for a plaintext, for security, sometimes we need to do MD5 encryption, the following provides a Java tool method, directly called.

/**
 * MD5加密
 */
public class MD5Util {

	/**
	 * Encodes a string 2 MD5
	 * 
	 * @param str String to encode
	 * @return Encoded String
	 * @throws NoSuchAlgorithmException
	 */
	public static String crypt(String str) {
		if (str == null || str.length() == 0) {
			throw new IllegalArgumentException("String to encript cannot be null or zero length");
		}
		StringBuffer hexString = new StringBuffer();
		try {
			MessageDigest md = MessageDigest.getInstance("MD5");
			md.update(str.getBytes());
			byte[] hash = md.digest();
			for (int i = 0; i < hash.length; i++) {
				if ((0xff & hash[i]) < 0x10) {
					hexString.append("0" + Integer.toHexString((0xFF & hash[i])));
				} else {
					hexString.append(Integer.toHexString(0xFF & hash[i]));
				}
			}
		} catch (NoSuchAlgorithmException e) {
			e.printStackTrace();
		}
		return hexString.toString();
	}

}