FileSystemClassPathLocationScanner.java

/**
 * Copyright 2010-2015 Axel Fontaine
 * <p/>
 * 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
 * <p/>
 * http://www.apache.org/licenses/LICENSE-2.0
 * <p/>
 * 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 com.contrastsecurity.cassandra.migration.utils.scanner.classpath;

import com.contrastsecurity.cassandra.migration.logging.Log;
import com.contrastsecurity.cassandra.migration.logging.LogFactory;
import com.contrastsecurity.cassandra.migration.utils.UrlUtils;

import java.io.File;
import java.io.IOException;
import java.net.URL;
import java.util.Set;
import java.util.TreeSet;

/**
 * ClassPathLocationScanner for the file system.
 */
public class FileSystemClassPathLocationScanner implements ClassPathLocationScanner {
    private static final Log LOG = LogFactory.getLog(FileSystemClassPathLocationScanner.class);

    public Set<String> findResourceNames(String location, URL locationUrl) throws IOException {
        String filePath = UrlUtils.toFilePath(locationUrl);
        File folder = new File(filePath);
        if (!folder.isDirectory()) {
            LOG.debug("Skipping path as it is not a directory: " + filePath);
            return new TreeSet<String>();
        }

        String classPathRootOnDisk = filePath.substring(0, filePath.length() - location.length());
        if (!classPathRootOnDisk.endsWith(File.separator)) {
            classPathRootOnDisk = classPathRootOnDisk + File.separator;
        }
        LOG.debug("Scanning starting at classpath root in filesystem: " + classPathRootOnDisk);
        return findResourceNamesFromFileSystem(classPathRootOnDisk, location, folder);
    }

    /**
     * Finds all the resource names contained in this file system folder.
     *
     * @param classPathRootOnDisk The location of the classpath root on disk, with a trailing slash.
     * @param scanRootLocation    The root location of the scan on the classpath, without leading or trailing slashes.
     * @param folder              The folder to look for resources under on disk.
     * @return The resource names;
     * @throws IOException when the folder could not be read.
     */
    /*private -> for testing*/
    @SuppressWarnings("ConstantConditions")
    Set<String> findResourceNamesFromFileSystem(String classPathRootOnDisk, String scanRootLocation, File folder) throws IOException {
        LOG.debug("Scanning for resources in path: " + folder.getPath() + " (" + scanRootLocation + ")");

        Set<String> resourceNames = new TreeSet<String>();

        File[] files = folder.listFiles();
        for (File file : files) {
            if (file.canRead()) {
                if (file.isDirectory()) {
                    resourceNames.addAll(findResourceNamesFromFileSystem(classPathRootOnDisk, scanRootLocation, file));
                } else {
                    resourceNames.add(toResourceNameOnClasspath(classPathRootOnDisk, file));
                }
            }
        }

        return resourceNames;
    }

    /**
     * Converts this file into a resource name on the classpath.
     *
     * @param classPathRootOnDisk The location of the classpath root on disk, with a trailing slash.
     * @param file                The file.
     * @return The resource name on the classpath.
     * @throws IOException when the file could not be read.
     */
    private String toResourceNameOnClasspath(String classPathRootOnDisk, File file) throws IOException {
        String fileName = file.getAbsolutePath().replace("\\", "/");

        //Cut off the part on disk leading to the root of the classpath
        //This leaves a resource name starting with the scanRootLocation,
        //   with no leading slash, containing subDirs and the fileName.
        return fileName.substring(classPathRootOnDisk.length());
    }
}