java - JAXB 解码错误 : UnmarshalException- Unexpected Element - Expected elements are (none) - @XmlRootElement NOT missing

Question

我在解码某些 XML 时遇到问题。部分堆栈转储如下所示:

javax.xml.bind.UnmarshalException: unexpected element (uri:"", local:"properties"). Expected elements are (none)
    at com.sun.xml.internal.bind.v2.runtime.unmarshaller.UnmarshallingContext.handleEvent(UnmarshallingContext.java:726)
    at com.sun.xml.internal.bind.v2.runtime.unmarshaller.Loader.reportError(Loader.java:247)
    at com.sun.xml.internal.bind.v2.runtime.unmarshaller.Loader.reportError(Loader.java:242)

下面是我试图解码的 XML，XJC 生成的根元素 Java 类，XSD 馈送到 XJC，最后是 XJC 生成的 ObjectFactory。

我正在解码的 XML:

<?xml version="1.0" encoding="UTF-8"?>
<properties program-name="EstateAccounting"
                        properties-file="EstateAccounting.properties">
                        
    <keyword-properties>
        <keyword-property type="string" name="reportDirectory" alias="rd">
            <description>
                <![CDATA[Specifies the optional report directory.  Double quotes are required if the report directory
                contains spaces.  The report directory specifies where the intermediate XML used to produce the PDF report
                and where the PDF report should be produced.]]>
            </description>
        </keyword-property>
        
        <keyword-property type="string" name="beneficiary" alias="b">
            <description>
                <![CDATA[Specifies the optional beneficary name.  Double quotes are required if the beneficiary name
                contains spaces.  When omitted, all beneficiaries are included.]]>
            </description>
        </keyword-property>
        
        <keyword-property type="string" name="date" alias="d">
            <description>
                <![CDATA[Specifies the optional date(s).  The format is mm/yyyy.  Double quotes are required 
                when specifying a date range as "start-date - end-date" (spaces optional).  When omitted,
                all dates are included.]]>
            </description>
        </keyword-property>
        
        <keyword-property type="boolean" name="isGenerateReport" alias="r">
            <description>
                <![CDATA[Indicates that a PDF report should be produced.  One report for each generated XML file will be produced.]]>
            </description>
        </keyword-property>
        
        <keyword-property type="boolean" name="isKeepIntermediateXML" alias="xml">
            <description>
                <![CDATA[Indicates that the XML file used to produce the PDF report should be retained.  Normally, when the -r option
                indicates that a PDF report should be produced, the generated intermediate XML file is deleted.]]>
            </description>
        </keyword-property>
    </keyword-properties>
    
    <positional-properties>
        <positional-property type="string" name="spreadsheet" required="false">
            <description>
                <![CDATA[The location of the input spreadsheet.]]>
            </description>
        </positional-property>
        
        <positional-property type="string" name="intermediateXML" required="false">
            <description>
                <![CDATA[The location of a previously generated EstateAccounting intermediate XML file.  This is specified when 
                 a report based on previously generated intermediate XML is required.]]>
            </description>
        </positional-property>
    </positional-properties>
    
    <mutual-properties>
        <mutual-property-set type="exclusive">
            <mutual-property name="spreadsheet"/>
            <mutual-property name="intermediateXML"/>
        </mutual-property-set>
    </mutual-properties>
</properties>

部分 XJC 生成的根元素 Java 类。请注意 @XmlRootElement(name = "properties") 在 Properties 类中的包含:

//
// This file was generated by the Eclipse Implementation of JAXB, v3.0.2 
// See https://eclipse-ee4j.github.io/jaxb-ri 
// Any modifications to this file will be lost upon recompilation of the source schema. 
// Generated on: 2022.01.26 at 10:38:30 AM PST 
//

package com.mbm.properties.jaxb;

import java.util.ArrayList;
import java.util.List;
import jakarta.xml.bind.annotation.XmlAccessType;
import jakarta.xml.bind.annotation.XmlAccessorType;
import jakarta.xml.bind.annotation.XmlAttribute;
import jakarta.xml.bind.annotation.XmlElement;
import jakarta.xml.bind.annotation.XmlRootElement;
import jakarta.xml.bind.annotation.XmlTransient;
import jakarta.xml.bind.annotation.XmlType;
import org.glassfish.jaxb.core.Locatable;
import org.glassfish.jaxb.core.annotation.XmlLocation;
import org.xml.sax.Locator;


/**
 * <p>Java class for anonymous complex type.
 * 
 * <p>The following schema fragment specifies the expected content contained within this class.
 * 
 * <pre>
 * &lt;complexType&gt;
 *   &lt;complexContent&gt;
 *     &lt;restriction base="{http://www.w3.org/2001/XMLSchema}anyType"&gt;
 *       &lt;sequence&gt;
 *         &lt;element name="description" type="{urn:com-mbm-properties-jaxb}descriptionType" maxOccurs="unbounded" minOccurs="0"/&gt;
 *         &lt;element name="keyword-properties" type="{urn:com-mbm-properties-jaxb}keywordPropertiesType" minOccurs="0"/&gt;
 *         &lt;element name="positional-properties" type="{urn:com-mbm-properties-jaxb}positionalPropertiesType" minOccurs="0"/&gt;
 *         &lt;element name="mutual-properties" type="{urn:com-mbm-properties-jaxb}MutualPropertiesType" minOccurs="0"/&gt;
 *       &lt;/sequence&gt;
 *       &lt;attribute name="program-name" type="{http://www.w3.org/2001/XMLSchema}string" /&gt;
 *       &lt;attribute name="properties-file" type="{http://www.w3.org/2001/XMLSchema}string" /&gt;
 *       &lt;attribute name="debug" type="{http://www.w3.org/2001/XMLSchema}boolean" default="false" /&gt;
 *       &lt;attribute name="strict-property-retrieval" type="{http://www.w3.org/2001/XMLSchema}boolean" default="true" /&gt;
 *       &lt;attribute name="strict-command-line" type="{http://www.w3.org/2001/XMLSchema}boolean" default="true" /&gt;
 *       &lt;attribute name="usage" type="{http://www.w3.org/2001/XMLSchema}boolean" default="false" /&gt;
 *     &lt;/restriction&gt;
 *   &lt;/complexContent&gt;
 * &lt;/complexType&gt;
 * </pre>
 * 
 * 
 */
@XmlAccessorType(XmlAccessType.FIELD)
@XmlType(name = "", propOrder = {
    "descriptions",
    "containerOfListOfKeywordProperties",
    "containerOfListOfPositionalProperties",
    "mutualProperties"
})
@XmlRootElement(name = "properties")
public class Properties
    implements Locatable
{

    @XmlElement(name = "description")
    protected List<DescriptionType> descriptions;
    @XmlElement(name = "keyword-properties")
    protected KeywordPropertiesType containerOfListOfKeywordProperties;
    @XmlElement(name = "positional-properties")
    protected PositionalPropertiesType containerOfListOfPositionalProperties;
    @XmlElement(name = "mutual-properties")
    protected MutualPropertiesType mutualProperties;
    @XmlAttribute(name = "program-name")
    protected String programName;
    @XmlAttribute(name = "properties-file")
    protected String propertiesFile;
    @XmlAttribute(name = "debug")
    protected Boolean debug;
    @XmlAttribute(name = "strict-property-retrieval")
    protected Boolean strictPropertyRetrieval;
    @XmlAttribute(name = "strict-command-line")
    protected Boolean strictCommandLine;
    @XmlAttribute(name = "usage")
    protected Boolean usage;
    @XmlLocation
    @XmlTransient
    protected Locator locator;

    .
    .
    .

    public Locator sourceLocation() {
        return locator;
    }

    public void setSourceLocation(Locator newLocator) {
        locator = newLocator;
    }
}

XSD 被送入生成 Java 类的 XJC:

<?xml version="1.0" encoding="UTF-8"?>
<xsd:schema xmlns:xjc="http://java.sun.com/xml/ns/jaxb/xjc"
            xmlns:jaxb="https://jakarta.ee/xml/ns/jaxb"
            xmlns:xsd="http://www.w3.org/2001/XMLSchema"
            xmlns="urn:com-mbm-properties-jaxb"
            targetNamespace="urn:com-mbm-properties-jaxb"
            elementFormDefault="qualified"
            jaxb:extensionBindingPrefixes="xjc"
            jaxb:version="3.0">

    <xsd:annotation>
        <xsd:appinfo>
            <jaxb:globalBindings>
                <xjc:simple/>
            </jaxb:globalBindings>
        </xsd:appinfo>
    </xsd:annotation>
    
    <xsd:element name="properties">
        <xsd:complexType>
            <xsd:sequence>
                <xsd:element name="description" type="descriptionType" minOccurs="0" maxOccurs="unbounded"/>
                <xsd:element name="keyword-properties" type="keywordPropertiesType" minOccurs="0" maxOccurs="1">
                    <xsd:annotation>
                        <xsd:appinfo>
                            <jaxb:property name="containerOfListOfKeywordProperties"/>
                        </xsd:appinfo>
                    </xsd:annotation>
                </xsd:element>
                <xsd:element name="positional-properties" type="positionalPropertiesType" minOccurs="0" maxOccurs="1">
                    <xsd:annotation>
                        <xsd:appinfo>
                            <jaxb:property name="containerOfListOfPositionalProperties"/>
                        </xsd:appinfo>
                    </xsd:annotation>
                </xsd:element>
                <xsd:element name="mutual-properties" type="MutualPropertiesType" minOccurs="0" maxOccurs="1"/>
            </xsd:sequence>
            <xsd:attribute name="program-name" type="xsd:string" use="optional"/>
            <xsd:attribute name="properties-file" type="xsd:string" use="optional"/>
            <xsd:attribute name="debug" type="xsd:boolean" use="optional" default="false"/>
            <xsd:attribute name="strict-property-retrieval" type="xsd:boolean" use="optional" default="true"/>
            <xsd:attribute name="strict-command-line" type="xsd:boolean" use="optional" default="true"/>
            <xsd:attribute name="usage" type="xsd:boolean" use="optional" default="false"/>
        </xsd:complexType>
    </xsd:element>

    <xsd:complexType name="PropertyBase" abstract="true">
        <xsd:annotation>
            <xsd:appinfo>
                <jaxb:class name="DummyPropertyBase" implClass="com.mbm.properties.baseclasses.PropertyBase"/>
            </xsd:appinfo>
        </xsd:annotation>
    </xsd:complexType>
    
    <xsd:complexType name="PropertyType" abstract="true">
        <xsd:complexContent>
            <xsd:extension base="PropertyBase">
                <xsd:sequence>
                    <xsd:element name="description" type="descriptionType" minOccurs="0" maxOccurs="unbounded"/>
                    <xsd:element name="forValues" type="forValueType" minOccurs="0" maxOccurs="unbounded"/>
                </xsd:sequence>
                <xsd:attribute name="type" use="required">
                    <xsd:simpleType>
                        <xsd:restriction base="xsd:token">
                            <xsd:enumeration value="integer"/>
                            <xsd:enumeration value="float"/>
                            <xsd:enumeration value="boolean"/>
                            <xsd:enumeration value="string"/>
                        </xsd:restriction>
                    </xsd:simpleType>
                </xsd:attribute>
                <xsd:attribute name="name" type="xsd:string" use="required"/>
                <xsd:attribute name="required" type="xsd:boolean" use="optional" default="false"/>
                <xsd:attribute name="alias" type="xsd:string" use="optional"/>
            </xsd:extension>
        </xsd:complexContent>
    </xsd:complexType>
    
    <xsd:complexType name="keywordPropertiesType">
        <xsd:sequence>
            <xsd:element name="keyword-property" type="keywordPropertyType" minOccurs="1" maxOccurs="unbounded">
                <xsd:annotation>
                    <xsd:appinfo>
                        <jaxb:property name="listOfKeywordProperties"/>
                    </xsd:appinfo>
                </xsd:annotation>
            </xsd:element>
        </xsd:sequence>
    </xsd:complexType>
    
    <xsd:complexType name="keywordPropertyType">
        <xsd:complexContent>
            <xsd:extension base="PropertyType">
                <xsd:sequence>
                    <xsd:element name="challenges" type="ChallengeType" minOccurs="0" maxOccurs="unbounded"/>
                </xsd:sequence>
                <xsd:attribute name="default-value" type="xsd:string" use="optional"/>
                <xsd:attribute name="valid-values" type="xsd:string" use="optional"/>
            </xsd:extension>
        </xsd:complexContent>
    </xsd:complexType>

    <xsd:complexType name="positionalPropertiesType">
        <xsd:sequence>
            <xsd:element name="positional-property" type="positionalPropertyType" minOccurs="1" maxOccurs="unbounded">
                <xsd:annotation>
                    <xsd:appinfo>
                        <jaxb:property name="listOfPositionalProperties"/>
                    </xsd:appinfo>
                </xsd:annotation>
            </xsd:element>
        </xsd:sequence>
    </xsd:complexType>

    <xsd:complexType name="positionalPropertyType">
        <xsd:complexContent>
            <xsd:extension base="PropertyType"/>
        </xsd:complexContent>
    </xsd:complexType>
    
    <xsd:complexType name="ForValueBase" abstract="true">
        <xsd:annotation>
            <xsd:appinfo>
                <jaxb:class name="DummyForValueBase" implClass="com.mbm.properties.baseclasses.ForValueBase"/>
            </xsd:appinfo>
        </xsd:annotation>
    </xsd:complexType>
    
    <xsd:complexType name="forValueType">
        <xsd:complexContent>
            <xsd:extension base="ForValueBase">
                <xsd:sequence>
                    <xsd:element name="description" type="descriptionType" minOccurs="0" maxOccurs="unbounded"/>
                </xsd:sequence>
                <xsd:attribute name="value" type="xsd:string" use="required"/>
                <xsd:attribute name="implies" type="xsd:string" use="optional"/>
            </xsd:extension>
        </xsd:complexContent>
    </xsd:complexType>
    
    <xsd:complexType name="descriptionType">
        <xsd:simpleContent>
            <xsd:extension base="xsd:string">
                <xsd:attribute name="reformat" type="xsd:boolean" use="optional" default="true"/>
                <xsd:attribute name="includeImplies" type="xsd:boolean" use="optional" default="true"/>
            </xsd:extension>
        </xsd:simpleContent>
    </xsd:complexType>

    <xsd:complexType name="ChallengeBase" abstract="true">
        <xsd:annotation>
            <xsd:appinfo>
                <jaxb:class name="DummyChallengeBase" implClass="com.mbm.properties.baseclasses.ChallengeBase"/>
            </xsd:appinfo>
        </xsd:annotation>
    </xsd:complexType>
    
    <xsd:complexType name="ChallengeType" abstract="true">
        <xsd:complexContent>
            <xsd:extension base="ChallengeBase">
                <xsd:attribute name="forValue" type="xsd:string"/>
                <xsd:attribute name="instruction" type="xsd:string"/>
                <xsd:attribute name="passChallengeValue" type="xsd:string"/>
                <xsd:attribute name="failChallengeValue" type="xsd:string" use="optional"/>
            </xsd:extension>
        </xsd:complexContent>
    </xsd:complexType>

    <xsd:complexType name="MutualPropertiesType">
        <xsd:sequence>
            <xsd:element name="mutual-property-set" type="MutualPropertySetType" minOccurs="1" maxOccurs="unbounded"/>
        </xsd:sequence>
    </xsd:complexType>

    <xsd:complexType name="MutualPropertySetBase" abstract="true">
        <xsd:annotation>
            <xsd:appinfo>
                <jaxb:class name="DummyMutualPropertySetBase" implClass="com.mbm.properties.baseclasses.MutualPropertySetBase"/>
            </xsd:appinfo>
        </xsd:annotation>
    </xsd:complexType>

    <xsd:complexType name="MutualPropertySetType">
        <xsd:complexContent>
            <xsd:extension base="MutualPropertySetBase">
                <xsd:sequence>
                    <xsd:element name="mutual-property" type="mutualPropertyType" minOccurs="1" maxOccurs="unbounded"/>
                </xsd:sequence>
                <xsd:attribute name="type" use="required">
                    <xsd:simpleType>
                        <xsd:restriction base="xsd:token">
                            <xsd:enumeration value="inclusive"/>
                            <xsd:enumeration value="exclusive"/>
                        </xsd:restriction>
                    </xsd:simpleType>
                </xsd:attribute>
                <xsd:attribute name="name" type="xsd:string" use="optional"/>
            </xsd:extension>
        </xsd:complexContent>
    </xsd:complexType>

    <xsd:complexType name="mutualPropertyType">
        <xsd:attribute name="name" type="xsd:string" use="required"/>
        <xsd:attribute name="value" type="xsd:string" use="optional"/>
    </xsd:complexType>
</xsd:schema>

XJC 生成了 ObjectClass。请注意，这缺少任何 @XmlElementDecl 属性。

// This file was generated by the Eclipse Implementation of JAXB, v3.0.2 
// See https://eclipse-ee4j.github.io/jaxb-ri 
// Any modifications to this file will be lost upon recompilation of the source schema. 
// Generated on: 2022.01.26 at 10:38:30 AM PST 
//


package com.mbm.properties.jaxb;

import jakarta.xml.bind.annotation.XmlRegistry;


/**
 * This object contains factory methods for each 
 * Java content interface and Java element interface 
 * generated in the com.mbm.properties.jaxb package. 
 * <p>An ObjectFactory allows you to programatically 
 * construct new instances of the Java representation 
 * for XML content. The Java representation of XML 
 * content can consist of schema derived interfaces 
 * and classes representing the binding of schema 
 * type definitions, element declarations and model 
 * groups.  Factory methods for each of these are 
 * provided in this class.
 * 
 */
@XmlRegistry
public class ObjectFactory {


    /**
     * Create a new ObjectFactory that can be used to create new instances of schema derived classes for package: com.mbm.properties.jaxb
     * 
     */
    public ObjectFactory() {
    }

    /**
     * Create an instance of {@link Properties }
     * 
     */
    public Properties createProperties() {
        return new Properties();
    }

    /**
     * Create an instance of {@link DescriptionType }
     * 
     */
    public DescriptionType createDescriptionType() {
        return new DescriptionType();
    }

    /**
     * Create an instance of {@link KeywordPropertiesType }
     * 
     */
    public KeywordPropertiesType createKeywordPropertiesType() {
        return new KeywordPropertiesType();
    }

    /**
     * Create an instance of {@link PositionalPropertiesType }
     * 
     */
    public PositionalPropertiesType createPositionalPropertiesType() {
        return new PositionalPropertiesType();
    }

    /**
     * Create an instance of {@link MutualPropertiesType }
     * 
     */
    public MutualPropertiesType createMutualPropertiesType() {
        return new MutualPropertiesType();
    }

    /**
     * Create an instance of {@link KeywordPropertyType }
     * 
     */
    public KeywordPropertyType createKeywordPropertyType() {
        return new KeywordPropertyType();
    }

    /**
     * Create an instance of {@link PositionalPropertyType }
     * 
     */
    public PositionalPropertyType createPositionalPropertyType() {
        return new PositionalPropertyType();
    }

    /**
     * Create an instance of {@link ForValueType }
     * 
     */
    public ForValueType createForValueType() {
        return new ForValueType();
    }

    /**
     * Create an instance of {@link MutualPropertySetType }
     * 
     */
    public MutualPropertySetType createMutualPropertySetType() {
        return new MutualPropertySetType();
    }

    /**
     * Create an instance of {@link MutualPropertyType }
     * 
     */
    public MutualPropertyType createMutualPropertyType() {
        return new MutualPropertyType();
    }

}

这是尝试解码 XML 的代码。请注意此代码包含此语句 System.out.println(jc.toString());:

package com.mbm.properties;

import java.io.File;
import javax.xml.bind.JAXBContext;
import javax.xml.bind.Unmarshaller;
import com.mbm.properties.jaxb.Properties;

public class Main {
    public static void main(String[] args) {
        try {
            File xmlFile = new File("PropertiesDefinitions.xml");
            JAXBContext jc = JAXBContext.newInstance(Properties.class);
            System.out.println(jc.toString());
            Unmarshaller unmarshaller = jc.createUnmarshaller();
            Properties propertiesDefinitions = (Properties) unmarshaller.unmarshal(xmlFile);
        } catch (Exception e) {
                e.printStackTrace();
                System.exit(1);
        }
    }
}

当这段代码运行时，语句 System.out.println(jc.toString()); 产生这个:

jar:file:/C:/Program%20Files/Java/jdk1.8.0_221/jre/lib/rt.jar!/com/sun/xml/internal/bind/v2/runtime/JAXBContextImpl.class Build-Id: 1.8.0_221
Classes known to this context:
  [B
  boolean
  byte
  char
  com.mbm.properties.jaxb.KeywordPropertiesType
  com.mbm.properties.jaxb.MutualPropertiesType
  com.mbm.properties.jaxb.PositionalPropertiesType
  com.mbm.properties.jaxb.Properties
  com.sun.xml.internal.bind.api.CompositeStructure
  double
  float
  int
  java.awt.Image
  java.io.File
  java.lang.Boolean
  java.lang.Byte
  java.lang.Character
  java.lang.Class
  java.lang.Double
  java.lang.Float
  java.lang.Integer
  java.lang.Long
  java.lang.Object
  java.lang.Short
  java.lang.String
  java.lang.Void
  java.math.BigDecimal
  java.math.BigInteger
  java.net.URI
  java.net.URL
  java.util.Calendar
  java.util.Date
  java.util.GregorianCalendar
  java.util.UUID
  javax.activation.DataHandler
  javax.xml.bind.JAXBElement
  javax.xml.datatype.Duration
  javax.xml.datatype.XMLGregorianCalendar
  javax.xml.namespace.QName
  javax.xml.transform.Source
  long
  short
  void

我很困惑错误指出 unexpected element (uri:"", local:"properties")。预期的元素是(无)。我相信我正在正确创建 JAXB 上下文:

JAXBContext jc = JAXBContext.newInstance(Properties.class);

我正在引用 Properties 类。 Properties.java 包含一个 @XmlRootElement(name = "properties") 元素。 XSD 将properties 标识为一个元素。我所知道的唯一看起来很奇怪的是生成的 ObjectFactory 类缺少任何 @XmlElementDecl 属性。

如果我手动修改 XJC 生成的 ObjectFactory 以包含 @XmlElementDecl 属性:

@XmlRegistry
public class ObjectFactory {
    
    // Begin manually added code
    private final static QName _Properties_QNAME = new QName("", "properties");
    
    @XmlElementDecl(namespace = "", name = "properties")
    public JAXBElement<Properties> createProperties(Properties value) {
        return new JAXBElement<Properties>(_Properties_QNAME, Properties.class, null, value);
    }
    
    // End manually added code

以上修改没有任何区别。我得到了相同的异常。

我做错了什么？

Answer 1

您正在 Main 类中使用 javax.xml.bind.Unmarshaller 的解码器，但您生成的类使用包 jakarta.xml.bind.* 中的注释。在我的案例中，这种不匹配导致了一个非常相似的错误。

修改后重新编译试试

import javax.xml.bind.JAXBContext;
import javax.xml.bind.Unmarshaller;

到

import jakarta.xml.bind.JAXBContext;
import jakarta.xml.bind.Unmarshaller;

在你的主类中。