对象必须在其@XmlValue字段中具有一些值

Question

我有以下代码

@XmlAccessorType(XmlAccessType.FIELD)
@XmlType(name = "udt_TextType", propOrder = { "value" })
@XmlSeeAlso({ RoadTypeCodeTypeType.class })
public class UdtTextType {

@XmlValue
@XmlJavaTypeAdapter(NormalizedStringAdapter.class)
@XmlSchemaType(name = "normalizedString")
protected String value;

/**
 * Gets the value of the value property.
 * 
 * @return possible object is {@link String }
 * 
 */
public String getValue() {
    return value;
}

/**
 * Sets the value of the value property.
 * 
 * @param value
 *            allowed object is {@link String }
 * 
 */
public void setValue(String value) {
    this.value = value;
}

当我试图编组这个对象时:

@XmlAccessorType(XmlAccessType.FIELD)
@XmlType(name = "AdresseCompleteType", propOrder = { "inHouseMail", "buildingName", "buildingNumber", "blockName", "roadType",
        "streetName", "postcode", "cityName", "lineFive" })
public class AdresseCompleteType {

    @XmlElement(name = "InHouseMail")
    protected UdtTextType inHouseMail;
    @XmlElement(name = "BuildingName")
    protected UdtTextType buildingName;
    @XmlElement(name = "BuildingNumber")
    protected UdtTextType buildingNumber;
    ...

我有以下错误:对象必须在其@XmlValue字段中具有一些值

为什么我会收到此错误？

com.sun.xml.internal.bind.api.AccessorException: Object must have some value in its @XmlValue field: fr.company.jaxb.UdtTextType@17f2dd8] at 
    fr.company.Service.launchXML(Service.java:303) at 
    fr.company.Service.launchZIP(Service.java:370) at 
    fr.company.MainTest.testGenerationZip(MainTest.java:17) at 
    sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at 
    sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57))

谢谢!

Answer 1

以下解释了您收到异常的原因：

Java模型

以下是演示该问题的模型的简化版本：

Udt文本类型

该类有一个注释为的字段@XmlValue：

import javax.xml.bind.annotation.*;

@XmlAccessorType(XmlAccessType.FIELD)
public class UdtTextType {

    @XmlValue
    protected String value;

    public void setValue(String value) {
        this.value = value;
    }

}

地址完整类型

需要注意的重要一点是，inHouseMail字段是一种与@XmlValue.

import javax.xml.bind.annotation.*;

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

    @XmlElement(name = "InHouseMail")
    protected UdtTextType inHouseMail;

    public void setInHouseMail(UdtTextType inHouseMail) {
        this.inHouseMail = inHouseMail;
    }

}

XML表示

让我们检查一下对象模型中可能出现的不同 XML 表示形式。

#1 -inHouseMail属性是null

AdreseCompleteType adreseCompleteType = new AdreseCompleteType();
adreseCompleteType.setInHouseMail(null);

在 XML 表示中，该inHouseMail字段应该null是在生成的 XML 中不包含该元素。

import javax.xml.bind.annotation.*;

@XmlAccessorType(XmlAccessType.FIELD)
public class UdtTextType {

    @XmlValue
    protected String value;

    public void setValue(String value) {
        this.value = value;
    }

}

#2 -inHouseMail属性已设置并UdtTextType具有值

UdtTextType udtTextType = new UdtTextType();
udtTextType.setValue("Hello World");

AdreseCompleteType adreseCompleteType = new AdreseCompleteType();
adreseCompleteType.setInHouseMail(udtTextType);

由于inHouseMail设置了字段，我们得到了InHouseMail元素，并且由于其value字段已填充，因此也会输出。

import javax.xml.bind.annotation.*;

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

    @XmlElement(name = "InHouseMail")
    protected UdtTextType inHouseMail;

    public void setInHouseMail(UdtTextType inHouseMail) {
        this.inHouseMail = inHouseMail;
    }

}

#3 -inHouseMail属性已设置并且UdtTextType具有空字符串值

UdtTextType udtTextType = new UdtTextType();
udtTextType.setValue("");

AdreseCompleteType adreseCompleteType = new AdreseCompleteType();
adreseCompleteType.setInHouseMail(udtTextType);

由于inHouseMail设置了字段，我们得到了InHouseMail元素，并且由于其value字段填充为空String，因此输出为空元素。

AdreseCompleteType adreseCompleteType = new AdreseCompleteType();
adreseCompleteType.setInHouseMail(null);

#4 -inHouseMail属性已设置并UdtTextType具有null值

UdtTextType udtTextType = new UdtTextType();
udtTextType.setValue(null);

AdreseCompleteType adreseCompleteType = new AdreseCompleteType();
adreseCompleteType.setInHouseMail(udtTextType);

问题是这个 XML 应该是什么样子。它不能是像 #3 这样的空元素，因为 JAXB（和 XML）不将 null 表示为空元素。它也不能表示为缺失InHouseMail元素，因为这会与场景 #1 发生冲突。所以会抛出以下异常：

Exception in thread "main" javax.xml.bind.MarshalException
 - with linked exception:
[com.sun.istack.internal.SAXException2: Object must have some value in its @XmlValue field: forum28411016.UdtTextType@f7ca0f5
com.sun.xml.internal.bind.api.AccessorException: Object must have some value in its @XmlValue field: forum28411016.UdtTextType@f7ca0f5]
    at com.sun.xml.internal.bind.v2.runtime.MarshallerImpl.write(MarshallerImpl.java:311)
    at com.sun.xml.internal.bind.v2.runtime.MarshallerImpl.marshal(MarshallerImpl.java:236)
    at javax.xml.bind.helpers.AbstractMarshallerImpl.marshal(AbstractMarshallerImpl.java:95)
    at forum28411016.Demo.main(Demo.java:18)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:606)
    at com.intellij.rt.execution.application.AppMain.main(AppMain.java:134)
Caused by: com.sun.istack.internal.SAXException2: Object must have some value in its @XmlValue field: forum28411016.UdtTextType@f7ca0f5
com.sun.xml.internal.bind.api.AccessorException: Object must have some value in its @XmlValue field: forum28411016.UdtTextType@f7ca0f5
    at com.sun.xml.internal.bind.v2.runtime.XMLSerializer.reportError(XMLSerializer.java:235)
    at com.sun.xml.internal.bind.v2.runtime.XMLSerializer.reportError(XMLSerializer.java:250)
    at com.sun.xml.internal.bind.v2.runtime.ClassBeanInfoImpl.serializeBody(ClassBeanInfoImpl.java:347)
    at com.sun.xml.internal.bind.v2.runtime.XMLSerializer.childAsSoleContent(XMLSerializer.java:582)
    at com.sun.xml.internal.bind.v2.runtime.ClassBeanInfoImpl.serializeRoot(ClassBeanInfoImpl.java:325)
    at com.sun.xml.internal.bind.v2.runtime.XMLSerializer.childAsRoot(XMLSerializer.java:483)
    at com.sun.xml.internal.bind.v2.runtime.MarshallerImpl.write(MarshallerImpl.java:308)
    ... 8 more
Caused by: com.sun.xml.internal.bind.api.AccessorException: Object must have some value in its @XmlValue field: forum28411016.UdtTextType@f7ca0f5
    at com.sun.xml.internal.bind.v2.model.impl.RuntimeClassInfoImpl$TransducerImpl.writeLeafElement(RuntimeClassInfoImpl.java:395)
    at com.sun.xml.internal.bind.v2.runtime.reflect.TransducedAccessor$CompositeTransducedAccessorImpl.writeLeafElement(TransducedAccessor.java:239)
    at com.sun.xml.internal.bind.v2.runtime.property.SingleElementLeafProperty.serializeBody(SingleElementLeafProperty.java:114)
    at com.sun.xml.internal.bind.v2.runtime.ClassBeanInfoImpl.serializeBody(ClassBeanInfoImpl.java:343)
    ... 12 more