java md5加密 不依赖base64包

/**
 * MD5 加密
 */
private String getMD5Str(String str) {
	MessageDigest messageDigest = null;  

	try {
		messageDigest = MessageDigest.getInstance("MD5");  

		messageDigest.reset();  

		messageDigest.update(str.getBytes("UTF-8"));
	} catch (NoSuchAlgorithmException e) {
		System.out.println("NoSuchAlgorithmException caught!");
	} catch (UnsupportedEncodingException e) {
		e.printStackTrace();
	}  

	byte[] byteArray = messageDigest.digest();  

	StringBuffer md5StrBuff = new StringBuffer();  

	for (int i = 0; i < byteArray.length; i++) {
		if (Integer.toHexString(0xFF & byteArray[i]).length() == 1)
			md5StrBuff.append("0").append(Integer.toHexString(0xFF & byteArray[i]));
		else
			md5StrBuff.append(Integer.toHexString(0xFF & byteArray[i]));
	}  

	return md5StrBuff.toString();
}

转摘自：http://warren.iteye.com/blog/107386