A URL is the location of a resource, not necessarily a file system. The resource may not have the concept of a directory.
If the URL points to a file, you can just check if the file is a directory. If it points to a JAR, you have to open the JAR, get the corresponding entry, and see if it is a directory. Unfortunately, Java's zip API is quite crappy. I messed around and got the below. While it seems to work, I arrived at it by trial and error because the ZipEntry#isDirectory only seems to return true when the path ends in slash, and ZipFile#getInputStream returns null, and the javadocs don't even tell what the hell that means.
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| static public boolean isDirectory (URL url) throws IOException {
String protocol = url.getProtocol();
if (protocol.equals("file")) {
return new File(url.getFile()).isDirectory();
}
if (protocol.equals("jar")) {
String file = url.getFile();
int bangIndex = file.indexOf('!');
String jarPath = file.substring(bangIndex + 2);
file = new URL(file.substring(0, bangIndex)).getFile();
ZipFile zip = new ZipFile(file);
ZipEntry entry = zip.getEntry(jarPath);
boolean isDirectory = entry.isDirectory();
if (!isDirectory) {
InputStream input = zip.getInputStream(entry);
isDirectory = input == null;
if (input != null) input.close();
}
return isDirectory;
}
throw new RuntimeException("Invalid protocol: " + protocol);
} |
