Unit Test Support File Resolver

import java.io.File;
import java.io.UnsupportedEncodingException;
import java.net.URL;
import java.net.URLClassLoader;
import java.net.URLDecoder;

import org.apache.log4j.Logger;

import com.eztech.file.FileUtils;
import com.eztech.util.StringUtil;

/**
 * Class to make support files in unit tests more portable by allowing them to
 * live in different directories for different environment. Uses
 * ClassLoader.getSystemResource to resolve the name of the file to its path.
 *
 * @author Sam
 *
 */
public class SupportFilePathResolver {

    public static final String DEFAULT_SUPPORT_FILE_FOLDER = "supportfiles";

    /**
     * Setting this to true, will cause this to print the Classpath to STDERR if
     * it fails to look up a file
     */
    public static boolean dumpClasspathOnError = false;

    private static final Logger LOG = Logger.getLogger(SupportFilePathResolver.class);

    private static SupportFilePathResolver instance;
    private String baseSupportFileFolder = DEFAULT_SUPPORT_FILE_FOLDER;

    public String getBaseSupportFileFolder() {
        return baseSupportFileFolder;
    }

    public void setBaseSupportFileFolder(String baseSupportFileFolder) {
        this.baseSupportFileFolder = baseSupportFileFolder;
    }

    public SupportFilePathResolver() {
    }

    public SupportFilePathResolver(Class<?> basePackageClass) {
        this(FileUtils.getPackageNameAsRelativePath(basePackageClass));
    }

    public SupportFilePathResolver(String baseFolderName) {
        this.baseSupportFileFolder = baseFolderName;
    }

    public static void setInstance(SupportFilePathResolver resolverInstance) {
        instance = resolverInstance;
    }

    public static SupportFilePathResolver getInstance() {
        if (instance == null) {
            instance = new SupportFilePathResolver();
        }
        return instance;
    }

    /**
     * Gets full path for specified file name. File must be in classpath. If a
     * base folder is set on the instance, will start search from specified base
     * folder.
     *
     * @param fileName
     *            name of file to find. can be prefixed with additional folder
     *            names. Use '/' (backslash) to separate directories
     * @return the file system file path. Throws RuntimeException if file is not
     *         in classpath.
     */
    public static String resolveSupportFilePath(String fileName) {
        return getInstance().getSupportFilePath(fileName);
    }

    /**
     * Gets full path for specified file name. File must be in classpath. If a
     * base folder is set on the instance, will start search from specified base
     * folder. Throws a RuntimeException if the file cannot be found in the
     * classpath.
     *
     * @param fileName
     *            name of file to find. can be prefixed with additional folder
     *            names. Use '/' (backslash) to separate directories
     * @return the file system file path. Throws RuntimeException if file is not
     *         in classpath.
     */
    public String getSupportFilePath(String fileName) {

        URL fileUrl = getFileURL(fileName);
        String filePath = new File(fileUrl.getFile()).getAbsolutePath();
        if (StringUtil.stringContains(filePath, "%")) {
            try {
                filePath = URLDecoder.decode(filePath, "UTF-8");
            } catch (UnsupportedEncodingException e) {
                e.printStackTrace();
            }
        }
        return filePath;
    }

    /**
     * Gets the URL for file in classpath, starting with base support folder.
     * File name should be a relative path, using directory separator character
     * to specify the path to the file, e.g. com/eztech/test/myfile.txt
     *
     * @param fileName
     * @return url of file
     */
    public URL getFileURL(String fileName) {
        if (baseSupportFileFolder != null) {
            fileName = baseSupportFileFolder + "/" + fileName;
        }
        LOG.info("getSupportFilePath(): trying to find URL for fileName=" + fileName);
        URL fileUrl = this.getClass().getClassLoader().getResource(fileName);
        if (fileUrl == null) {
            if (dumpClasspathOnError) {
                dumpClasspath();
            }
            throw new RuntimeException("Unable to locate resource with name=" + fileName);
        }
        return fileUrl;
    }

    private void dumpClasspath() {
        //Get the System Classloader
        ClassLoader sysClassLoader = ClassLoader.getSystemClassLoader();

        //Get the URLs
        URL[] urls = ((URLClassLoader) sysClassLoader).getURLs();
        System.err.println("Dumping classpath (SysClassLoader)...:");
        for (int i = 0; i < urls.length; i++) {
            System.err.println(urls[i].getFile());
        }

    }

}