DTOs mappers 4 commons ways

1. MapStruct

• Description: MapStruct is a popular code generation library that automates the creation of mapping code at compile time. It generates type-safe mappers with little to no overhead, as it doesn’t use reflection or runtime processing.
• Usage: Define interfaces for mappings, and MapStruct generates the implementation.
• Pros: Very efficient (no runtime overhead), strongly typed, supports nested mappings, and allows custom mappings.
• Example:

@Mapper(componentModel = "spring")
public interface OrderMapper {
    OrderMapper INSTANCE = Mappers.getMapper(OrderMapper.class);
    OrderDTO toDto(Order order);
    Order toEntity(OrderDTO dto);
}

• Dependency:

<dependency>
    <groupId>org.mapstruct</groupId>
    <artifactId>mapstruct</artifactId>
    <version>LATEST</version>
</dependency>

2. ModelMapper

• Description: ModelMapper is a powerful, flexible, and easy-to-use mapping library that handles complex object mappings.
• Usage: ModelMapper uses reflection to map properties automatically, making it a good choice for prototyping or simple mappings. It can also be configured for advanced scenarios, such as nested mappings.
• Pros: Simple to set up, supports conventions, and allows for configuration of complex mappings.
• Cons: Uses reflection, which can affect performance slightly more than compile-time mapping.
• Example:

ModelMapper modelMapper = new ModelMapper();
OrderDTO orderDTO = modelMapper.map(order, OrderDTO.class);

• Dependency:

<dependency>
    <groupId>org.modelmapper</groupId>
    <artifactId>modelmapper</artifactId>
    <version>LATEST/version>
</dependency>

3. Dozer

• Description: Dozer is another object-to-object mapping framework that supports deep copying and complex mappings.
• Usage: Useful for more complex or nested objects where manual mapping would be tedious. Dozer can be configured using XML or annotations to manage mappings.
• Pros: Flexible configuration options, handles complex mappings, supports recursive mapping.
• Cons: Uses reflection, which can slow down performance compared to MapStruct.
• Example:

Mapper mapper = new DozerBeanMapper();
OrderDTO orderDTO = mapper.map(order, OrderDTO.class);

• Dependency:

<dependency>
    <groupId>net.sf.dozer</groupId>
    <artifactId>dozer</artifactId>
    <version>LATEST</version>
</dependency>

4. Spring’s BeanUtils or ObjectMapper (Basic Reflection-Based Mapping)

• Description: Spring provides basic utilities for mapping with BeanUtils.copyProperties(), or you can use Jackson’s ObjectMapper to map objects to other types.
• Usage: These methods are quick solutions when you need simple mappings or JSON handling, though they aren’t as flexible as dedicated mappers.
• Pros: No additional dependencies if using Spring’s or Jackson’s built-in tools; quick and convenient for small mappings.
• Cons: Limited in customization and unsuitable for complex mappings or nested structures.
• Example:

// Spring’s BeanUtils
BeanUtils.copyProperties(sourceObject, targetObject);

// Jackson ObjectMapper
ObjectMapper objectMapper = new ObjectMapper();
OrderDTO orderDTO = objectMapper.convertValue(order, OrderDTO.class);

• Dependency (for Jackson’s ObjectMapper, which is often already included in Spring Boot):

<dependency>
    <groupId>com.fasterxml.jackson.core</groupId>
    <artifactId>jackson-databind</artifactId>
    <version>LATEST</version>
</dependency>

Choosing the Right Mapper

• MapStruct: Best for high-performance applications with complex mappings that benefit from compile-time checking.
• ModelMapper: Good for quick, flexible mapping with less setup; ideal for simpler use cases.
• Dozer: Useful for complex, deep mappings in more legacy setups.
• Spring’s BeanUtils/ObjectMapper: Convenient for quick, one-off mappings or when performance and complexity are not major concerns.

Links:

• JPA & Hibernate: Effective Query
• Key features of Java 8 ... 21 release
• Contact me