JAXB 生成的 xml 中的“xsitype”和“xmlnsxsi”

JAXB是Java Architecture for XML Binding的缩写，它是一个用于将Java对象与XML文档进行互相转换的框架。在使用JAXB生成的XML文档中，我们经常会遇到两个重要的属性："xsi:type"和"xmlns:xsi"。

java
import javax.xml.bind.JAXBContext;
import javax.xml.bind.JAXBException;
import javax.xml.bind.Marshaller;
import javax.xml.bind.annotation.XmlElement;
import javax.xml.bind.annotation.XmlRootElement;
import javax.xml.bind.annotation.XmlType;
@XmlRootElement
@XmlType(name = "person")
public class Person {
    private String name;
    private int age;
    public Person() {
    }
    public Person(String name, int age) {
        this.name = name;
        this.age = age;
    }
    @XmlElement
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    @XmlElement
    public int getAge() {
        return age;
    }
    public void setAge(int age) {
        this.age = age;
    }
    public static void main(String[] args) {
        try {
            JAXBContext context = JAXBContext.newInstance(Person.class);
            Marshaller marshaller = context.createMarshaller();
            marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);
            Person person = new Person("John", 25);
            marshaller.marshal(person, System.out);
        } catch (JAXBException e) {
            e.printStackTrace();
        }
    }
}