jaxb - 如何从多态类创建 XML

使用JAXB库可以将Java对象映射为XML文档，并且通过多态类的方式来创建XML文档。在本文中，我们将探讨如何使用JAXB从多态类创建XML，并提供一个案例代码来进行说明。

public class Animal {
    // 省略其他属性和方法
}
public class Cat extends Animal {
    // 省略其他属性和方法
}
public class Dog extends Animal {
    // 省略其他属性和方法
}
List animals = new ArrayList<>();
animals.add(new Cat());
animals.add(new Dog());

@XmlRegistry
public class ObjectFactory {
    public Animal createAnimal() {
        return new Animal();
    }
    public Cat createCat() {
        return new Cat();
    }
    public Dog createDog() {
        return new Dog();
    }
}

JAXBContext context = JAXBContext.newInstance(ObjectFactory.class, Animal.class, Cat.class, Dog.class);
Marshaller marshaller = context.createMarshaller();
marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);
ListWrapper wrapper = new ListWrapper();
wrapper.setAnimals(animals);
marshaller.marshal(wrapper, new File("animals.xml"));

@XmlRootElement
public class ListWrapper {
    private List animals;
    @XmlElementRef
    public List getAnimals() {
        return animals;
    }
    public void setAnimals(List animals) {
        this.animals = animals;
    }
}

xml
    
        
    
    
        
    

java
import javax.xml.bind.JAXBContext;
import javax.xml.bind.JAXBException;
import javax.xml.bind.Marshaller;
import javax.xml.bind.annotation.XmlElementRef;
import javax.xml.bind.annotation.XmlRegistry;
import javax.xml.bind.annotation.XmlRootElement;
import java.io.File;
import java.util.ArrayList;
import java.util.List;
public class PolymorphicXMLCreationExample {
    public static void main(String[] args) {
        List animals = new ArrayList<>();
        animals.add(new Cat());
        animals.add(new Dog());
        try {
            JAXBContext context = JAXBContext.newInstance(ObjectFactory.class, Animal.class, Cat.class, Dog.class);
            Marshaller marshaller = context.createMarshaller();
            marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);
            ListWrapper wrapper = new ListWrapper();
            wrapper.setAnimals(animals);
            marshaller.marshal(wrapper, new File("animals.xml"));
        } catch (JAXBException e) {
            e.printStackTrace();
        }
    }
    public static class Animal {
        // 省略其他属性和方法
    }
    public static class Cat extends Animal {
        // 省略其他属性和方法
    }
    public static class Dog extends Animal {
        // 省略其他属性和方法
    }
    @XmlRootElement
    public static class ListWrapper {
        private List animals;
        @XmlElementRef
        public List getAnimals() {
            return animals;
        }
        public void setAnimals(List animals) {
            this.animals = animals;
        }
    }
    @XmlRegistry
    public static class ObjectFactory {
        public Animal createAnimal() {
            return new Animal();
        }
        public Cat createCat() {
            return new Cat();
        }
        public Dog createDog() {
            return new Dog();
        }
    }
}