在开发过程中经常会有一个需求，就是类型转换 (把一个类转成另一个类)modelmapper就是一个提高生产力的工具

• 入门
• 内置匹配器
• 自定义匹配器
• 源码映射解析

入门

1. 方式1 (默认配置)

• 导入maven依赖

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

• 新建三个实体

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 ;
}

• 测试

    public static Apple apple;
    public static List<Apple> apples;
    
    /**
     * 模拟数据
     */
    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);
        
    }

    /**
     *
     *  属性名保持一致，采用默认规则
     */
    public  void test1() {
        ModelMapper modelMapper = new ModelMapper();
        AppleDTO appleDto = modelMapper.map(apple, AppleDTO.class);
        System.out.println(appleDto.toString());
    }

1. 使用内置匹配策略 官方提供了多种匹配策略，可以去官网详细了解

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());
    }

1. 自定义映射规则

private  static  PropertyMap customField(){
    /**
     * 自定义映射规则
     */
     return  new PropertyMap<Apple, AppleDTO>() {
     @Override
            protected void configure() {
            /**使用自定义转换规则*/
            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);
    }

1. 源码映射解析

在mappermodel中，一般情况下保持属性名一致即可以不用任何配置就可直接转换，mappermodel的原理是基于反射原理进行赋值的,或是直接对成员变量赋值的，走一波debug,如图

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

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

image.png

//属性赋值
private <S, D> void setDestinationValue(MappingContextImpl<S, D> context,
      MappingContextImpl<Object, Object> propertyContext, MappingImpl mapping) {}

image.png