xsd - XSD 模式和 JAXB 类中的多态性

Question

我有一个这样的xml:

<todo>
    <doLaundry cost="1"/>
    <washCar cost="10"/>
    <tidyBedroom cost="0" experiencePoints="5000"/>
</todo>

它的 XSD 架构是:

<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema">
    <xs:complexType name="todo">
        <xs:sequence>
            <xs:choice maxOccurs="unbounded">
                <xs:element name="doLaundry" type="doLaundry" />
                <xs:element name="washCar" type="washCar" />
                <xs:element name="tidyBedroom" type="tidyBedroom" />
            </xs:choice>
        </xs:sequence>
    </xs:complexType>

    <xs:complexType name="doLaundry">
        <xs:attribute name="cost" type="xs:int" />
    </xs:complexType>

    <xs:complexType name="washCar">
        <xs:attribute name="cost" type="xs:int" />
    </xs:complexType>

    <xs:complexType name="tidyBedroom">
        <xs:attribute name="cost" type="xs:int" />
        <xs:attribute name="experiencePoints" type="xs:int" />
    </xs:complexType>
</xs:schema>

当我通过 JAXB 处理这个模式时，我得到了一个具有如下方法的类:

public class Todo {

    public List<Object> getDoLaundryOrWashCarOrTidyBedroom() {
        ...
    }

}

理想情况下，我想要的是一种定义所有其他 XSD 类型扩展的通用基本类型的方法。从 XSD 模式生成的 Jaxb 类应该具有返回通用任务列表的方法。这将使向待办事项列表添加新任务变得非常容易:

public class Todo {

    public List<Task> getTasks() {
        ...
    }

}

public abstract class Task {
    public int getCost() {
        ...
    }
}

public class TidyBedroom extends Task {
    public int getExperiencePoints() {
        ...
    }
}

为了生成上述 Java 类，XSD 模式应该是什么样的？

Answer 1

我在 Blaise Doughan 的文章的帮助下找到了答案:http://bdoughan.blogspot.com/2010/11/jaxb-and-inheritance-using-xsitype.html

此架构:

<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema">
    <xs:complexType name="todo">
        <xs:sequence>
            <xs:choice maxOccurs="unbounded">
                <xs:element name="doLaundry" type="doLaundry" />
                <xs:element name="washCar" type="washCar" />
                <xs:element name="tidyBedroom" type="tidyBedroom" />
            </xs:choice>
        </xs:sequence>
    </xs:complexType>

    <xs:complexType abstract="true" name="Task">
        <xs:attribute name="cost" type="xs:int" use="required" />
    </xs:complexType>

    <xs:complexType name="doLaundry">
        <xs:complexContent>
            <xs:extension base="Task">
            </xs:extension>
        </xs:complexContent>
    </xs:complexType>

    <xs:complexType name="washCar">
        <xs:complexContent>
            <xs:extension base="Task">
            </xs:extension>
        </xs:complexContent>
    </xs:complexType>

    <xs:complexType name="tidyBedroom">
        <xs:complexContent>
            <xs:extension base="Task">
                <xs:attribute name="experiencePoints" type="xs:int" />
            </xs:extension>
        </xs:complexContent>
    </xs:complexType>

</xs:schema>

结合绑定(bind)文件:

<jxb:bindings version="1.0" xmlns:jxb="http://java.sun.com/xml/ns/jaxb" xmlns:xs="http://www.w3.org/2001/XMLSchema">
    <jxb:bindings>
      <jxb:bindings schemaLocation="todo.xsd" node="/xs:schema/xs:complexType[@name='todo']/xs:sequence/xs:choice">
            <jxb:property name="Tasks"/>
        </jxb:bindings>
    </jxb:bindings>
</jxb:bindings>

正如我在问题中描述的那样，将给出抽象类和继承类。绑定(bind)文件会将 Jaxb 的默认方法名称从 getDoLaundryOrWashCarOrTidyBedroom() 更改为 getTasks()。