How to Use MapStruct with Lombok’s Builder

AjilAnto | Nov 02 2022

Are you still leaving your office late at night or stuck on an existing project by spending valuable time writing boilerplate codes for bean mapping in your powerful multi-layered architecture application? Now, it is time for you to master a new magic spell, which can help you reduce the time that is being wasted by writing many boilerplate codes for bean mapping. Let me introduce MapStruct,Apowerful annotation processor provided by Java. Which helps you to reduce the amount of extra boilerplate code for bean mapping.As of now, MapStruct version 1.5.2 final is the very latest version, which was released on June 18, 2022. It is possible to integrate it with the Lombok Builder pattern for better performance.

Generator Libraries Required

● Lombok isAutomatic Resource Management, automatic generation of getters, setters, equals, hash Code and to String, and more.

● MapStruct is a code generator that greatly simplifies the implementation of mappings between Java bean types based on a convention over configuration approach. These simple snippets of code will make you aware of how these two libraries work hand in hand in the way MapStruct implements Lombok’s builder methods. Implementing the Lombok builder

which will help us to make our code bug-free and maintenance-free.And which will increase the overall quality of the code by reducing unwanted lines of code.

Step 1: If you are using the maven project, make these necessary changes in the pom.xml.

If you are using the Gradle project make changes in the build. Gradle.

Step 2: After making changes in properties, we need to add a couple of dependencies.

Working

ToAchieve MapStruct functionality, we need to create an Interface, which will act as a bridge between the POJOs consisting of @mapper annotation. (@mapper: this annotation tells the MapStruct to generate an implementation class for the given interface).

Consider an example, where we create an entity named as ProductDetails and a ProductResponseDTO and we want to map the fields between them. Compared to other mapping frameworks, MapStruct provides us with the following benefits.

Step 3: Configure the maven-compile plugin to auto-generate implementations with the maven command.

1. Instead of reflection MapStruct provides fast execution by using plain method invocations.

2. This provides compile-time type safety The objects and attributes which share mapping can only be mapped using a MapStruct.

3. MapStruct provides clear build-time reports if any occurred while the time of compiling.

ProductDetails.java

ProductResponseDTO.java

To achieve mapping between the fields in both java classes we need to create an interface that has been mentioned above that consists of @mapper annotation.And we specify the input and the output.

ProductMapper

After doing these many steps we need to compile the maven.

When these steps are completed, a new class is generated ProductMapperImpl. Which can be found under the target folder

ProductMapperImpl

For

Mapping,

the list of entities

Considering that list of items was there inside the ProductDetails and we want to convert it into ProductResponseDTO we need to configure our mapper interface with new methods as shown in the figure.

After configuring the mapper interface compile the maven as we did before.And follow the previous steps.

ProductResponseDTO

After successfully creating these two entities as we did in the previous case, configure the mapper interface with an extra annotation called @Mapping.

If we need to define the field which differs in both entities.

● Source: source contains the name we have given inside the input entity

● Target: target contains the name we have given inside the output entity

ProductMapper

In this world, everyone is in hurry and we need some new measures to complete our tasks in the prescribed time without making any further lag in the projects which we are handling. If you are an ITprofessional or student who cares more about an ITcareer, I would surely recommend mastering the MapStruct which will make your way faster and better.

Thanks for reading! In this blog, we tried to convey a basic introduction to MapStruct and we expect all of you to understand what we tried to convey. If you run into any trouble or need assistance with MapStruct, get in touch with us.