package org.ithinking.utils;

import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
//消息摘要的輔助類,提供了MD5和SHA-1兩種摘要算法
public class MessageDigestUtil {

	private MessageDigest currentAlorithm=null;
	public static final String MD5="MD5";
	public static final String SHA1="SHA-1";
	public MessageDigestUtil(String method)
	{
		try
		{
		currentAlorithm=MessageDigest.getInstance(method);
		}
		catch(NoSuchAlgorithmException e)
		{
			e.printStackTrace();
			currentAlorithm=null;
		}
	}
	public byte[] computeDigest(byte[] b)
	{
		if(currentAlorithm==null)
			return null;
		currentAlorithm.reset();
		currentAlorithm.update(b);
		byte[] hash=currentAlorithm.digest();
		return hash;
	}
	public byte[] computeDigest(String s)
	{
		
		return computeDigest(s.getBytes());
	}
}