**
 * <p>
 * ??????????????
 * </p>
 * @author ITOCHU Techno-Solutions Corporation.
 */
public final class Classes {

    private static final Log L = LogFactory.getLog(Classes.class);

    private static final ResourceBundle R = InternalMessages.getBundle(Classes.class);

    private Classes() {
    }

    /**
     * ?????
     * ???????????
     * ???????????????
     * @return ?
     */
    public static ClassLoader preferredClassLoader() {
        ClassLoader loader = null;
        try {
            loader = Thread.currentThread().getContextClassLoader();
        } catch (SecurityException e) {
            // ???????????????
            // ??????(???????)
        }
        if (loader == null) {
            loader = Classes.class.getClassLoader();
        }
        return loader;
    }

    /**
     * ????????
     * ???{@link #preferredClassLoader()}??????
     * @param <T> ??
     * @param className ????
     * @return 
     */
    @SuppressWarnings("unchecked")
    public static <T> Class<T> forName(String className) {
        return (Class<T>) forName(className, preferredClassLoader());
    }

    /**
     * ????????
     * @param <T> ??
     * @param className ????
     * @param loader ?
     * @return 
     */
    @SuppressWarnings("unchecked")
    public static <T> Class<T> forName(String className, ClassLoader loader) {
        Args.checkNotBlank(className);
        loader = loader == null ? preferredClassLoader() : loader;
        Class<?> clazz = null;
        try {
            clazz = Class.forName(className, true, loader);
        } catch (ClassNotFoundException e) {
            if (L.isDebugEnabled()) {
                String message = Strings.substitute(R.getString("D-UTIL#0001"), Maps.hash("class", className));
                L.debug(message);
            }
        }
        return (Class<T>) clazz;
    }

    /**
     * ???????????????
     * ?????????
     * ??????
     * <pre class="brush:java">
     * Classes.howFar(Object.class, Object.class); // 0
     * Classes.howFar(String.class, Object.class); // 1
     * Classes.howFar(JPanel.class, Object.class); // 4
     * Classes.howFar(JPanel.class, JComponent.class); // 1
     * </pre>
     * ?????????<code>-1</code>?????
     * @param from ??
     * @param to ??
     * @return ??
     */
    public static int howFar(Class<?> from, Class<?> to) {
        Args.checkNotNull(from);
        Args.checkNotNull(to);
        if (from == to)
            return 0;
        if (!to.isAssignableFrom(from))
            return -1;
        int distance = 0;
        Class<?> hierarchyExplorer = from;
        while (hierarchyExplorer != null && hierarchyExplorer != to) {
            hierarchyExplorer = hierarchyExplorer.getSuperclass();
            if (hierarchyExplorer != null) {
                distance++;
            } else {
                // ???????????????
                assert false;
            }
        }
        return distance;
    }

}