MOXY中的JAXB繼承

Question

我有兩節課：

package a;
class A {
 private <type> fieldOfClassA;
 // getters, and setters
}

package b;
class B extends A{
 private <type> fieldOfClassB;
 // getters, and setters
}

我想將類B編組為xml元素，並添加屬性fieldOfClassB和類A的fieldOfClassA，但在編組期間會顯示以下警告消息：

Ignoring attribute [fieldOfClassA] on class [b.B] as no Property was generated for it.

請注意，這兩個類來自兩個不同的程序包，我無法更改此對象模型。

先感謝您！

編輯：

我正在使用外部綁定文件。

Answer 1

從您發布的日志消息中，我可以看到您正在使用MOXy的外部映射文檔（請參閱http://blog.bdoughan.com/2010/12/extending-jaxb-representing-annotations.html ）。 有兩種不同的方法來映射繼承的屬性。

---

選項＃1-映射屬於父級的繼承屬性

默認情況下，字段/屬性需要映射到它所屬的類中。 由於MOXy在包級別作用域外部映射文檔，因此您將需要A和B單獨映射文檔。

Forum10874711 / a / binding1.xml

<?xml version="1.0"?>
<xml-bindings
    xmlns="http://www.eclipse.org/eclipselink/xsds/persistence/oxm"
    package-name="forum10874711.a">
    <java-types>
        <java-type name="A">
            <java-attributes>
                <xml-element java-attribute="fieldOfClassA" name="field-of-class-a"/>
            </java-attributes>
        </java-type>
    </java-types>
</xml-bindings>

Forum10874711 / b / binding1.xml

<?xml version="1.0"?>
<xml-bindings
    xmlns="http://www.eclipse.org/eclipselink/xsds/persistence/oxm"
    package-name="forum10874711.b">
    <java-types>
        <java-type name="B">
            <xml-root-element/>
            <java-attributes>
                <xml-element java-attribute="fieldOfClassB" name="field-of-class-b"/>
            </java-attributes>
        </java-type>
    </java-types>
</xml-bindings>

Forum10874711 / b / jaxb.properties

要將MOXy指定為JAXB實現，您需要在與域模型相同的包中添加一個名為jaxb.properties的文件，並帶有以下條目。

javax.xml.bind.context.factory=org.eclipse.persistence.jaxb.JAXBContextFactory

演示版

package forum10874711;

import java.util.*;
import javax.xml.bind.*;
import org.eclipse.persistence.jaxb.JAXBContextFactory;

import forum10874711.b.B;

public class Demo1 {

    public static void main(String[] args) throws Exception {
        Map<String, Object> properties = new HashMap<String, Object>(1);
        List<String> metadata = new ArrayList<String>(2);
        metadata.add("forum10874711/a/binding1.xml");
        metadata.add("forum10874711/b/binding1.xml");
        properties.put(JAXBContextFactory.ECLIPSELINK_OXM_XML_KEY, metadata);
        JAXBContext jc = JAXBContext.newInstance(new Class[] {B.class}, properties);

        B b = new B();
        b.setFieldOfClassA("foo");
        b.setFieldOfClassB(123);

        Marshaller marshaller = jc.createMarshaller();
        marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);
        marshaller.marshal(b, System.out);
    }

}

輸出量

<?xml version="1.0" encoding="UTF-8"?>
<b>
   <field-of-class-a>foo</field-of-class-a>
   <field-of-class-b>123</field-of-class-b>
</b>

---

選項＃2-映射屬於子級的繼承屬性

可以將父類A' can be marked @XmlTransient， this will allow us to map the inherited fields/properties on the child class B` this will allow us to map the inherited fields/properties on the child class （請參見http://blog.bdoughan.com/2011/06/ignoring-inheritance-with-xmltransient .html ）。

Forum10874711 / a / binding2.xml

<?xml version="1.0"?>
<xml-bindings
    xmlns="http://www.eclipse.org/eclipselink/xsds/persistence/oxm"
    package-name="forum10874711.a">
    <java-types>
        <java-type name="A" xml-transient="true"/>
    </java-types>
</xml-bindings>

Forum10874711 / b / binding2.xml

<?xml version="1.0" encoding="UTF-8"?>
<xml-bindings
    xmlns="http://www.eclipse.org/eclipselink/xsds/persistence/oxm"
    package-name="forum10874711.b">
    <java-types>
        <java-type name="B">
            <xml-root-element/>
            <java-attributes>
                <xml-element java-attribute="fieldOfClassA" name="field-of-class-a"/>
                <xml-element java-attribute="fieldOfClassB" name="field-of-class-b"/>
            </java-attributes>
        </java-type>
    </java-types>
</xml-bindings>

演示版

package forum10874711;

import java.util.*;
import javax.xml.bind.*;
import org.eclipse.persistence.jaxb.JAXBContextFactory;

import forum10874711.b.B;

public class Demo2 {

    public static void main(String[] args) throws Exception {
        Map<String, Object> properties = new HashMap<String, Object>(1);
        List<String> metadata = new ArrayList<String>(2);
        metadata.add("forum10874711/a/binding2.xml");
        metadata.add("forum10874711/b/binding2.xml");
        properties.put(JAXBContextFactory.ECLIPSELINK_OXM_XML_KEY, metadata);
        JAXBContext jc = JAXBContext.newInstance(new Class[] {B.class}, properties);

        B b = new B();
        b.setFieldOfClassA("foo");
        b.setFieldOfClassB(123);

        Marshaller marshaller = jc.createMarshaller();
        marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);
        marshaller.marshal(b, System.out);
    }

}

輸出量

<?xml version="1.0" encoding="UTF-8"?>
<b>
   <field-of-class-a>foo</field-of-class-a>
   <field-of-class-b>123</field-of-class-b>
</b>