Reading from jar file from classpath

I had a recent issue with "read all the files in folder from within the jar file that is in the class path". The standard solution is generate a resources file (in this case include all the files) and set it to a known location in the jar file. Then access the resource file, read the names and load the files from the stream.

I did it this way:

public class ZipFileUtil {

/**

* Lowercase extension names for zip or zipish files.

*/

private static final String[] zipExtensions = { ".zip", ".jar" };

/**

* Name of system property for java class path.

*/

private static final String CLASS_PATH_PROPERTY_NAME = "java.class.path";

/**

* Search the class path for a file name.

*

* This is slower if not case sensitive.

*

* @param fileName the file name

* @param caseSensitive the match for file name will be case sensitive

* @return a File or null if not found or if this isn't a zip (or zipish) file.

*/

public static File getFileFromJar(String fileName, final boolean caseSensitive) {

if (!isJarFile(fileName)) {

return null;

}

fileName = fileName.trim();

File rVal = null;

final String fullPath = System.getProperties().getProperty(CLASS_PATH_PROPERTY_NAME);

final String[] jars = fullPath.split(File.pathSeparator);

if (jars != null) {

for (String jarName : jars) {

jarName = jarName.trim();

if (jarName.endsWith(fileName) || (!caseSensitive && jarName.toLowerCase().endsWith(fileName.toLowerCase()))) {

return new File(jarName);

}

}

}

return rVal;

}

/**

* List all the file names contained in a jar/zip file.

*

* @param jarFile the jar/zip file to search

* @param target pattern to match (no wildcards)

* @return list of strings that are relative filenames that match the target pattern or null if this isn't a zip (or zipish) file.

* @throws IOException if an exception occurs

*/

public static List listMatchingContents(final File jarFile, final String target) throws IOException {

if (!isJarFile(jarFile)) {

return null;

}

final List rVal = new ArrayList();

ZipInputStream zis = new ZipInputStream(new FileInputStream(jarFile));

for (ZipEntry ze = zis.getNextEntry(); ze != null; ze = zis.getNextEntry()) {

if (ze.getName().indexOf(target) > -1) {

rVal.add(ze.getName());

}

}

return rVal;

}

/**

* List all the file names contained in a jar/zip file.

*

* @param jarFilename the name of jar/zip file to search

* @param target pattern to match (no wildcards)

* @return list of strings that are relative filenames that match the target pattern or null if this isn't a zip (or zipish) file.

* @throws IOException if an exception occurs

*/

public static List listMatchingContents(final String jarFilename, final String target) throws IOException {

return listMatchingContents(new File(jarFilename), target);

}

/**

* Is this a zip file?.

*

* @param aFilename a file name

* @return true of false (true for yes it is a zipish file)

*/

public static boolean isJarFile(String aFilename) {

if (aFilename == null || aFilename.trim().length() == 0) {

return false;

}

aFilename = aFilename.trim().toLowerCase();

for (String anExtension : zipExtensions) {

if (aFilename.endsWith(anExtension)) {

return true;

}

}

return false;

}

/**

* Is this a zip file?.

*

* @param aFile a file

* @return true of false (true for yes it is a zipish file)

*/

public static boolean isJarFile(final File aFile) {

if (aFile == null) {

return false;

}

return isJarFile(aFile.getName());

}

}