快速开始

引入pom依赖

我的项目使用了lombok，将lombok和mapstruct配合使用。

<dependency>
    <groupId>org.mapstruct</groupId>
    <artifactId>mapstruct</artifactId>
    <version>1.4.1.Final</version>
</dependency>
<dependency>
    <groupId>org.mapstruct</groupId>
    <artifactId>mapstruct-processor</artifactId>
    <version>1.4.1.Final</version>
</dependency>
<dependency>
    <groupId>org.projectlombok</groupId>
    <artifactId>lombok</artifactId>
    <version>1.18.12</version>
</dependency>
<plugin>
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-compiler-plugin</artifactId>
    <version>3.8.1</version>
    <configuration>
       <source>1.8</source>
       <target>1.8</target>
       <encoding>UTF-8</encoding>
       <annotationProcessorPaths>
           <path>
               <groupId>org.mapstruct</groupId>
               <artifactId>mapstruct-processor</artifactId>
               <version>${mapstruct.version}</version>
           </path>
           <path>
               <groupId>org.projectlombok</groupId>
               <artifactId>lombok</artifactId>
               <version>${lombok.version}</version>
           </path>
           <!-- other annotation processors -->
       </annotationProcessorPaths>
    </configuration>
</plugin>

创建entity和dto

@Data
@NoArgsConstructor
@AllArgsConstructor
public class Car {
    private String make;
    private Integer numberOfSeats;
    private Integer type;
}
@Data
public class CarDto {
    private String make;
    private int seatCount;
    private String type;
}

声明mapper接口

转换规则

字段类型和名称一致，无需映射
名称不一致需要映射

名称一致类型不一致的情况需要看下mapstruct支不支持，不支持需要自定义转换器

@Mapper
public interface CarMapper {
  CarMapper INSTANCE = Mappers.getMapper(CarMapper.class);
  @Mapping(source = "numberOfSeats", target = "seatCount")
  CarDto carToCarDto(Car car);
}

执行转换

public class CarTest {
  @Test
  public void test_converter() {
      //given
      Car car = new Car("Morris", 5, 10);
      //when
      CarDto carDto = CarMapper.INSTANCE.carToCarDto(car);
      //then
      System.out.println(carDto.getMake());
      System.out.println(carDto.getSeatCount());
      System.out.println(carDto.getType());
  }
}

结合DDD

在父pom引入依赖声明，client引入jar包

dto和entity转换

```java public interface Assembler { /**

将entity转为dto *
@param entity 领域实体
@return dto */ Dto convertToDto(Entity entity);

/**
将dto转为entity *
@param dto 数据传输对象
@return 领域实体 */ Entity convertToEntity(Dto dto); }

@Mapper(uses = DateMapper.class) public interface DictDetailAssembler extends Assembler { DictDetailAssembler INSTANCE = Mappers.getMapper(DictDetailAssembler.class);

@Mappings({@Mapping(source = "id", target = "seqNo"),
        @Mapping(source = "dictName", target = "name"),
        @Mapping(source = "dictType", target = "type"),
        @Mapping(source = "createTime", target = "createTime")})
DictDetailItem convertToDto(DictDetail dictDetail);
@Mappings({@Mapping(source = "seqNo", target = "id"),
        @Mapping(source = "name", target = "dictName"),
        @Mapping(source = "type", target = "dictType")})
DictDetail convertToEntity(DictDetailItem dictDetailItem);

}

<a name="fAXE8"></a>
## DO和entity转换
```java
public interface Converter<DO, Entity> {
    /**
     * 将entity转为DO
     *
     * @param entity 领域实体
     * @return dto
     */
    DO convertToDO(Entity entity);
    /**
     * 将DO转为entity
     *
     * @param Do 数据库传输对象
     * @return 领域实体
     */
    Entity convertToEntity(DO Do);
}
@Mapper
public interface DictDetailConverter extends Converter<DictDetailDO, DictDetail> {
    DictDetailConverter INSTANCE = Mappers.getMapper(DictDetailConverter.class);
    DictDetailDO convertToDO(DictDetail dictDetail);
    DictDetail convertToEntity(DictDetailDO dictDetailDO);
}

自定义转换器

比如有个entity的createTime是timetamp类型的，dto的createTime是string类型的，直接映射会报错的

添加转换器

public class DateMapper {
    public String asString(Date date) {
        return date != null ? new SimpleDateFormat(QmsConstant.YYYYMMDDHHMMSS)
                .format(date) : null;
    }
    public Date asDate(String date) {
        try {
            return date != null ? new SimpleDateFormat(QmsConstant.YYYYMMDDHHMMSS)
                    .parse(date) : null;
        } catch (ParseException e) {
            throw new RuntimeException(e);
        }
    }
}

mapper声明转换器

uses是数组可以声明多个

@Mapper(uses = DateMapper.class)

MapStruct使用