MapStruct简单实例

简介

MapStruct 是一个开源的基于 Java 的代码生成器，用于创建实现 Java Bean 之间转换的扩展映射器。使用 MapStruct，我们只需要创建接口，而该库会通过注解在编译过程中自动创建具体的映射实现，大大减少了通常需要手工编写的样板代码的数量。

处理器选项

gradle依赖

// https://mvnrepository.com/artifact/org.mapstruct/mapstruct
implementation group: 'org.mapstruct', name: 'mapstruct', version: '1.4.2.Final'
annotationProcessor group: 'org.mapstruct', name: 'mapstruct-processor', version: '1.4.2.Final'

实体1

import lombok.Builder;
import lombok.Data;

@Data
@Builder
@AllArgsConstructor
@NoArgsConstructor
public class Doctor {
    private int id;
    private String name;
    private String specialty;
}

实体2

import lombok.Builder;
import lombok.Data;

@Data
@Builder
@AllArgsConstructor
@NoArgsConstructor
public class Education {
    private String degreeName;
    private String institute;
    private Integer yearOfPassing;
}

传输体

import lombok.Builder;
import lombok.Data;

@Data
@Builder
@AllArgsConstructor
@NoArgsConstructor
public class DoctorDTO {
    private int id;
    private String name;
    private String degree;
    private String specialization;
}

传输体Mapper

import org.mapstruct.Mapper;
import org.mapstruct.Mapping;
import org.mapstruct.factory.Mappers;
import org.mapstruct.ReportingPolicy;

@Mapper(unmappedTargetPolicy = ReportingPolicy.IGNORE)
public interface DoctorMapper {

    DoctorMapper INSTANCE = Mappers.getMapper(DoctorMapper.class);

    // 只有一个source类，也需要写source的类名
    // 同名不需要写Mapping映射
    @Mapping(source = "doctor.specialty", target = "specialization")
    @Mapping(source = "education.degreeName", target = "degree")
    DoctorDTO toDTO(Doctor doctor, Education education);
}

测试类

import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

@RequestMapping("/test")
@RestController
public class Test {


    @RequestMapping("/exec")
    public void exec() {
        Doctor doctor = Doctor.builder().id(1).name("test").specialty("111").build();
        Education education = Education.builder().degreeName("222").institute("333").yearOfPassing(2).build();
        DoctorDTO doctorDto = DoctorMapper.INSTANCE.toDTO(doctor, education);
        System.out.println(doctorDto.toString());
    }
}