java - JAXBElement 与 boolean 值

Question

JAXBElement Boolean 到底是什么？我如何将其设置为与“true”等效的 boolean 值？

方法:

  public void setIncludeAllSubaccounts(JAXBElement<Boolean> paramJAXBElement)
  {
    this.includeAllSubaccounts = paramJAXBElement;
  }

这不编译:

returnMessageFilter.setIncludeAllSubaccounts(true); 

Answer 1

JAXBElement 是在 JAXB (JSR-222) 实现无法单独根据值判断要做什么时作为模型的一部分生成的。在您的示例中，您可能有一个类似的元素:

<xsd:element 
    name="includeAllSubaccounts" type="xsd:boolean" nillable="true" minOccurs="0"/>

生成的属性不能是boolean，因为boolean 不代表null。您可以将属性设置为 Boolean，但是您如何区分丢失的元素和使用 xsi:nil 设置的元素。这就是 JAXBElement 的用武之地。请参阅下面的完整示例:

福

package forum12713373;

import javax.xml.bind.JAXBElement;
import javax.xml.bind.annotation.*;

@XmlRootElement
@XmlAccessorType(XmlAccessType.FIELD)
public class Foo {

    @XmlElementRef(name="absent")
    JAXBElement<Boolean> absent;

    @XmlElementRef(name="setToNull")
    JAXBElement<Boolean> setToNull;

    @XmlElementRef(name="setToValue")
    JAXBElement<Boolean> setToValue;

}

对象工厂

package forum12713373;

import javax.xml.bind.JAXBElement;
import javax.xml.bind.annotation.*;
import javax.xml.namespace.QName;

@XmlRegistry
public class ObjectFactory {

    @XmlElementDecl(name="absent")
    public JAXBElement<Boolean> createAbsent(Boolean value) {
        return new JAXBElement(new QName("absent"), Boolean.class, value);
    }

    @XmlElementDecl(name="setToNull")
    public JAXBElement<Boolean> createSetToNull(Boolean value) {
        return new JAXBElement(new QName("setToNull"), Boolean.class, value);
    }

    @XmlElementDecl(name="setToValue")
    public JAXBElement<Boolean> createSetToValue(Boolean value) {
        return new JAXBElement(new QName("setToValue"), Boolean.class, value);
    }

}

演示

package forum12713373;

import javax.xml.bind.*;

public class Demo {

    public static void main(String[] args) throws Exception {
        JAXBContext jc = JAXBContext.newInstance(Foo.class);

        ObjectFactory objectFactory = new ObjectFactory();

        Foo foo = new Foo();
        foo.absent = null;
        foo.setToNull = objectFactory.createSetToNull(null);
        foo.setToValue = objectFactory.createSetToValue(false);

        Marshaller marshaller = jc.createMarshaller();
        marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);
        marshaller.marshal(foo, System.out);
    }

}

输出

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<foo>
    <setToNull xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:nil="true"/>
    <setToValue>false</setToValue>
</foo>