JAXB-解組XML文件

Question

我嘗試解組具有以下結構的xml文件：

<?xml version="1.0" encoding="UTF-8"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema">
<xs:element name="map">
    <xs:complexType>
        <xs:sequence>
            <xs:element name="country" maxOccurs="unbounded">
                <xs:complexType>
                    <xs:sequence>
                        <xs:element name="name" type="xs:string" />
                        <xs:element name="x" type="xs:integer" />
                        <xs:element name="y" type="xs:integer" />
                    </xs:sequence>
                </xs:complexType>
            </xs:element>
        </xs:sequence>
        <xs:attribute name="name" type="xs:string" use="required" />
    </xs:complexType>
</xs:element>

一個例子是：

<?xml version="1.0" encoding="UTF-8"?>

<map name="usa" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:noNamespaceSchemaLocation="field.xsd">
<country>
    <name>Test1</name>
    <x>110</x>
    <y>20</y>
</country>
<country>
    <name>Test2</name>
    <x>200</x>
    <y>30</y>
</country>
<country>
    <name>Test3</name>
    <x>350</x>
    <y>80</y>
</country>
</map>

為此，我創建了以下類：

package game.view.gui;

public class ObjectFactory {

    public ObjectFactory() {
    }

    public Map createMap() {
        return new Map();
    }
}

和

package game.view.gui;

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;

@XmlAccessorType(XmlAccessType.FIELD)
@XmlRootElement( name = "map" )
public class Map {
@XmlAttribute
private String name;
private List<Country> countries = new ArrayList<Country>();

@XmlElement( name = "country" )
public List<Country> getCountries() {
    return countries;
}

public void setCountries( List<Country> countries ) {
    this.countries = countries;
}
}

和

package game.view.gui;

import javax.xml.bind.annotation.XmlElement;
import javax.xml.bind.annotation.XmlRootElement;

@XmlRootElement(name = "country")
public class Country {
    @XmlElement(required = true)
    private String name;
    @XmlElement(required = true)
    private int x;
    @XmlElement(required = true)
    private int y;

    public String getName() {
        return name;
    }

    public int getX() {
        return x;
    }

    public int getY() {
        return y;
    }
}

我總是遇到一個異常，在該異常中，xml似乎不適合所創建的pojos。 我試圖做到與閱讀的教程相同。 異常出現在以下代碼行中：

 Map map = (Map) unmarsh.unmarshal(file);

您能告訴我我需要在pojos中進行哪些更改以確保一切正常嗎？

Edit1：例外：

javax.xml.bind.UnmarshalException: unexpected element (uri:"", local:"map"). Expected elements are (none)
at com.sun.xml.internal.bind.v2.runtime.unmarshaller.UnmarshallingContext.handleEvent(Unknown Source)
at com.sun.xml.internal.bind.v2.runtime.unmarshaller.Loader.reportError(Unknown Source)
at com.sun.xml.internal.bind.v2.runtime.unmarshaller.Loader.reportError(Unknown Source)
at com.sun.xml.internal.bind.v2.runtime.unmarshaller.Loader.reportUnexpectedChildElement(Unknown Source)
at com.sun.xml.internal.bind.v2.runtime.unmarshaller.UnmarshallingContext$DefaultRootLoader.childElement(Unknown Source)
at com.sun.xml.internal.bind.v2.runtime.unmarshaller.UnmarshallingContext._startElement(Unknown Source)
at com.sun.xml.internal.bind.v2.runtime.unmarshaller.UnmarshallingContext.startElement(Unknown Source)
at com.sun.xml.internal.bind.v2.runtime.unmarshaller.SAXConnector.startElement(Unknown Source)
at com.sun.org.apache.xerces.internal.parsers.AbstractSAXParser.startElement(Unknown Source)
at com.sun.org.apache.xerces.internal.impl.XMLNSDocumentScannerImpl.scanStartElement(Unknown Source)
at com.sun.org.apache.xerces.internal.impl.XMLNSDocumentScannerImpl$NSContentDriver.scanRootElementHook(Unknown Source)
at com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl$FragmentContentDriver.next(Unknown Source)
at com.sun.org.apache.xerces.internal.impl.XMLDocumentScannerImpl$PrologDriver.next(Unknown Source)
at com.sun.org.apache.xerces.internal.impl.XMLDocumentScannerImpl.next(Unknown Source)
at com.sun.org.apache.xerces.internal.impl.XMLNSDocumentScannerImpl.next(Unknown Source)
at com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl.scanDocument(Unknown Source)
at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(Unknown Source)
at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(Unknown Source)
at com.sun.org.apache.xerces.internal.parsers.XMLParser.parse(Unknown Source)
at com.sun.org.apache.xerces.internal.parsers.AbstractSAXParser.parse(Unknown Source)
at com.sun.org.apache.xerces.internal.jaxp.SAXParserImpl$JAXPSAXParser.parse(Unknown Source)
at com.sun.xml.internal.bind.v2.runtime.unmarshaller.UnmarshallerImpl.unmarshal0(Unknown Source)
at com.sun.xml.internal.bind.v2.runtime.unmarshaller.UnmarshallerImpl.unmarshal(Unknown Source)
at javax.xml.bind.helpers.AbstractUnmarshallerImpl.unmarshal(Unknown Source)
at javax.xml.bind.helpers.AbstractUnmarshallerImpl.unmarshal(Unknown Source)
at javax.xml.bind.helpers.AbstractUnmarshallerImpl.unmarshal(Unknown Source)
at javax.xml.bind.helpers.AbstractUnmarshallerImpl.unmarshal(Unknown Source)

Answer 1

創建JAXBContext （用於創建marshaller和unmarshaller實例）時，您需要傳遞架構的根類-通常，它們將使用@XmlType和/或@XmlRootElement進行標記，以便上下文知道哪個正在使用的類。 它不執行的操作是關閉並掃描您的類路徑上的所有類，以免它們可能有某些相關的要說的機會。 那會非常昂貴！

實際上，更改：

JAXBContext.newInstance();

至：

JAXBContext.newInstance(Map.class);

您可能還需要在注釋中顯式指定名稱空間映射（到空名稱空間）（例如，通過@XmlRootElement注釋的namespace字段），並且我發現調試JAXB上下文的最簡單方法通常是生成模式他們通過generateSchema方法進行編碼（帶有偽輸出解析器，該偽輸出解析器僅使它們轉儲到System.out …）

Answer 2

您創建的ObjectFactory類缺少必需的@XmlRegistry批注。 沒有此注釋， ObjectFactory將被視為常規域對象。