org.wicketstuff.rest.utils.mounting.PackageScanner.java Source code

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Here is the source code for org.wicketstuff.rest.utils.mounting.PackageScanner.java

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/**
 *  Licensed to the Apache Software Foundation (ASF) under one or more
 *  contributor license agreements.  See the NOTICE file distributed with
 *  this work for additional information regarding copyright ownership.
 *  The ASF licenses this file to You 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.wicketstuff.rest.utils.mounting;

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

import org.apache.wicket.WicketRuntimeException;
import org.apache.wicket.protocol.http.WebApplication;
import org.apache.wicket.request.resource.IResource;
import org.apache.wicket.request.resource.ResourceReference;
import org.apache.wicket.util.lang.Args;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.wicketstuff.rest.annotations.ResourcePath;

public class PackageScanner {
    private static final Logger log = LoggerFactory.getLogger(PackageScanner.class);

    public static void scanPackage(String... packageNames) {
        Args.notNull(packageNames, "packageNames");

        scanPackage(WebApplication.get(), packageNames);
    }

    public static void scanPackage(WebApplication application, String... packageNames) {
        Args.notNull(application, "application");
        Args.notNull(packageNames, "packageNames");

        for (String packageName : packageNames) {
            scanPackage(application, packageName);
        }
    }

    public static void scanPackage(WebApplication application, String packageName) {
        Args.notNull(application, "application");
        Args.notNull(packageName, "packageName");

        try {
            Class<?>[] packageClasses = getClasses(packageName);

            for (Class<?> clazz : packageClasses) {
                mountAnnotatedResource(application, clazz);
            }

        } catch (Exception exception) {
            throw new WicketRuntimeException(exception);
        }
    }

    private static void mountAnnotatedResource(WebApplication application, Class<?> clazz)
            throws InstantiationException, IllegalAccessException {
        ResourcePath mountAnnotation = clazz.getAnnotation(ResourcePath.class);

        if (mountAnnotation == null || !IResource.class.isAssignableFrom(clazz)) {
            return;
        }

        String path = mountAnnotation.value();
        final IResource resourceInstance = (IResource) clazz.newInstance();

        application.mountResource(path, new ResourceReference(clazz.getSimpleName()) {
            /**
                 * 
              */
            private static final long serialVersionUID = 1L;

            @Override
            public IResource getResource() {
                return resourceInstance;
            }
        });

        log.info("Resource '" + clazz.getSimpleName() + "' has been mounted to path '" + path + "'");
    }

    /**
     * Scans all classes accessible from the context class loader which belong
     * to the given package and subpackages.
     * 
     * Credits: http://www.dzone.com/snippets/get-all-classes-within-package
     * 
     * @param packageName
     *            The base package
     * @return The classes
     * @throws ClassNotFoundException
     * @throws IOException
     */
    private static Class<?>[] getClasses(String packageName) throws ClassNotFoundException, IOException {
        ClassLoader classLoader = Thread.currentThread().getContextClassLoader();

        Args.notNull(classLoader, "classLoader");

        String path = packageName.replace('.', '/');
        Enumeration<URL> resources = classLoader.getResources(path);
        List<File> dirs = new ArrayList<File>();

        while (resources.hasMoreElements()) {
            URL resource = resources.nextElement();
            dirs.add(new File(resource.getFile()));
        }

        ArrayList<Class<?>> classes = new ArrayList<Class<?>>();

        for (File directory : dirs) {
            classes.addAll(findClasses(directory, packageName));
        }

        return classes.toArray(new Class[classes.size()]);
    }

    /**
     * Recursive method used to find all classes in a given directory and
     * subdirs.
     * 
     * Credits: http://www.dzone.com/snippets/get-all-classes-within-package
     * 
     * @param directory
     *            The base directory
     * @param packageName
     *            The package name for classes found inside the base directory
     * @return The classes
     * @throws ClassNotFoundException
     */
    private static List<Class<?>> findClasses(File directory, String packageName) throws ClassNotFoundException {
        List<Class<?>> classes = new ArrayList<Class<?>>();

        if (!directory.exists()) {
            return classes;
        }

        File[] files = directory.listFiles();

        for (File file : files) {
            if (file.isDirectory()) {
                classes.addAll(findClasses(file, packageName + "." + file.getName()));
            } else if (file.getName().endsWith(".class")) {
                classes.add(Class
                        .forName(packageName + '.' + file.getName().substring(0, file.getName().length() - 6)));
            }
        }

        return classes;
    }

}