ModelMapper 的高级使用

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/

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 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 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 listSon;
    private Map 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 sonList;
    private Map sonMap;
    private String excessParam;
    private Date createTime;

    public Destination() {

    }

    public Destination(Long id, String name) {
        this.id = id;
        this.name = name;
    }
}

2. 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) context -> {
                        if (context.getSource() == null) {
                            return 18;
                        }
                        return context.getSource();
                    }).map(Source::getAge, Destination::setAge))
                .addMappings(mapper -> mapper.using((Converter) 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));
    }
}

3. ModelMapper Service 类

public interface TestService {

    Destination testSourceToDestination(Source source);

    List testSourceToDestinationList(List 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 testSourceToDestinationList(List sources) {
        Type type = new TypeToken>(){}.getType();
        List destinations = modelMapper.map(sources, type);

        return destinations; // b 处
    }
}

4. 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 sources = new ArrayList<>();

    static {
        List 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 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 sourceSonList = new ArrayList<>();
        sourceSonList.add(subClass1);
        sourceSonList.add(subClass2);

        Map 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);
    }
}

5. 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。