feat：12月活动

mec-biz/src/main/java/com/ym/mec/biz/service/impl/StudentRegistrationServiceImpl.java

@@ -1443,12 +1443,8 @@ public class StudentRegistrationServiceImpl extends BaseServiceImpl<Long, Studen
             return BigDecimal.ZERO;
         }
 
-        if(amount.abs().compareTo(studentRegistration.getSurplusCourseFee())>0){
-            if(BigDecimal.ZERO.compareTo(amount)>0){
-                amount = studentRegistration.getSurplusCourseFee().negate();
-            }else{
-                amount = studentRegistration.getSurplusCourseFee();
-            }
+        if(BigDecimal.ZERO.compareTo(amount)>0&&amount.abs().compareTo(studentRegistration.getSurplusCourseFee())>0){
+            amount = studentRegistration.getSurplusCourseFee().negate();
         }
 
         studentRegistration.setSurplusCourseFee(studentRegistration.getSurplusCourseFee().add(amount));