JAXB 编组：过滤叶元素的值

使用JAXB编组时，我们可以通过过滤叶元素的值来对XML进行更精细的控制。这对于处理大型XML文件或需要限制输出的敏感信息非常有用。在本文中，我们将介绍如何使用JAXB编组过滤叶元素的值，并提供一个案例代码来帮助理解。

java
import javax.xml.bind.annotation.*;
import javax.xml.bind.*;
import java.io.*;
@XmlRootElement
class Person {
    @XmlElement
    private String name;
    @XmlElement
    private int age;
    public Person(String name, int age) {
        this.name = name;
        this.age = age;
    }
    public Person() {
    }
    public String getName() {
        return name;
    }
    public int getAge() {
        return age;
    }
    public void setName(String name) {
        this.name = name;
    }
    public void setAge(int age) {
        this.age = age;
    }
}
public class Main {
    public static void main(String[] args) throws JAXBException, FileNotFoundException {
        Person person = new Person("John Doe", 30);
        JAXBContext context = JAXBContext.newInstance(Person.class);
        Marshaller marshaller = context.createMarshaller();
        marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);
        // 设置过滤器
        marshaller.setListener(new Marshaller.Listener() {
            @Override
            public void beforeMarshal(Object source) {
                if (source instanceof Person) {
                    Person person = (Person) source;
                    // 过滤年龄小于等于25的人
                    if (person.getAge() <= 25) {
                        person.setAge(0);
                    }
                }
            }
        });
        // 编组到文件
        marshaller.marshal(person, new FileOutputStream("person.xml"));
        // 从文件解组
        Unmarshaller unmarshaller = context.createUnmarshaller();
        Person unmarshalledPerson = (Person) unmarshaller.unmarshal(new FileInputStream("person.xml"));
        System.out.println("Name: " + unmarshalledPerson.getName());
        System.out.println("Age: " + unmarshalledPerson.getAge());
    }
}