使用 JAXB 类使用解组时出错

Question

我已经从以下 xsd 模式生成了 JAXB 类：

    <?xml version="1.0" encoding="UTF-8"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema">
    <xs:element name="MeetUpData">
        <xs:complexType>
            <xs:sequence>
                <xs:element maxOccurs="unbounded" name="SessionData">
                    <xs:complexType>
                        <xs:attribute name="Date" type="xs:string" use="required" />
                        <xs:attribute name="Quantity" type="xs:int" use="required" />
                        <xs:attribute name="Theme" type="xs:string" use="required" />
                    </xs:complexType>
                </xs:element>
            </xs:sequence>
            <xs:attribute name="Name" type="xs:string" use="required" />
            <xs:attribute name="Location" type="xs:string" use="required" />
        </xs:complexType>
    </xs:element>
</xs:schema>

现在我正在尝试解组以下 XML 文档

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<MeetUpData>
    <location>3</location>
    <name>2</name>
    <sessionsData>
        <date>345</date>
        <quantity>3</quantity>
        <theme>Windows</theme>
    </sessionsData>
    <sessionsData>
        <date>3</date>
        <quantity>7</quantity>
        <theme>9</theme>
    </sessionsData>
</MeetUpData>

通过以下代码：

JAXBContext jc = JAXBContext.newInstance(MeetUp.class);
            Unmarshaller ums = jc.createUnmarshaller();
            meetUpData = (MeetUpData) ums.unmarshal(new FileInputStream("src\\com\\bases\\java\\InitialXML.xml"));
            System.out.println("Info: " + meetUpData.toString());

但是我得到了一堆错误：

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

有什么问题？

Answer 1

我不知道您的 java 类是什么样子，但是根据错误消息，您没有使用 @XMLRootElement 注释根类。

我已经使用 MeetUpData 类更改了 JAXB 的实例化，并使用 @XMLRootElement 对其进行了注释。

这里是函数来源

MeetUpData.class：

import java.io.Serializable;
import java.util.List;

import javax.xml.bind.annotation.XmlRootElement;

@XmlRootElement
public class MeetUpData implements Serializable {

    private static final long serialVersionUID = 1L;
    String location;
    String name;
    List<SessionData> sessionsData;

    public MeetUpData() {
        super();
    }

    public String getLocation() {
        return location;
    }

    public void setLocation(String location) {
        this.location = location;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public List<SessionData> getSessionsData() {
        return sessionsData;
    }

    public void setSessionsData(List<SessionData> sessionsData) {
        this.sessionsData = sessionsData;
    }

    @Override
    public String toString() {
        return "MeetUpData [location=" + location + ", name=" + name + ", sessionData=" + sessionsData + "]";
    }

}

要解组的代码：

JAXBContext jc = JAXBContext.newInstance(MeetUpData.class);
Unmarshaller ums = jc.createUnmarshaller();
MeetUpData meetUpData = (MeetUpData) ums.unmarshal(new FileInputStream(
               "src\\com\\bases\\java\\InitialXML.xml"));
System.out.println("Info: " + meetUpData.toString());

此外，您需要将 XML 中的“MeetUpData”标记更改为以小写“m”开头，如下所示：

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<meetUpData>
    <location>3</location>
    <name>2</name>
    <sessionsData>
        <date>345</date>
        <quantity>3</quantity>
        <theme>Windows</theme>
    </sessionsData>
    <sessionsData>
        <date>3</date>
        <quantity>7</quantity>
        <theme>9</theme>
    </sessionsData>
</meetUpData>

如果这不适合您，请提供您的课程。

Answer 2

只尝试最后两行：

meetUpData = (MeetUpData) ums.unmarshal(new FileInputStream("src\\com\\bases\\java\\InitialXML.xml"));
        System.out.println("Info: " + meetUpData.toString());