【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: