使用 Dozer 将原始类（字符串、布尔值等）相互映射

Question

我正在尝试使用 Dozer 自动从原始类相互映射。最后，代码可能会变成这样。

Boolean resultBoolean = mapper.map("true", Boolean.class);

虽然 Dozer 在 bean 中确实支持将 String 映射到 Boolean，但似乎直接映射到 Boolean 会产生以下异常。

org.dozer.MappingException: java.lang.NoSuchMethodException: java.lang.Boolean.<init>()
at org.dozer.util.MappingUtils.throwMappingException(MappingUtils.java:88)
at org.dozer.factory.ConstructionStrategies$ByConstructor.newInstance(ConstructionStrategies.java:261)
at org.dozer.factory.ConstructionStrategies$ByConstructor.create(ConstructionStrategies.java:245)
at org.dozer.factory.DestBeanCreator.create(DestBeanCreator.java:65)
at org.dozer.MappingProcessor.map(MappingProcessor.java:178)
at org.dozer.MappingProcessor.map(MappingProcessor.java:125)
at org.dozer.MappingProcessor.map(MappingProcessor.java:120)
at org.dozer.DozerBeanMapper.map(DozerBeanMapper.java:111)

...

Caused by: java.lang.NoSuchMethodException: java.lang.Boolean.<init>()
at java.lang.Class.getConstructor0(Class.java:2706)
at java.lang.Class.getDeclaredConstructor(Class.java:1985)
at org.dozer.factory.ConstructionStrategies$ByConstructor.newInstance(ConstructionStrategies.java:257)
... 32 more

很明显，Dozer 正在尝试实例化布尔值本身。我可以创建一个客户DozerConverter 将布尔值转换为字符串，但我不想重新实现 Dozer 已有的代码。有没有办法让 Dozer 直接映射到原始类型？

Answer 1

您可以使用 org.dozer.converters.PrimitiveOrWrapperConverter 代替 org.dozer.DozerBeanMapper ：

import org.dozer.converters.DateFormatContainer;
import org.dozer.converters.PrimitiveOrWrapperConverter;

public class DozerPrimitiveMapping {


    public static void main(String[] args) {

        PrimitiveOrWrapperConverter primitiveConverter = new PrimitiveOrWrapperConverter();
        //DateFormatContainer is not needed in this String-to-Boolean use case, but the converter would throw an error if it was null
        DateFormatContainer dateFormatContainer = new DateFormatContainer("");
        Boolean booleanResult= (Boolean) primitiveConverter.convert("true", Boolean.class, dateFormatContainer);
        System.out.println("Boolean result from dozer: "+booleanResult);
    }
}

或者将其全部封装在自定义转换器中：

package my.dozer.test;

import org.dozer.CustomConverter;
import org.dozer.converters.DateFormatContainer;
import org.dozer.converters.PrimitiveOrWrapperConverter;

public class DozerPrimitiveConverter implements CustomConverter {

    private final PrimitiveOrWrapperConverter primitiveConverter = new PrimitiveOrWrapperConverter();
    //DateFormatContainer is not needed in this String-to-Boolean use case, but the converter would throw an error if it was null
    private final DateFormatContainer dateFormatContainer = new DateFormatContainer("");

    @Override
    public Object convert(Object existingDestinationFieldValue, Object sourceFieldValue, Class<?> destinationClass, Class<?> sourceClass) {
        Boolean booleanResult = (Boolean) primitiveConverter.convert(sourceFieldValue, Boolean.class, dateFormatContainer);
        return booleanResult;
    }

}

并像在此示例配置文件dozer-primitive-mapping.xml 中一样配置转换器：

<?xml version="1.0" encoding="UTF-8"?>
<mappings xmlns="http://dozer.sourceforge.net"
          xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
          xsi:schemaLocation="http://dozer.sourceforge.net
          http://dozer.sourceforge.net/schema/beanmapping.xsd">

    <configuration>
        <custom-converters>
          <converter type="my.dozer.test.DozerPrimitiveConverter" >
              <class-a>java.lang.String</class-a>
              <class-b>java.lang.Boolean</class-b>
          </converter>
        </custom-converters>
    </configuration>

</mappings>

使用自定义转换器运行映射的示例类：

package my.dozer.test;

import java.io.InputStream;
import org.dozer.DozerBeanMapper;

public class DozerPrimitiveConverterApp {

    public static void main(String[] args) {
        DozerBeanMapper mapper = new DozerBeanMapper();
        InputStream is = DozerPrimitiveConverterApp.class.getClassLoader().getResourceAsStream("dozer-primitive-mapping.xml");
        mapper.addMapping(is);

        Boolean booleanValue = mapper.map("false", Boolean.class);
        System.out.println("Boolean result from dozer with custom converter: " + booleanValue);

    }
}