【Java】实体类转换框架 MapStruct
简单尝试了下发现比Dozer还有BeanUtil还方便小巧
注解的作用是在生成字节码文件时实现具体GetterSetter方法，实际转换时就是赋值操作，嘎嘎快
参考文章：
https://juejin.cn/post/7140149801991012365
引入必须的依赖：
lombok一般项目都会添加，这里我就只放这两个
<dependency>
<groupId>org.mapstruct</groupId>
<artifactId>mapstruct</artifactId>
<version>1.5.0.Final</version>
</dependency>
<dependency>
<groupId>org.mapstruct</groupId>
<artifactId>mapstruct-processor</artifactId>
<version>1.5.0.Final</version>
</dependency>
一、入门案例：
两个需要相互转换的实体类，演示用：
DTO
package cn.cloud9.server.test.mapstruct;
import lombok.*;
import lombok.experimental.Accessors;
@Data
@Builder
@ToString
@Accessors(chain = true)
@AllArgsConstructor
@NoArgsConstructor
public class DemoDTO {
private Integer fieldA;
private Boolean fieldB;
private String fieldC;
}
Entity
package cn.cloud9.server.test.mapstruct;
import lombok.*;
import lombok.experimental.Accessors;
@Data
@Builder
@ToString
@Accessors(chain = true)
@AllArgsConstructor
@NoArgsConstructor
public class DemoEntity {
private Integer fieldD;
private Boolean fieldE;
private String fieldF;
}
转换器接口编写：
如果需要转换更多的实体类，都可以在接口声明方法，然后声明映射的字段
package cn.cloud9.server.test.mapstruct;
import org.mapstruct.Mapper;
import org.mapstruct.Mapping;
import org.mapstruct.Mappings;
import org.mapstruct.factory.Mappers;
/**
* 转换器接口
*/
@Mapper
public interface DemoConverter {
DemoConverter INSTANCE = Mappers.getMapper(DemoConverter.class);
/* DTO -> ENTITY */
@Mappings(value = {
@Mapping(source = "fieldA", target = "fieldD"),
@Mapping(source = "fieldB", target = "fieldE"),
@Mapping(source = "fieldC", target = "fieldF"),
})
DemoEntity dto2entity(DemoDTO demoDTO);
/* ENTITY -> DTO */
@Mappings(value = {
@Mapping(source = "fieldD", target = "fieldA"),
@Mapping(source = "fieldE", target = "fieldB"),
@Mapping(source = "fieldF", target = "fieldC"),
})
DemoDTO entity2dto(DemoEntity demoEntity);
}
测试方法：
@Test
public void converterTest() {
DemoDTO build = DemoDTO.builder()
.fieldA(1001)
.fieldB(Boolean.TRUE)
.fieldC("TEST")
.build();
DemoEntity demoEntity = DemoConverter.INSTANCE.dto2entity(build);
DemoDTO demoDTO = DemoConverter.INSTANCE.entity2dto(demoEntity);
log.info("demoEntity -> {}", demoEntity);
log.info("demoDTO -> {}", demoDTO);
}
执行结果：
22:52:20.079 [main] INFO cn.cloud9.spring.BeanFactoryTest - demoEntity -> DemoEntity(fieldD=1001, fieldE=true, fieldF=TEST) 22:52:20.083 [main] INFO cn.cloud9.spring.BeanFactoryTest - demoDTO -> DemoDTO(fieldA=1001, fieldB=true, fieldC=TEST) Process finished with exit code 0
二、集合转换支持
也是根据参数类型推断，自动生成了迭代集合
/* List<ENTITY -> DTO> */
@Mappings(value = {
@Mapping(source = "fieldD", target = "fieldA"),
@Mapping(source = "fieldE", target = "fieldB"),
@Mapping(source = "fieldF", target = "fieldC"),
})
List<DemoDTO> entity2dto(List<DemoEntity> demoEntity);
/* List<DTO -> ENTITY> */
@Mappings(value = {
@Mapping(source = "fieldA", target = "fieldD"),
@Mapping(source = "fieldB", target = "fieldE"),
@Mapping(source = "fieldC", target = "fieldF"),
})
List<DemoEntity> dto2entity(List<DemoDTO> demoDTO);
测试方法：
ArrayList<DemoDTO> objects = new ArrayList<>();
for (int i = 0; i < 10; i++) {
objects.add(DemoDTO.builder()
.fieldA(1001)
.fieldB(Boolean.TRUE)
.fieldC("TEST")
.build());
}
List<DemoEntity> demoEntityList = DemoConverter.INSTANCE.dto2entity(objects);
demoEntityList.forEach(d -> log.info("de {}", d));
执行结果：
23:16:13.845 [main] INFO cn.cloud9.spring.BeanFactoryTest - de DemoEntity(fieldD=1001, fieldE=true, fieldF=TEST) 23:16:13.845 [main] INFO cn.cloud9.spring.BeanFactoryTest - de DemoEntity(fieldD=1001, fieldE=true, fieldF=TEST) 23:16:13.845 [main] INFO cn.cloud9.spring.BeanFactoryTest - de DemoEntity(fieldD=1001, fieldE=true, fieldF=TEST) 23:16:13.845 [main] INFO cn.cloud9.spring.BeanFactoryTest - de DemoEntity(fieldD=1001, fieldE=true, fieldF=TEST) 23:16:13.845 [main] INFO cn.cloud9.spring.BeanFactoryTest - de DemoEntity(fieldD=1001, fieldE=true, fieldF=TEST) 23:16:13.845 [main] INFO cn.cloud9.spring.BeanFactoryTest - de DemoEntity(fieldD=1001, fieldE=true, fieldF=TEST) 23:16:13.845 [main] INFO cn.cloud9.spring.BeanFactoryTest - de DemoEntity(fieldD=1001, fieldE=true, fieldF=TEST) 23:16:13.845 [main] INFO cn.cloud9.spring.BeanFactoryTest - de DemoEntity(fieldD=1001, fieldE=true, fieldF=TEST) 23:16:13.845 [main] INFO cn.cloud9.spring.BeanFactoryTest - de DemoEntity(fieldD=1001, fieldE=true, fieldF=TEST) 23:16:13.845 [main] INFO cn.cloud9.spring.BeanFactoryTest - de DemoEntity(fieldD=1001, fieldE=true, fieldF=TEST)
三、映射配置继承与反向继承
只需要提供一份映射注解信息即可，其他方法通过继承注解获取映射信息
同理，要反向转换时，提供了一个反向注解：
两个注解都需要你提供方法名来查找映射配置
package cn.cloud9.server.test.mapstruct;
import org.mapstruct.*;
import org.mapstruct.factory.Mappers;
import java.util.List;
/**
* 转换器接口
*/
@Mapper
public interface DemoConverter {
DemoConverter INSTANCE = Mappers.getMapper(DemoConverter.class);
/* DTO -> ENTITY */
@Mappings(value = {
@Mapping(source = "fieldA", target = "fieldD"),
@Mapping(source = "fieldB", target = "fieldE"),
@Mapping(source = "fieldC", target = "fieldF"),
})
DemoEntity dto2entity(DemoDTO demoDTO);
/* ENTITY -> DTO */
// @Mappings(value = {
// @Mapping(source = "fieldD", target = "fieldA"),
// @Mapping(source = "fieldE", target = "fieldB"),
// @Mapping(source = "fieldF", target = "fieldC"),
// })
// DemoDTO entity2dto(DemoEntity demoEntity);
@InheritInverseConfiguration(name = "dto2entity")
DemoDTO entity2dto(DemoEntity demoEntity);
/* List<ENTITY -> DTO> */
// @Mappings(value = {
// @Mapping(source = "fieldD", target = "fieldA"),
// @Mapping(source = "fieldE", target = "fieldB"),
// @Mapping(source = "fieldF", target = "fieldC"),
// })
@InheritConfiguration(name = "entity2dto")
List<DemoDTO> entity2dto(List<DemoEntity> demoEntity);
/* List<DTO -> ENTITY> */
// @Mappings(value = {
// @Mapping(source = "fieldA", target = "fieldD"),
// @Mapping(source = "fieldB", target = "fieldE"),
// @Mapping(source = "fieldC", target = "fieldF"),
// })
@InheritInverseConfiguration(name = "entity2dto")
List<DemoEntity> dto2entity(List<DemoDTO> demoDTO);
}
四、是否阻止默认映射
默认同名同类型字段直接映射
这里对两个实体类新加了同一个字段：
private Long filedG;
测试时添加该属性：
@Test
public void converterTest() {
DemoDTO build = DemoDTO.builder()
.fieldA(1001)
.fieldB(Boolean.TRUE)
.fieldC("TEST")
.filedG(3003L)
.build();
DemoEntity demoEntity = DemoConverter.INSTANCE.dto2entity(build);
DemoDTO demoDTO = DemoConverter.INSTANCE.entity2dto(demoEntity);
log.info("demoEntity -> {}", demoEntity);
log.info("demoDTO -> {}", demoDTO);
}
执行结果可以发现，默认赋值上去了
23:34:51.780 [main] INFO cn.cloud9.spring.BeanFactoryTest - demoEntity -> DemoEntity(fieldD=1001, fieldE=true, fieldF=TEST, filedG=3003) 23:34:51.787 [main] INFO cn.cloud9.spring.BeanFactoryTest - demoDTO -> DemoDTO(fieldA=1001, fieldB=true, fieldC=TEST, filedG=3003) Process finished with exit code 0
使用@BeanMapping注解可以阻止这种赋值行为：
/**
* 转换器接口
*/
@Mapper
public interface DemoConverter {
DemoConverter INSTANCE = Mappers.getMapper(DemoConverter.class);
/* @BeanMapping(ignoreByDefault = true) 阻止MapStruct默认同名字段赋值行为 */
@BeanMapping(ignoreByDefault = true)
/* DTO -> ENTITY */
@Mappings(value = {
@Mapping(source = "fieldA", target = "fieldD"),
@Mapping(source = "fieldB", target = "fieldE"),
@Mapping(source = "fieldC", target = "fieldF"),
})
DemoEntity dto2entity(DemoDTO demoDTO);
/* ENTITY -> DTO */
@InheritInverseConfiguration(name = "dto2entity")
DemoDTO entity2dto(DemoEntity demoEntity);
/* List<ENTITY -> DTO> */
@InheritConfiguration(name = "entity2dto")
List<DemoDTO> entity2dto(List<DemoEntity> demoEntity);
/* List<DTO -> ENTITY> */
@InheritInverseConfiguration(name = "entity2dto")
List<DemoEntity> dto2entity(List<DemoDTO> demoDTO);
}
再次执行发现不再能够进行赋值处理了：
23:38:03.011 [main] INFO cn.cloud9.spring.BeanFactoryTest - demoEntity -> DemoEntity(fieldD=1001, fieldE=true, fieldF=TEST, filedG=null) 23:38:03.015 [main] INFO cn.cloud9.spring.BeanFactoryTest - demoDTO -> DemoDTO(fieldA=1001, fieldB=true, fieldC=TEST, filedG=null)
是否不继承@BeanMapping忽略默认映射的配置？
https://www.bilibili.com/video/BV1E5411n7HR?p=9
在视频中提到是不继承的，这里我加上了字段的赋值，并且调用反向转换的方法：
DemoDTO build = DemoDTO.builder()
.fieldA(1001)
.fieldB(Boolean.TRUE)
.fieldC("TEST")
.fieldG(3003L)
.build();
DemoEntity demoEntity = DemoConverter.INSTANCE.dto2entity(build);
demoEntity.setFieldG(3003L);
DemoDTO demoDTO = DemoConverter.INSTANCE.entity2dto(demoEntity);
log.info("demoEntity -> {}", demoEntity);
log.info("demoDTO -> {}", demoDTO);
可以从执行结果发现，实际上是没有赋值的，说明是继承了@BeanMapping的效果了
23:41:02.989 [main] INFO cn.cloud9.spring.BeanFactoryTest - demoEntity -> DemoEntity(fieldD=1001, fieldE=true, fieldF=TEST, fieldG=3003) 23:41:02.994 [main] INFO cn.cloud9.spring.BeanFactoryTest - demoDTO -> DemoDTO(fieldA=1001, fieldB=true, fieldC=TEST, fieldG=null) Process finished with exit code 0
五、注册成SpringBean
在前面的用法中都是直接声明一个单例使用，这里可以交给Spring处理：
@Mapper(componentModel = "spring")
package cn.cloud9.server.test.mapstruct;
import org.mapstruct.*;
import org.mapstruct.factory.Mappers;
import java.util.List;
/**
* 转换器接口
*/
@Mapper(componentModel = "spring")
public interface DemoConverter {
DemoConverter INSTANCE = Mappers.getMapper(DemoConverter.class);
/* @BeanMapping(ignoreByDefault = true) 阻止MapStruct默认同名字段赋值行为 */
// @BeanMapping(ignoreByDefault = true)
/* DTO -> ENTITY */
@Mappings(value = {
@Mapping(source = "fieldA", target = "fieldD"),
@Mapping(source = "fieldB", target = "fieldE"),
@Mapping(source = "fieldC", target = "fieldF"),
})
DemoEntity dto2entity(DemoDTO demoDTO);
/* ENTITY -> DTO */
@InheritInverseConfiguration(name = "dto2entity")
DemoDTO entity2dto(DemoEntity demoEntity);
/* List<ENTITY -> DTO> */
@InheritConfiguration(name = "entity2dto")
List<DemoDTO> entity2dto(List<DemoEntity> demoEntity);
/* List<DTO -> ENTITY> */
@InheritInverseConfiguration(name = "entity2dto")
List<DemoEntity> dto2entity(List<DemoDTO> demoDTO);
}
在需要调用的地方声明即可：
package cn.cloud9.server.test.controller;
import cn.cloud9.server.test.mapstruct.DemoConverter;
import cn.cloud9.server.test.mapstruct.DemoDTO;
import cn.cloud9.server.test.mapstruct.DemoEntity;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import javax.annotation.Resource;
@RestController
@RequestMapping("/test/map-struct")
public class MapStructController {
@Resource
private DemoConverter demoConverter;
@GetMapping("/get")
public DemoEntity converterTest() {
DemoDTO build = DemoDTO.builder()
.fieldA(1001)
.fieldB(Boolean.TRUE)
.fieldC("TEST")
.fieldG(3003L)
.build();
return demoConverter.dto2entity(build);
}
}
测试结果：
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