使用JaxB编组实现公共接口的对象列表

Question

我正在尝试编组实现通用接口的对象列表.涉及3个类和1个接口:

社区类(有一个方法:List <Person> getPeople();)

Person接口(有一个方法:String getName();)

女子班(实施人)

男生班(实施人)

见下面的代码.

我想要一个看起来像这样的XML:

<community>
  <people>
    <girl>
      <name>Jane</name>
    </girl>
    <boy>
      <name>John</name>
    </boy>
    <girl>
      <name>Jane</name>
    </girl>
    <boy>
      <name>John</name>
    </boy>
  </people>
</community>

或者可能:

<community>
  <people>
   <person>
      <girl>
        <name>Jane</name>
      </girl>
    </person>
    <person>
      <boy>
        <name>John</name>
      </boy>
    </person>
  </people>
</community>

到目前为止,我得到的是:

<community>
    <people>
        <person xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:type="girl">
            <name>Jane</name>
        </person>
        <person xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:type="boy">
            <name>John</name>
        </person>
        <person xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:type="girl">
            <name>Jane</name>
        </person>
        <person xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:type="boy">
            <name>John</name>
        </person>
    </people>
</community>

我意识到我可以将元素更改为其他内容,但我希望元素名称是Girl或Boy类中的名称.

可以这样做吗？谢谢.

@XmlRootElement(name = "community")
public class Community {

 private List<Person> people;

 @XmlElementWrapper
 @XmlElement(name="person")
 public List<Person> getPeople() {
  return people;
 }

 public Community() {
  people = new ArrayList<Person>();
  people.add(new Girl());
  people.add(new Boy());
  people.add(new Girl());
  people.add(new Boy());
 }
}







@XmlRootElement(name = "girl")
public class Girl implements Person {

 @XmlElement
 public String getName() {
  return "Jane";
 }
}


@XmlRootElement(name = "boy")
public class Boy implements Person {

 @XmlElement
 public String getName() {
  return "John";
 }
}



@XmlJavaTypeAdapter(AnyTypeAdapter.class)
public interface Person {
 public String getName();
}



public class AnyTypeAdapter extends XmlAdapter<Object, Object> {

 @Override
   public Object marshal(Object v) throws Exception {
    return v;
   }

 @Override
   public Object unmarshal(Object v) throws Exception {
    return v;
   }

}

Answer 1

对于这种情况,我建议使用@XmlElements.@XmlElements用于表示选择的XML模式概念:

• http://bdoughan.blogspot.com/2010/10/jaxb-and-xsd-choice-xmlelements.html

以下是它如何查找您的示例:

@XmlElements({ 
    @XmlElement(name="girl", type=Girl.class),
    @XmlElement(name="boy", type=Boy.class)
})
@XmlElementWrapper
public List<Person> getPeople() {
    return people;
}

@XmlElementRef对应于XML模式中的替换组的概念.这就是为什么之前的答案需要将Person从接口更改为类.

• http://bdoughan.blogspot.com/2010/11/jaxb-and-inheritance-using-substitution.html

Answer 2

好的,如果您准备将Person从界面更改为抽象基类,那么您就是金色的.这是代码:

public class Main {


  public static void main(String[] args) throws Exception {

    Community community = new Community();

    JAXBContext context = JAXBContext.newInstance(Community.class);
    Marshaller marshaller = context.createMarshaller();
    marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);
    marshaller.marshal(community, System.out);

  }
}

@XmlRootElement(name = "community")
@XmlSeeAlso({Person.class})
public class Community {

 private List<Person> people;

 @XmlElementWrapper(name="people")
 @XmlElementRef()
 public List<Person> getPeople() {
  return people;
 }

 public Community() {
  people = new ArrayList<Person>();
  people.add(new Girl());
  people.add(new Boy());
  people.add(new Girl());
  people.add(new Boy());
 }
}

@XmlRootElement(name="boy")
public class Boy extends Person {

 public String getName() {
  return "John";
 }
}

@XmlRootElement(name="girl")
public class Girl extends Person {

 public String getName() {
  return "Jane";
 }
}

@XmlRootElement(name = "person")
@XmlSeeAlso({Girl.class,Boy.class})
public abstract class Person {

  @XmlElement(name="name")
 public abstract String getName();
}

主要技巧是在社区列表中使用@XmlElementRef.这通过它的@XmlRootElement标识类的类型.您可能也对@XmlSeeAlso感兴趣,它有助于组织上下文声明.

输出是

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<community>
    <people>
        <girl>
            <name>Jane</name>
        </girl>
        <boy>
            <name>John</name>
        </boy>
        <girl>
            <name>Jane</name>
        </girl>
        <boy>
            <name>John</name>
        </boy>
    </people>
</community>