将MessageDigest与J2ME应用程序一起使用

Question

I'm unable to use the MessageDigest API in a J2ME application - it is giving ALERT NoSuchMethodError

digest()

My code is

MessageDigest md= MessageDigest.getInstance("SHA-1");         
md.update(hashString.getBytes("UTF-8"),0,0);
byte[] digest = null;
md.digest(digest,0,digest.length);
System.out.println("digest of str is "+new String(digest) );

The above code works fine in a Java application, but gives NoSuchMethodError in J2ME.

Can I use MessageDigest in J2ME? If yes , please tell me how.

Answer 1

java.security.MessageDigest is not generally part of J2ME, so it's not directly available.

There are some J2ME devices that implement JSR 177 , which would allow you to use MessageDigest .

Or, you could try an open source SHA1 implementation, such as this one .

Another alternative would be to use the BouncyCastle library, and use it to implement SHA1 digests for J2ME .

If you use BouncyCastle, make sure to get one of the releases (.jar or source code) that's designed for J2ME .