jaxb多态解析

父类Student.class

import javax.xml.bind.annotation.XmlSeeAlso;
//使用@XmlSeeAlso注解： 您需要在父类上使用@XmlSeeAlso注解，
//将所有可能的子类添加到注解中，以告知JAXB在处理对象时考虑这些子类。
@XmlSeeAlso({Student1.class,Student2.class})
public class Student {
}

子类Student1.class

import javax.xml.bind.annotation.XmlElement;
import javax.xml.bind.annotation.XmlRootElement;

@XmlRootElement(name = "Student")//从父类进行xml解析时,名字设定
public class Student1 extends Student{

    private String name;

    public Student1() {
    }

    @XmlElement(name = "Name")
    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }
}

子类Student2.class

import javax.xml.bind.annotation.XmlElement;
import javax.xml.bind.annotation.XmlRootElement;

@XmlRootElement(name = "Student")
public class Student2 extends Student{
    private String name;
    public Student2() {
    }
    @XmlElement(name = "Name")
    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }
}

Person类

import javax.xml.bind.annotation.XmlElement;
import javax.xml.bind.annotation.XmlElementRef;
import javax.xml.bind.annotation.XmlRootElement;

@XmlRootElement(name = "Person")
public class Person {
    private String id;
    private Student student;
    public Person() {
    }
    @XmlElement(name = "Id")
    public String getId() {
        return id;
    }

    public void setId(String id) {
        this.id = id;
    }
//在JAXB中，如果你有一个包含多个不同子类实例的集合，并且希望能够正确地将这些子类实例反序列化回对象，
//并且在序列化时能够正确地指定实际子类的元素名称，就可以使用@XmlElementRef。

//这个注解通常与@XmlSeeAlso注解一起使用，后者用于指定在多态性情况下JAXB需要处理的可能的子类。
    @XmlElementRef
    public Student getStudent() {
        return student;
    }

    public void setStudent(Student student) {
        this.student = student;
    }
}

测试用例

    @Test
    public void jaxb(){
        Person person = new Person();
        person.setId("001");
        Student1 s1 = new Student1();
        s1.setName("zs");
        person.setStudent1(s1);
        Student1 s2 = new Student1();
        s2.setName("ls");
        person.setStudent2(s2);
        JAXBContext context;
        try {
            context = JAXBContext.newInstance(Person.class);
            Marshaller marshaller = context.createMarshaller();
            marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);
            marshaller.marshal(person, System.out);
        } catch (JAXBException e) {
            System.out.println(e);
            e.printStackTrace();
        }
    }

结果

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<Person>
    <Id>001</Id>
    <Student>
        <Name>zs</Name>
    </Student>
    <Student>
        <Name>ls</Name>
    </Student>
</Person>