Merge branch 'refs/heads/wepay-paysign' into container-test

liquidnet-bus-common/liquidnet-common-base/src/main/java/com/liquidnet/commons/lang/util/MD5Utils.java

 package com.liquidnet.commons.lang.util;
 
-import java.math.BigInteger;
 import java.nio.charset.Charset;
 import java.security.MessageDigest;
 import java.security.NoSuchAlgorithmException;
@@ -20,20 +19,13 @@ public class MD5Utils {
      * 使用md5的算法进行加密
      */
     public static String md5(String plainText) {
-        byte[] secretBytes = null;
         try {
-            secretBytes = MessageDigest.getInstance("md5").digest(plainText.getBytes(Charset.defaultCharset()));
+            byte[] secretBytes = MessageDigest.getInstance("md5").digest(plainText.getBytes(Charset.defaultCharset()));
+            // 不可使用 BigInteger.toString(16)：会吞掉高位为 0 的半字节/整字节，导致 MD5 非固定 32 位十六进制（微信二次签名会偶发失败）
+            return bufferToHex(secretBytes);
         } catch (NoSuchAlgorithmException e) {
             throw new RuntimeException("没有md5这个算法！");
         }
-        String md5code = new BigInteger(1, secretBytes).toString(16);// 16进制数字
-        // 如果生成数字未满32位，需要前面补0
-        if (md5code.length() < 32) {
-            for (int i = 0; i <= 32 - md5code.length(); i++) {
-                md5code = "0" + md5code;
-            }
-        }
-        return md5code;
     }
 
     protected static MessageDigest messagedigest = null;