Java 生成16/32位 MD5

private static final char HEX_DIGITS[] = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F' };

private static String toHexString(byte[] b) {
StringBuilder sb = new StringBuilder(b.length * 2);
for (int i = 0; i < b.length; i++) {
sb.append(HEX_DIGITS[(b[i] & 0xf0) >>> 4]);
sb.append(HEX_DIGITS[b[i] & 0x0f]);
}
return sb.toString();
}

public static String Bit32(String SourceString) throws Exception {
MessageDigest digest = java.security.MessageDigest.getInstance("MD5");
digest.update(SourceString.getBytes());
byte messageDigest[] = digest.digest();
return toHexString(messageDigest);
}

public static String Bit16(String SourceString) throws Exception {
return Bit32(SourceString).substring(8, 24);
}