java Md5加密

public class SecurityMD5
{
    public static String Md5OfStr(String plainText)
    {
        String md5Str = "";
        try
        {
            MessageDigest md = MessageDigest.getInstance("MD5");
            md.update(plainText.getBytes());
            byte b[] = md.digest();
            int i;
            StringBuffer buf = new StringBuffer("");
            for(int offset = 0; offset < b.length; offset++)
            {
                i = b[offset];
                if(i < 0)
                {
                    i += 256;
                }
                if(i < 16)
                {
                    buf.append("0");
                }
                buf.append(Integer.toHexString(i));
            }
//                System.out.println("result: " + buf.toString());// 32位的加密
            md5Str = buf.toString().substring(8, 24);// 16位的加密
        } catch(NoSuchAlgorithmException e)
        {
            e.printStackTrace();
        }
        return md5Str;
    }
}