在JAXBContext中將XML轉換為Class的一些問題

Question

我正在使用JAXBContext將XML轉換為Class。

但是我有問題

1）XML這樣。

<Baseball namespace="Sport">
<League namespace="MLB">
  <Description>Baseball league of America</Description>
  <Team>
     <Name>Yankees</Name>
     <City>Newyork</City>
  </Team>
  <Team>
     <Name>Dodgers</Name>
     <City>LA</City>
  </Team>
</League>
</Baseball>

2）像這樣的課。

2-1）棒球課

@XmlRootElement(name = "Baseball ", namespace = "Sport")
@XmlAccessorType(XmlAccessType.FIELD)
private class Baseball
{
   @XmlElement(name = "League", namespace = "MLB")
   public League league;
}

2-2）聯賽

@XmlRootElement
@XmlAccessorType(XmlAccessType.FIELD)
private class League
{
   @XmlElement(name = "Description")
   public String description;

   @XmlElement(name = "Team")
   public Team[] teams;
}

2-3）團隊班

@XmlRootElement
@XmlAccessorType(XmlAccessType.FIELD)
private class Team
{
   @XmlElement(name = "Name")
   public String name;
   @XmlElement(name = "City")
   public String city;
}

棒球和聯賽已成功轉換為職業，但球隊未轉換為職業。

description的值也為null。

這段代碼有什么問題？

Answer 1

您的xml無效。
元素“描述”由開始標簽而不是結束標簽終止。
此外，“聯盟”缺少結束標簽。

這是xml的有效版本：

<Baseball namespace="Sport">
<League namespace="MLB">
  <Description>Baseball league of America</Description>
  <Team>
     <Name>Yankees</Name>
     <City>Newyork</City>
  </Team>
  <Team>
     <Name>Dodgers</Name>
     <City>LA</City>
  </Team>
</League>
</Baseball>

Answer 2

我使用此鏈接從您的（更正后的）示例XML中生成了XSD文件，並使用xjc從中生成了類。
我附上了結果，因此您可以將其與您的班級進行比較以了解差異。

Baseball.java：

//
// This file was generated by the JavaTM Architecture for XML Binding(JAXB) Reference Implementation, v2.2.8-b130911.1802 
// See <a href="http://java.sun.com/xml/jaxb">http://java.sun.com/xml/jaxb</a> 
// Any modifications to this file will be lost upon recompilation of the source schema. 
// Generated on: 2018.10.15 at 12:07:59 PM IDT 
//


package generated;

import javax.xml.bind.annotation.XmlAccessType;
import javax.xml.bind.annotation.XmlAccessorType;
import javax.xml.bind.annotation.XmlAttribute;
import javax.xml.bind.annotation.XmlElement;
import javax.xml.bind.annotation.XmlRootElement;
import javax.xml.bind.annotation.XmlType;


/**
 * <p>Java class for anonymous complex type.
 * 
 * <p>The following schema fragment specifies the expected content contained within this class.
 * 
 * <pre>
 * &lt;complexType>
 *   &lt;complexContent>
 *     &lt;restriction base="{http://www.w3.org/2001/XMLSchema}anyType">
 *       &lt;sequence>
 *         &lt;element ref="{}League"/>
 *       &lt;/sequence>
 *       &lt;attribute name="namespace" type="{http://www.w3.org/2001/XMLSchema}string" />
 *     &lt;/restriction>
 *   &lt;/complexContent>
 * &lt;/complexType>
 * </pre>
 * 
 * 
 */
@XmlAccessorType(XmlAccessType.FIELD)
@XmlType(name = "", propOrder = {
    "league"
})
@XmlRootElement(name = "Baseball")
public class Baseball {

    @XmlElement(name = "League", required = true)
    protected League league;
    @XmlAttribute(name = "namespace")
    protected String namespace;

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

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

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

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

}

League.java：

//
// This file was generated by the JavaTM Architecture for XML Binding(JAXB) Reference Implementation, v2.2.8-b130911.1802 
// See <a href="http://java.sun.com/xml/jaxb">http://java.sun.com/xml/jaxb</a> 
// Any modifications to this file will be lost upon recompilation of the source schema. 
// Generated on: 2018.10.15 at 12:07:59 PM IDT 
//


package generated;

import java.util.ArrayList;
import java.util.List;
import javax.xml.bind.annotation.XmlAccessType;
import javax.xml.bind.annotation.XmlAccessorType;
import javax.xml.bind.annotation.XmlAttribute;
import javax.xml.bind.annotation.XmlElement;
import javax.xml.bind.annotation.XmlRootElement;
import javax.xml.bind.annotation.XmlType;


/**
 * <p>Java class for anonymous complex type.
 * 
 * <p>The following schema fragment specifies the expected content contained within this class.
 * 
 * <pre>
 * &lt;complexType>
 *   &lt;complexContent>
 *     &lt;restriction base="{http://www.w3.org/2001/XMLSchema}anyType">
 *       &lt;sequence>
 *         &lt;element ref="{}Description"/>
 *         &lt;element ref="{}Team" maxOccurs="unbounded" minOccurs="0"/>
 *       &lt;/sequence>
 *       &lt;attribute name="namespace" type="{http://www.w3.org/2001/XMLSchema}string" />
 *     &lt;/restriction>
 *   &lt;/complexContent>
 * &lt;/complexType>
 * </pre>
 * 
 * 
 */
@XmlAccessorType(XmlAccessType.FIELD)
@XmlType(name = "", propOrder = {
    "description",
    "team"
})
@XmlRootElement(name = "League")
public class League {

    @XmlElement(name = "Description", required = true)
    protected String description;
    @XmlElement(name = "Team")
    protected List<Team> team;
    @XmlAttribute(name = "namespace")
    protected String namespace;

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

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

    /**
     * Gets the value of the team property.
     * 
     * <p>
     * This accessor method returns a reference to the live list,
     * not a snapshot. Therefore any modification you make to the
     * returned list will be present inside the JAXB object.
     * This is why there is not a <CODE>set</CODE> method for the team property.
     * 
     * <p>
     * For example, to add a new item, do as follows:
     * <pre>
     *    getTeam().add(newItem);
     * </pre>
     * 
     * 
     * <p>
     * Objects of the following type(s) are allowed in the list
     * {@link Team }
     * 
     * 
     */
    public List<Team> getTeam() {
        if (team == null) {
            team = new ArrayList<Team>();
        }
        return this.team;
    }

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

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

}

Team.java：

//
// This file was generated by the JavaTM Architecture for XML Binding(JAXB) Reference Implementation, v2.2.8-b130911.1802 
// See <a href="http://java.sun.com/xml/jaxb">http://java.sun.com/xml/jaxb</a> 
// Any modifications to this file will be lost upon recompilation of the source schema. 
// Generated on: 2018.10.15 at 12:07:59 PM IDT 
//


package generated;

import javax.xml.bind.annotation.XmlAccessType;
import javax.xml.bind.annotation.XmlAccessorType;
import javax.xml.bind.annotation.XmlElement;
import javax.xml.bind.annotation.XmlRootElement;
import javax.xml.bind.annotation.XmlType;


/**
 * <p>Java class for anonymous complex type.
 * 
 * <p>The following schema fragment specifies the expected content contained within this class.
 * 
 * <pre>
 * &lt;complexType>
 *   &lt;complexContent>
 *     &lt;restriction base="{http://www.w3.org/2001/XMLSchema}anyType">
 *       &lt;sequence>
 *         &lt;element ref="{}Name"/>
 *         &lt;element ref="{}City"/>
 *       &lt;/sequence>
 *     &lt;/restriction>
 *   &lt;/complexContent>
 * &lt;/complexType>
 * </pre>
 * 
 * 
 */
@XmlAccessorType(XmlAccessType.FIELD)
@XmlType(name = "", propOrder = {
    "name",
    "city"
})
@XmlRootElement(name = "Team")
public class Team {

    @XmlElement(name = "Name", required = true)
    protected String name;
    @XmlElement(name = "City", required = true)
    protected String city;

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

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

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

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

}

ObjectFactory.java：

//
// This file was generated by the JavaTM Architecture for XML Binding(JAXB) Reference Implementation, v2.2.8-b130911.1802 
// See <a href="http://java.sun.com/xml/jaxb">http://java.sun.com/xml/jaxb</a> 
// Any modifications to this file will be lost upon recompilation of the source schema. 
// Generated on: 2018.10.15 at 12:07:59 PM IDT 
//


package generated;

import javax.xml.bind.JAXBElement;
import javax.xml.bind.annotation.XmlElementDecl;
import javax.xml.bind.annotation.XmlRegistry;
import javax.xml.namespace.QName;


/**
 * This object contains factory methods for each 
 * Java content interface and Java element interface 
 * generated in the generated 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 {

    private final static QName _Description_QNAME = new QName("", "Description");
    private final static QName _City_QNAME = new QName("", "City");
    private final static QName _Name_QNAME = new QName("", "Name");

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

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

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

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

    /**
     * Create an instance of {@link JAXBElement }{@code <}{@link String }{@code >}}
     * 
     */
    @XmlElementDecl(namespace = "", name = "Description")
    public JAXBElement<String> createDescription(String value) {
        return new JAXBElement<String>(_Description_QNAME, String.class, null, value);
    }

    /**
     * Create an instance of {@link JAXBElement }{@code <}{@link String }{@code >}}
     * 
     */
    @XmlElementDecl(namespace = "", name = "City")
    public JAXBElement<String> createCity(String value) {
        return new JAXBElement<String>(_City_QNAME, String.class, null, value);
    }

    /**
     * Create an instance of {@link JAXBElement }{@code <}{@link String }{@code >}}
     * 
     */
    @XmlElementDecl(namespace = "", name = "Name")
    public JAXBElement<String> createName(String value) {
        return new JAXBElement<String>(_Name_QNAME, String.class, null, value);
    }

}