继承和 JAXB 如何协同工作？

public abstract class Parent<T> {
    protected List<T> list;

    @XmlTransient   //Question why do we have to give this here?
    public abstract List<T> getList();
    public abstract void setList(List<T> list);
}

@XmlRootElement(name = "child1")
class Child1 extends Parent<ExtendedElement1>{
    @Override
    public void setList(List<ExtendedElement1> list){
        this.list = list;
    }

    @Override
    @XmlElementWrapper(name = "child1-list")
    @XmlElement(name = "child-list-element")
    public List<ExtendedElement1> getList(){
        return this.list;
    }
}

@XmlRootElement(name = "child2")
class Child2 extends Parent<ExtendedElement2>{
    @Override
    public void setList(List<ExtendedElement2> list){
        this.list = list;
    }

    @Override
    @XmlElementWrapper(name = "child1-list")
    @XmlElement(name = "child-list-element")
    public List<ExtendedElement2> getList(){
        return this.list;
    }
}


class Element{
    @XmlElement(name = "integer", type = int.class)
    private int i = 2;
}

class ExtendedElement1 extends Element{
    @XmlElement(name = "extended-element1-str", type = String.class)
    private String str = "hello";
}

class ExtendedElement2 extends Element{
    @XmlElement(name = "extended-element2-str", type = String.class)
    private String str1 = "hello_there";
}

正如我在示例中演示的那样，当我删除 from the class 方法时，以下 xml 被封送：@XmlTransientParentgetList()

<child1>
<!-- List is serialized 2 times -->
    <list xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:type="extendedElement1">
        <integer>2</integer>
        <extended-element1-str>hello</extended-element1-str>
    </list>
    <list xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:type="extendedElement1">
        <integer>2</integer>
        <extended-element1-str>hello</extended-element1-str>
    </list>
    <list xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:type="extendedElement1">
        <integer>2</integer>
        <extended-element1-str>hello</extended-element1-str>
    </list>
    <child1-list>
        <child-list-element>
            <integer>2</integer>
            <extended-element1-str>hello</extended-element1-str>
        </child-list-element>
        <child-list-element>
            <integer>2</integer>
            <extended-element1-str>hello</extended-element1-str>
        </child-list-element>
        <child-list-element>
            <integer>2</integer>
            <extended-element1-str>hello</extended-element1-str>
        </child-list-element>
    </child1-list>
</child1>

但是，当我添加注释时，如示例中所示，xml 被序列化，仅在需要时使用一个列表。@XmlTransient

<child1>
    <child1-list>
        <child-list-element>
            <integer>2</integer>
            <extended-element1-str>hello</extended-element1-str>
        </child-list-element>
        <child-list-element>
            <integer>2</integer>
            <extended-element1-str>hello</extended-element1-str>
        </child-list-element>
        <child-list-element>
            <integer>2</integer>
            <extended-element1-str>hello</extended-element1-str>
        </child-list-element>
    </child1-list>
</child1>

所以请有人解释一下为什么需要在父类getter方法中给出？在这些情况下，继承和 JAXB 如何相互关联？@XmlTransient