ModelMapper 的高级使用

快来打我* 2022-02-02 14:39 226阅读 0赞

## ModelMapper 高级使用 ##

ModelMapper 是一个 Object To Object 的工具，类似于 MapStruct又不同于 MapStruct。主要原因是 ModelMapper 是利用反射的原理实现的 Object To Object。

ModelMapper 官方API ： [http://modelmapper.org/user-manual/property-mapping/][http_modelmapper.org_user-manual_property-mapping]

#### 使用实例 ####

本实例实现了条件映射、嵌套映射（对象中有对象映射）、自定义属性映射、List 集合映射（对象中有集合映射）、Map集合映射（对象中有集合映射）、忽略映射，默认值设置（ModelMapper 的默认值设置时一不小心就会入坑，如果直接设置默认值，当再赋值转换时，默认值会覆盖赋值的值，所以设置默认值需要结合条件映射）等。  
  验证了对象属性为集合，集合中还有集合能够使用 ModelMapper 进行转换。不足点是这个实例中没有验证有继承关系时的映射（使用 `modelMapper.includeBase(父类1, 父类2)` 方法），多个属性映射为一个属性或一个属性映射为多个属性（使用 `PropertyMap` 转换器）。

1.  使用条件映射设置默认值。当 age/createTime 没有值时设置默认值为18/当前时间，有值时不设置默认值；
2.  嵌套映射，自定义属性映射。Source 的 sourceSon 成员变量 映射到 Destination 的 destinationSon 成员变量；
3.  List集合映射。Source 的 listSon 成员变量 映射到 Destination 的 sonList 成员变量；
4.  Map集合映射。Source 的 mapSon 成员变量 映射到 Destination 的 sonMap 成员变量；
5.  忽略映射。忽略 Destination 的 excessParam 成员变量，如果不忽略将验证不过，报 org.modelmapper.MappingException: ModelMapper mapping errors；

1. 实体类

（1）BaseClass

@Getter
    @Setter
    public class BaseClass {
    
        private String id;
        private String name;
    
        public BaseClass() {
    
        }
    
        public BaseClass(String id, String name) {
            this.id = id;
            this.name = name;
        }
    }

（2）SouSubClass

@Getter
    @Setter
    public class SouSubClass {
    
        private String sonId;
        private String sonName;
        private List<BaseClass> grandSons;
    
        public SouSubClass() {
    
        }
    
        public SouSubClass(String sonId, String sonName) {
            this.sonId = sonId;
            this.sonName = sonName;
        }
    }

（3）DestSubClass

@Getter
    @Setter
    public class DestSubClass {
    
        private String dsonId;
        private String sonName;
        private String excessParam;
        private List<BaseClass> grandSons;
    
        public DestSubClass(){
    
        }
    
        public DestSubClass(String dsonId, String sonName) {
            this.dsonId = dsonId;
            this.sonName = sonName;
        }
    }

（4）Source

@Getter
    @Setter
    public class Source {
        private String id;
        private String name;
        private Integer age;
        private SouSubClass sourceSon;
        private List<SouSubClass> listSon;
        private Map<Integer, SouSubClass> mapSon;
        private Date createTime;
    
        public Source() {
    
        }
    
        public Source(String id, String name) {
            this.id = id;
            this.name = name;
        }
    
        public Source(String id, String name, Integer age) {
            this.id = id;
            this.name = name;
            this.age = age;
        }
    }

（5）Destination

@Getter
    @Setter
    public class Destination {
        private Long id;
        private String name;
        private Integer age;
        private DestSubClass destinationSon;
        private List<DestSubClass> sonList;
        private Map<Integer, DestSubClass> sonMap;
        private String excessParam;
        private Date createTime;
    
        public Destination() {
    
        }
    
        public Destination(Long id, String name) {
            this.id = id;
            this.name = name;
        }
    }

1.  ModelMapper 配置类

/**
     * 描述：ModelMapper 配置
     */
    @Configuration
    public class ModelMapperConfig {
    
        @Bean
        @Scope("singleton")
        public ModelMapper getModelMapper() {
            ModelMapper modelMapper = new ModelMapper();
            //默认为standard模式，设置为strict模式
            modelMapper.getConfiguration().setMatchingStrategy(MatchingStrategies.STRICT);
    
            // 类型映射代码
            sourceSonToDestinationSon(modelMapper);
            sourceToDestination(modelMapper);
    
            //验证映射
            modelMapper.validate();
    
            // 配置代码
            return modelMapper;
        }
    
        /**
         * 描述：声明 Source 类转 Destination 类的 Mapper
         * @param modelMapper
         * @Date  2019/05/09
         */
        private void sourceSonToDestinationSon(ModelMapper modelMapper) {
            modelMapper.createTypeMap(SouSubClass.class, DestSubClass.class)
                    .addMapping(SouSubClass::getSonId, DestSubClass::setDsonId)
                    .addMapping(SouSubClass::getSonName, DestSubClass::setSonName)
                    .addMappings(mapper -> mapper.skip(DestSubClass::setExcessParam));
        }
    
        private void sourceToDestination(ModelMapper modelMapper) {
            modelMapper.createTypeMap(Source.class, Destination.class)
                    .addMappings(mapper -> mapper.using((Converter<Integer, Integer>) context -> {
                            if (context.getSource() == null) {
                                return 18;
                            }
                            return context.getSource();
                        }).map(Source::getAge, Destination::setAge))
                    .addMappings(mapper -> mapper.using((Converter<Date, Date>) context -> {
                            if (context.getSource() == null) {
                                return new Date();
                            }
                            return context.getSource();
                        }).map(Source::getCreateTime, Destination::setCreateTime))
                    .addMapping(Source::getSourceSon, Destination::setDestinationSon)
                    .addMapping(Source::getListSon, Destination::setSonList)
                    .addMapping(Source::getMapSon, Destination::setSonMap)
                    .addMappings(mapper -> mapper.skip(Destination::setExcessParam));
        }
    }

1.  ModelMapper Service 类

public interface TestService {
    
        Destination testSourceToDestination(Source source);
    
        List<Destination> testSourceToDestinationList(List<Source> sources);
    }

@Service
    public class TestServiceImpl implements TestService {
    
        @Autowired
        private ModelMapper modelMapper;
    
        @Override
        public Destination testSourceToDestination(Source source) {
            Destination destination = modelMapper.map(source, Destination.class);
    
            return destination;  // a 处
        }
    
        @Override
        public List<Destination> testSourceToDestinationList(List<Source> sources) {
            Type type = new TypeToken<List<Destination>>(){}.getType();
            List<Destination> destinations = modelMapper.map(sources, type);
    
            return destinations; // b 处
        }
    }

1.  测试类

@RunWith(SpringRunner.class)
    @SpringBootTest(classes = TestApplication.class)
    public class TestServiceImplTest {
    
        @Autowired
        private TestService testService;
    
        private static Source source1 = new Source("a", "发生的", 24);
        private static Source source2 = new Source("b", "发生的");
    
        private static List<Source> sources = new ArrayList<>();
    
        static {
            List<BaseClass> baseClasses1 = new ArrayList<>();
            baseClasses1.add(new BaseClass("aa", "发生的111"));
            baseClasses1.add(new BaseClass("bb", "发生的222"));
            SouSubClass subClass1 = new SouSubClass("aaa", "发生的3333");
            subClass1.setGrandSons(baseClasses1);
    
            List<BaseClass> baseClasses2 = new ArrayList<>();
            baseClasses2.add(new BaseClass("cc", "国防观"));
            baseClasses2.add(new BaseClass("dd", "国防观"));
            SouSubClass subClass2 = new SouSubClass("ccc", "规范的大哥");
            subClass2.setGrandSons(baseClasses2);
    
            List<SouSubClass> sourceSonList = new ArrayList<>();
            sourceSonList.add(subClass1);
            sourceSonList.add(subClass2);
    
            Map<Integer, SouSubClass> sourceSonMap = new HashMap<>();
            sourceSonMap.put(1, subClass1);
            sourceSonMap.put(2, subClass2);
    
            source1.setCreateTime(new Date(System.currentTimeMillis()-98978609));
            source1.setSourceSon(subClass1);
            source1.setListSon(sourceSonList);
            source1.setMapSon(sourceSonMap);
    
            source2.setSourceSon(subClass1);
            source2.setListSon(sourceSonList);
            source2.setMapSon(sourceSonMap);
    
            sources.add(source1);
            sources.add(source2);
        }
    
        @Test
        public void testSourceToDestination() {
            testService.testSourceToDestination(source1);
            testService.testSourceToDestination(source2);
        }
    
        @Test
        public void testSourceToDestinationList() {
            testService.testSourceToDestinationList(sources);
        }
    }

1.  测试结果  
      在 ab 两处打上断点，查看变量转换前后的值，证实转换成功。

[http_modelmapper.org_user-manual_property-mapping]: http://modelmapper.org/user-manual/property-mapping/