MapStruct 使用 constant

MapStruct 允许将常量值映射到属性。

语法

@Mapping(target = "target-property", const = "const-value")

• target-property - 我们正在为其进行映射的属性。
• const-value - 映射器将 const-value 映射到 target-property。

示例

打开使用 dateFormat 映射章节中更新的项目映射。

使用以下代码更新 CarEntity.java

CarEntity.java

package com.jiyik.entity;

import java.util.GregorianCalendar;

public class CarEntity {
    private int id;
    private double price;
    private GregorianCalendar manufacturingDate;
    public int getId() {
        return id;
    }
    public void setId(int id) {
        this.id = id;
    }
    public double getPrice() {
        return price;
    }
    public void setPrice(double price) {
        this.price = price;
    }
    public GregorianCalendar getManufacturingDate() {
        return manufacturingDate;
    }
    public void setManufacturingDate(GregorianCalendar manufacturingDate) {
        this.manufacturingDate = manufacturingDate;
    }
}

使用以下代码更新 Car.java

Car.java

package com.jiyik.model;

public class Car {
    private int id;
    private String price;
    private String manufacturingDate;
    private String brand;
    public int getId() {
        return id;
    }
    public void setId(int id) {
        this.id = id;
    }
    public String getPrice() {
        return price;
    }
    public void setPrice(String price) {
        this.price = price;
    }
    public String getManufacturingDate() {
        return manufacturingDate;
    }
    public void setManufacturingDate(String manufacturingDate) {
        this.manufacturingDate = manufacturingDate;
    }
    public String getBrand() {
        return brand;
    }
    public void setBrand(String brand) {
        this.brand = brand;
    }
}

使用以下代码更新 CarMapper.java

CarMapper.java

package com.jiyik.mapper;

import com.jiyik.entity.CarEntity;
import com.jiyik.model.Car;
import org.mapstruct.Mapper;
import org.mapstruct.Mapping;

@Mapper
public interface CarMapper {
    @Mapping(target = "brand", constant = "BMW")
    @Mapping(source = "price", target = "price", numberFormat = "$#.00")
    @Mapping(source = "manufacturingDate", target = "manufacturingDate", dateFormat = "dd.MM.yyyy")
    Car getModelFromEntity(CarEntity carEntity);
}

使用以下代码更新 CarMapperTest.java

CarMapperTest.java

import com.jiyik.entity.CarEntity;
import com.jiyik.mapper.CarMapper;
import com.jiyik.model.Car;
import org.junit.Test;
import org.mapstruct.factory.Mappers;

import java.util.GregorianCalendar;

import static org.junit.Assert.assertEquals;

public class CarMapperTest { private CarMapper carMapper = Mappers.getMapper(CarMapper.class);

@Test
public void testEntityToModel() {
    CarEntity entity = new CarEntity();
    entity.setPrice(345000);
    entity.setId(1);
    entity.setManufacturingDate(new GregorianCalendar(2015, 3, 5));
    Car model = carMapper.getModelFromEntity(entity);
    assertEquals(model.getPrice(), "$345000.00");
    assertEquals(entity.getId(), model.getId());
    assertEquals("05.04.2015", model.getManufacturingDate());
    assertEquals("BMW", model.getBrand());
}

}

运行以下命令来测试映射。

$ mvn clean test

执行结果如下