md5增加指定的加密规则，进行加密

import java.io.UnsupportedEncodingException;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

import org.springframework.util.StringUtils;

public class MD5 {
    private static final String ALGORITHM = "MD5";

    public MD5() {

    }

    /**md5的UTF-8编码加密.
    * @param text 待加密的文本
    * @return 加密后统一转成大写的文本
    * @version v1.0.0
     */
    public static String encrypt(String text) {
        byte[] hash;
        try {
            MessageDigest digest = MessageDigest.getInstance(ALGORITHM);
            hash = digest.digest(text.getBytes("UTF-8"));
        } catch (NoSuchAlgorithmException e) {
            e.printStackTrace();
            return null;
        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
            return null;
        }
        StringBuilder hex = new StringBuilder(hash.length * 2);
        for (byte b : hash) {
            if ((b & 0xFF) < 0x10)
                hex.append("0");
            hex.append(Integer.toHexString(b & 0xFF));
        }
        String md5 = hex.toString();
        md5 = md5.toUpperCase();
        return md5;
    }

    /**md5的UTF-8编码加密.
    * @param text 待加密的文本
    * @param key 校验字符串
    * @return 加密后统一转成大写的文本
    * @version v1.0.0
     */
    public static String encrypt(String text, String key) {
       if(StringUtils.isEmpty(key)){
           return null;
       }
       return encrypt(new StringBuilder(text).append(key).toString());
    }

    public static void main(String args[]) {
        System.out.println(encrypt("中国", "123"));
        System.out.println(encrypt("12345611"));
        System.out.println(encrypt("123456","11"));
    }
}