从您发布的日志信息中,我可以看出您正在使用MOXy的外部映射文档(请参见
http://blog.bdoughan.com/2010/12/extending-jaxb-representing-annotations.html)。有几种不同的方法可以映射继承属性。
选项1 - 映射属于父类的继承属性
默认情况下,字段/属性需要在其所属的类中进行映射。由于MOXy将外部映射文档作用域限定在包级别,因此您需要为A
和B
编写不同的映射文档。
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
如果你想使用MOXy作为你的JAXB实现,你需要在与你的领域模型相同的包中添加一个名为jaxb.properties
的文件,并加入以下内容。
javax.xml.bind.context.factory=org.eclipse.persistence.jaxb.JAXBContextFactory
演示
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);
}
}
输出
<?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>
选项 #2 - 映射属于子类的继承属性
父类 A
可以被标记为 @XmlTransient
,这使得我们能够在子类 B
上映射继承的字段/属性(参见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
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);
}
}
输出
<?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>