参数排序，生成md5的sign

import java.io.UnsupportedEncodingException;
import java.net.URLEncoder;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class HashUtils {

    private static final char[] HEX_CHARS = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e',
            'f' };

    public static char[] encodeHex(byte[] bytes) {
        char[] chars = new char[32];
        for (int i = 0; i < chars.length; i += 2) {
            byte b = bytes[(i / 2)];
            chars[i] = HEX_CHARS[(b >>> 4 & 0xF)];
            chars[(i + 1)] = HEX_CHARS[(b & 0xF)];
        }
        return chars;
    }

    public static MessageDigest getDigest(String algorithm) {
        try {
            return MessageDigest.getInstance(algorithm);
        } catch (NoSuchAlgorithmException ex) {
            throw new IllegalStateException("Could not find MessageDigest with algorithm "" + algorithm + """, ex);
        }
    }

    public static String md5(String src) {
        MessageDigest md5 = getDigest("MD5");
        return new String(encodeHex(md5.digest(src.getBytes())));
    }

    public static String toSign(Map<String,Object> map) {
        
        return "";
    };
    
    public static String getFormatParams(Map<String, Object> params,boolean flag) throws UnsupportedEncodingException {
         List<Map.Entry<String, Object>> infoIds =
                 new ArrayList<Map.Entry<String, Object>>((Collection<? extends Entry<String, Object>>) params.entrySet());
            Collections.sort(infoIds, new Comparator<Map.Entry<String, Object>>() {
                public int compare(Map.Entry<String, Object> arg0, Map.Entry<String, Object> arg1) {
                    return (arg0.getKey()).compareTo(arg1.getKey());
                }
            });
            String ret = "";

            for (Map.Entry<String, Object> entry : infoIds) {
                ret += entry.getKey();
                ret += "=";
                if(flag) {
                    if(generateJudgment(entry.getValue().toString())) {
                        ret +=URLEncoder.encode(entry.getValue().toString(), "UTF-8") ;
                    }else {
                        ret += entry.getValue().toString();
                    }
                }else {
                    ret += entry.getValue().toString();
                }
                ret += "&";
            }
            ret = ret.substring(0, ret.length() - 1);
            return ret;
    }
    
    //判断是否有汉字
    public static boolean generateJudgment(String countname){
         Pattern p = Pattern.compile("[u4e00-u9fa5]");
         Matcher isNum = p.matcher(countname);
         if (isNum.find()) {
            return true;
         }
         return false;
    }
    
    public static void main(String[] args) {
        String stringToSign = "B856915E" + "57C8666D91C346D1A23C766A4B8EDA85" + "1584338529869";
        System.out.println(md5(stringToSign));
    }

}