fix bug

@@ -41,6 +41,9 @@ public class BrandNameUtils {
     }
 
     private static String genBrandNameForSort(String brandName) {
+        if(StringUtils.isBlank(brandName)){
+            return null;
+        }
         StringBuilder brandNameForSort = new StringBuilder();
         for (int i = 0; i < brandName.length(); i++) {
             String brandNamePart = brandName.substring(i, i + 1);
@@ -74,7 +77,7 @@ public class BrandNameUtils {
      * @param chinese
      * @return
      */
-    public static String chineseToPinyin(String chinese) {
+    private static String chineseToPinyin(String chinese) {
         try {
             // 创建汉语拼音处理类
             HanyuPinyinOutputFormat defaultFormat = new HanyuPinyinOutputFormat();