java实现HMACSHA256加密签名，需要按照字典排序的朋友可以用
SortedMap<Object, Object> message=new TreeMap<Object, Object>();进行排序后在加密。


/**

* @version 1.0
* @project： autoTrade 
* @author： QC班长 
* @date：2017/8/3 
* @time：10:17 
*/

import javax.crypto.Mac;
import javax.crypto.spec.SecretKeySpec;
import java.util.*;
public class HMACSHA256 { 
 //   SECRET KEY    
 private final static String secret_key = "ndE2jdZNFixH9G6Aidsfyf7lYT3PxW";  
  /**     
  * 将加密后的字节数组转换成字符串   
  *    
  * @param b 字节数组    
  * @return 字符串     
  */   
 private static String byteArrayToHexString(byte[] b) {  
      StringBuilder hs = new StringBuilder();     
      String stmp;      
  for (int n = 0; b!=null && n < b.length; n++) {   
         stmp = Integer.toHexString(b[n] & 0XFF);    
         if (stmp.length() == 1)           
         hs.append('0');      
         hs.append(stmp);    
    }      
   return hs.toString().toLowerCase();   
 }   

 /**   
  * sha256_HMAC加密    
  * @param message 消息   
  * @param secret  秘钥 
  * @return 加密后字符串  
  */  
  private static String sha256_HMAC(String message, String secret) {     
   String hash = "";      
   try {         
       Mac sha256_HMAC = Mac.getInstance("HmacSHA256");     
       SecretKeySpec secret_key = new SecretKeySpec(secret.getBytes(), "HmacSHA256");      
       sha256_HMAC.init(secret_key);       
       byte[] bytes = sha256_HMAC.doFinal(message.getBytes());   
       hash = byteArrayToHexString(bytes);         
       System.out.println(hash);    
       } catch (Exception e) {     
       System.out.println("Error HmacSHA256 ===========" + e.getMessage());   
     }       
    return hash;   
   }     
 }