question: public static final String hashKeyForDisk ( final String key ) { String cacheKey ; try { final MessageDigest digest = MessageDigest . getInstance ( "MD5" ) ; digest . update ( key . getBytes ( ) ) ; cacheKey = bytesToHexString ( digest . digest ( ) ) ; } catch ( final NoSuchAlgorithmException e ) { cacheKey = String . valueOf ( key . hashCode ( ) ) ; } return cacheKey ; }
target:  A hashing method that changes a string (like a URL) into a hash suitable for using as a disk filename.