在開發(fā)過程中經(jīng)常會有一個需求，就是類型轉(zhuǎn)換 (把一個類轉(zhuǎn)成另一個類)modelmapper就是一個提高生產(chǎn)力的工具

• 入門
• 內(nèi)置匹配器
• 自定義匹配器
• 源碼映射解析

入門

1. 方式1 (默認(rèn)配置)

• 導(dǎo)入maven依賴

<!-- http://modelmapper.org/getting-started/-->
<dependency>
     <groupId>org.modelmapper</groupId>
     <artifactId>modelmapper</artifactId>
     <version>2.3.0</version>
</dependency>

• 新建三個實體

public class AppleVo {
    private String name ;
    private String id ;
    
}
public class Apple {
    private String id ;
    private String name ;
    private String createAge ;
}
public class AppleDTO {
    private String name ;
    private String create_age ;
}

• 測試

    public static Apple apple;
    public static List<Apple> apples;
    
    /**
     * 模擬數(shù)據(jù)
     */
    static {
        apple = new Apple();
        apple.setName("black");
        apple.setCreateAge("22");
        apple.setId("1");
        apples = new ArrayList<>(16);
        Apple apple1 = new Apple("1", "red", "21");
        Apple apple2 = new Apple("2", "blue", "22");
        Apple apple3 = new Apple("3", "yellow", "23");
        apples.add(apple1);
        apples.add(apple2);
        apples.add(apple3);
        
    }

    
    
    /**
     *
     *  屬性名保持一致，采用默認(rèn)規(guī)則
     */
    public  void test1() {
        ModelMapper modelMapper = new ModelMapper();
        AppleDTO appleDto = modelMapper.map(apple, AppleDTO.class);
        System.out.println(appleDto.toString());
    }

2. 使用內(nèi)置匹配策略

   官方提供了多種匹配策略，可以去官網(wǎng)詳細(xì)了解

   image.png

public  void test2() {
        ModelMapper modelMapper = new ModelMapper();
        modelMapper.getConfiguration()
                /**  LOOSE松散策略 */
                .setMatchingStrategy(MatchingStrategies.LOOSE);
        AppleDTO appleDto = modelMapper.map(apple, AppleDTO.class);
        System.out.println(appleDto.toString());
    }

3. 自定義映射規(guī)則

private  static  PropertyMap customField(){
    /**
     * 自定義映射規(guī)則
     */
     return  new PropertyMap<Apple, AppleDTO>() {
     @Override
            protected void configure() {
            /**使用自定義轉(zhuǎn)換規(guī)則*/
            map(source.getCreateAge(),destination.getCreate_age());
        }
   };
}

 public void test4(){
        ModelMapper modelMapper = new ModelMapper();
        modelMapper.addMappings(customField()) ;
        List<AppleDTO> userDTOS = modelMapper.map(apples,new TypeToken<List<AppleDTO>>() {}.getType());
        System.out.println(userDTOS);
    }

4. 源碼映射解析

在mappermodel中，一般情況下保持屬性名一致即可以不用任何配置就可直接轉(zhuǎn)換，mappermodel的原理是基于反射原理進(jìn)行賦值的,或是直接對成員變量賦值的，走一波debug,如圖

//入口方法
public <S, D> D map(S source, Class<S> sourceType, D destination,
      TypeToken<D> destinationTypeToken, String typeMapName) {}

  //類型映射
  <S, D> D typeMap(MappingContextImpl<S, D> context, TypeMap<S, D> typeMap) {
  }

image.png

//屬性賦值
private <S, D> void setDestinationValue(MappingContextImpl<S, D> context,
      MappingContextImpl<Object, Object> propertyContext, MappingImpl mapping) {}

image.png