kangwei：修改计算工具类

@@ -38,7 +38,7 @@ public class JSUtils {
         return executeExpression(expression,"0.00");
     }
     public static String divide(Object obj1 , Object obj2){
-        if(StringUtils.isNotEmpty(obj1.toString())){
+        if(obj1!= null && obj2!=null && StringUtils.isNotEmpty(obj1.toString())){
             if(StringUtils.isNotEmpty(obj2.toString()) && Double.parseDouble(obj2.toString())!=0){
                 String expression =  obj1+ "/" + obj2;
                 return executeExpression(expression,"0.00");