org.o3project.odenos.core.util.ComponentLoader.java Source code

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Here is the source code for org.o3project.odenos.core.util.ComponentLoader.java

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/*
 * Copyright 2015 NEC 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 org.o3project.odenos.core.util;

import org.apache.commons.io.FilenameUtils;
import org.o3project.odenos.remoteobject.RemoteObject;

import java.io.File;
import java.io.IOException;
import java.net.URL;
import java.net.URLClassLoader;
import java.util.ArrayList;
import java.util.List;

public final class ComponentLoader {
    private static ClassLoader classLoader;

    /**
     * create Class Loader.
     * @param dirname package path name.
     * @return class loader.
     * @throws IOException exception.
     */
    public static ClassLoader createClassLoader(final String dirname) throws IOException {
        URL[] url = new URL[1];
        File file;
        if (dirname.endsWith("/")) {
            file = new File(dirname);
        } else {
            file = new File(dirname + "/");
        }
        url[0] = file.toURI().toURL();

        ClassLoader parent = ClassLoader.getSystemClassLoader();
        URLClassLoader loader = new URLClassLoader(url, parent);

        return loader;
    }

    /**
     * Load packages.
     * @param rootOfPackages class package path name.
     * @return list of remote object.
     * @throws Exception failed to create class loader.
     */
    public static List<Class<? extends RemoteObject>> load(final String rootOfPackages) throws Exception {
        classLoader = createClassLoader(rootOfPackages);

        File rootDir = new File(System.getProperty("user.dir") + "/" + rootOfPackages);
        List<Class<? extends RemoteObject>> result = new ArrayList<Class<? extends RemoteObject>>();
        find("", rootDir, result);

        return result;
    }

    @SuppressWarnings("unchecked")
    private static void find(final String parentPackage, final File dir, List<Class<? extends RemoteObject>> result)
            throws Exception {
        String packageName = parentPackage;
        if (!packageName.equals("")) {
            packageName += ".";
        }

        File[] entries = dir.listFiles();
        if (entries == null) {
            return;
        }

        for (File entry : entries) {
            if (entry.isDirectory()) {
                find(packageName + entry.getName(), entry, result);
            } else {
                if (!isClassFile(entry)) {
                    continue;
                }
                String filename = entry.getName();
                String className = packageName + FilenameUtils.removeExtension(filename);
                Class<?> clazz = classLoader.loadClass(className);
                if (RemoteObject.class.isAssignableFrom(clazz)) {
                    System.out.println("Loading... " + className);
                    result.add((Class<? extends RemoteObject>) clazz);
                }
            }
        }
    }

    private static boolean isClassFile(final File file) {
        String filename = file.getName();
        return FilenameUtils.isExtension(filename, "class");
    }
}