Blood cases caused by Lombok use

brief introduction

because Lombok Convenience of annotation , Now entity classes are all used Lombok annotation .

Which is used in the entity class Lombok Notes mainly include the following ：

@Data 

Annotations in

class

On ; Providing all properties of the class  get  and  set  Method , It also provides equals、canEqual、hashCode、toString  Method .

@Setter

Annotations in

attribute

On ; Provide... For a single property set Method ;  Annotations in

class

On , Provide... For all properties of this class  set  Method .

@Getter

Annotations in

attribute

On ; Provide... For a single property  get  Method ;  Annotations in

class

On , Provide... For all properties of this class get Method .

@EqualsAndHashCode

Annotations in

class

On ,  Can generate  equals、canEqual、hashCode  Method .

@ToString

This annotation is used for

class

On , Can generate all parameters of  toString  Method .

@Data Annotations contain the functions of other annotations . In general , Use it directly @Data Realization .

@Builder

Use builder mode to build entity objects , Can only be annotated on classes , A chain construction factory that will generate a current process of the class .

@NoArgsConstructor

Generate a parameterless constructor

@AllArgsConstructor

The construction method that generates all parameters for all attributes in the entity .

If this annotation is applied , Must be used at the same time NoArgsConstructor Generate a parameterless constructor .

Java It is clearly stated in , When there is no constructor defined in a class , By default, the system provides a parameterless construction method for this class , This constructor is called the default constructor . When a class explicitly defines the constructor , Then the system will no longer provide a default constructor for this class by default . Development must manually provide a parameterless constructor for the current class , Because parameterless construction methods are very common .

Problem description

Online problems are caused by Lomkob Improper use of annotations . After the system goes online today , It is found that interface access often times out . The troubleshooting found that an exception occurred when calling the order center interface , This function is to judge whether the user has a corresponding type of order . The corresponding interface request entity classes are as follows ：

@Data
@Builder
@NoArgsConstructor
@AllArgsConstructor
public class OrderQueryReq {

 /**
 *  user id
 */
 private Long userId;
 /**
 *  Number of entries per page
 */
 private Integer pageSize = 1;

 /**
 *  Course type
 */
 private String courseType;

 /**
 *  The order status
 */
 private String status;

 /**
 *  Payment time ends
 */
 private String payEndTime;
}

The corresponding entity class defaults to pageSize by 1. But in the process of screening , It is found that there is no pageSize attribute .

 PageResp<OrderResp> orderPage = orderCenterAgent.getOrder(OrderQueryReq.builder()
 .userId(userId).payEndTime(DateUtil.timeToString(payTime)).courseType(courseType)
 .status(orderStatus).build());

Request the Builder The builder builder provided by the annotation .

however class File decompiled Builder There is no pageSize The default value is

So there is no object constructed pageSize Parameters .

Cause analysis

The business function is only to judge whether the user has a corresponding type of order . Because there is no transmission PageSize Parameters , Query all orders of this type for this user . Because some users have large orders , Therefore, there will be a timeout problem in the query process .

resolvent

Lombok In the use of @Builder when , Member variables are not set to default . Can be set by

@Builder.Default

After the note , Use the ID to determine whether the default value is enabled .

On the attribute field that needs to set the default value , Add @Builder.Default annotation

Generated after compilation Class as follows ：

In Builder build When , It will determine whether to assign values to the fields with this annotation . without , Then use the initial default value of the field in the entity object .

The interface timeout problem is solved .