public static boolean isZip(final File file) {
		FileInputStream fis = null;
		try {
			fis = new FileInputStream(file);
			final byte[] m = new byte[4];
			fis.read(m);
			fis.close();
			return (m[0] << 24 | m[1] << 16 | m[2] << 8 | m[3]) == 0x504b0304;
		} catch (final IOException ignored) {
		} finally {
			if (fis != null) {
				try {
					fis.close();
				} catch (final IOException ignored) {
				}
			}
		}
		return false;
	}