mapstruct的用法-numberFormat

这里要注意，是String转Number或Number或String才有效，如果是Number转Number或其他类型的转换均不生效，比如Double转Double（用于格式化小数位）时不生效。

先浏览：mapstruct的用法-qualifiedByName，用的都是这里的类。

1 在Mapper中定义方法如下：Number转Number

    @Mapping(source = "pm25", target = "pm25", numberFormat = "0.00")//不生效
    AreaVO areaPO2areaVO(AreaPO areaPO);

2 运行后，Impl类如下：

package com.weather.weatherexpert.common.model.mapper;

import com.weather.weatherexpert.common.model.po.AreaPO;
import com.weather.weatherexpert.common.model.vo.AreaVO;

public class ConvertMapperImpl implements ConvertMapper {
    public ConvertMapperImpl() {
    }

    public AreaVO areaPO2areaVO(AreaPO areaPO) {
        if (areaPO == null) {
            return null;
        } else {
            AreaVO areaVO = new AreaVO();
            areaVO.setPm25(areaPO.getPm25());
            areaVO.setCityName(areaPO.getCityName());
            areaVO.setHaveAir(areaPO.getHaveAir());
            return areaVO;
        }
    }
}

并没有小数位格式的代码

输出：

JSON.toJSONString(areaVO):{"cityName":"忻州","haveAir":1,"pm25":1.256879}

3 Mapper修改如下：Number转String

    @Mapping(source = "pm25", target = "pm25Str", numberFormat = "0.00")//生效，Number转String或String转Number才可以，如果是Number转Number则无效
    AreaVO areaPO2areaVO(AreaPO areaPO);//Number转String

4 运行后，Impl类如下：

package com.weather.weatherexpert.common.model.mapper;

import com.weather.weatherexpert.common.model.po.AreaPO;
import com.weather.weatherexpert.common.model.vo.AreaVO;
import java.text.DecimalFormat;

public class ConvertMapperImpl implements ConvertMapper {
    public ConvertMapperImpl() {
    }

    public AreaVO areaPO2areaVO(AreaPO areaPO) {
        if (areaPO == null) {
            return null;
        } else {
            AreaVO areaVO = new AreaVO();
            if (areaPO.getPm25() != null) {
                areaVO.setPm25Str((new DecimalFormat("0.00")).format(areaPO.getPm25()));
            }

            areaVO.setCityName(areaPO.getCityName());
            areaVO.setHaveAir(areaPO.getHaveAir());
            areaVO.setPm25(areaPO.getPm25());
            return areaVO;
        }
    }
}

有小数位格式的代码，这里是Number转String

输出：

{"cityName":"忻州","haveAir":1,"pm25":1.256879,"pm25Str":"1.26"}

5 Mapper修改如下：String转Number

    @Mapping(source = "pm10Str", target = "pm10", numberFormat = "0.00")//String转Number
    AreaVO areaPO2areaVO(AreaPO areaPO);

6 测试：

7 运行后，Impl类如下：

package com.weather.weatherexpert.common.model.mapper;

import com.weather.weatherexpert.common.model.po.AreaPO;
import com.weather.weatherexpert.common.model.vo.AreaVO;
import java.text.DecimalFormat;
import java.text.ParseException;

public class ConvertMapperImpl implements ConvertMapper {
    public ConvertMapperImpl() {
    }

    public AreaVO areaPO2areaVO(AreaPO areaPO) {
        if (areaPO == null) {
            return null;
        } else {
            AreaVO areaVO = new AreaVO();

            try {
                if (areaPO.getPm10Str() != null) {
                    areaVO.setPm10((new DecimalFormat("0.00")).parse(areaPO.getPm10Str()).doubleValue());
                }
            } catch (ParseException var4) {
                throw new RuntimeException(var4);
            }

            areaVO.setCityName(areaPO.getCityName());
            areaVO.setHaveAir(areaPO.getHaveAir());
            areaVO.setPm25(areaPO.getPm25());
            return areaVO;
        }
    }
}

输出：

JSON.toJSONString(areaVO2):{"cityName":"忻州","haveAir":1,"pm10":12.12315464,"pm25":1.256879}

发现pm10属性的小数位并没有按照预期格式化！

    public static void main(String[] args) {
        try {
            Double d1 = new DecimalFormat("0.00").parse("12.1321312").doubleValue();
            System.out.println("d1:" + d1);//12.1321312

            Double d2 = new Double(new DecimalFormat("0.00").format(Double.parseDouble("12.1321312")));
            System.out.println("d2:" + d2);//12.13
        } catch (ParseException e) {
            e.printStackTrace();
        }
    }

这String转Number时小数位并没有按预期转换，不知是哪里写错了，还是哪里写的不正确！

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