Java JAXB教程：精确控制XML结构，将对象字段转换为XML属性

<?xml version="1.0" encoding="UTF-8"?>
<persons>
    <person
            name="Nick"
            birthday = "09.03.1814"/>
</persons>

<?xml version="1.0" encoding="UTF-8"?>
<persons>
    <person surname="Sd" name="aaa" birthday = "09.03.1814"/>
</persons>

import javax.xml.bind.annotation.XmlAccessType;
import javax.xml.bind.annotation.XmlAccessorType;
import javax.xml.bind.annotation.XmlAttribute;
import javax.xml.bind.annotation.XmlRootElement;

// @XmlRootElement(name = "person") 定义了该对象在XML中对应的根元素名为 "person"
// @XmlAccessorType(XmlAccessType.FIELD) 指示JAXB通过字段访问数据，
// 这对于将字段映射为属性至关重要。
@XmlRootElement(name = "person")
@XmlAccessorType(XmlAccessType.FIELD)
public class DtoPerson {

    // @XmlAttribute(name = "name") 将Java字段name映射为XML属性name
    @XmlAttribute(name = "name")
    private String name;

    // @XmlAttribute(name = "surname") 将Java字段surname映射为XML属性surname
    // 此字段是可选的，根据XML格式需求可有可无
    @XmlAttribute(name = "surname")
    private String surname;

    // @XmlAttribute(name = "birthday") 将Java字段birthday映射为XML属性birthday
    @XmlAttribute(name = "birthday")
    private String birthday;

    // 无参构造函数是JAXB反序列化所必需的
    public DtoPerson() {}

    // 构造函数，方便创建对象
    public DtoPerson(String name, String birthday) {
        this.name = name;
        this.birthday = birthday;
    }

    public DtoPerson(String name, String surname, String birthday) {
        this.name = name;
        this.surname = surname;
        this.birthday = birthday;
    }

    // Getters and Setters (JAXB在XmlAccessType.FIELD模式下不需要，但良好实践建议保留)
    public String getName() {
        return name;
    }

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

    public String getSurname() {
        return surname;
    }

    public void setSurname(String surname) {
        this.surname = surname;
    }

    public String getBirthday() {
        return birthday;
    }

    public void setBirthday(String birthday) {
        this.birthday = birthday;
    }

    @Override
    public String toString() {
        return "DtoPerson{" +
               "name='" + name + '\'' +
               ", surname='" + surname + '\'' +
               ", birthday='" + birthday + '\'' +
               '}';
    }
}

import javax.xml.bind.annotation.XmlAccessType;
import javax.xml.bind.annotation.XmlAccessorType;
import javax.xml.bind.annotation.XmlElement;
import javax.xml.bind.annotation.XmlRootElement;
import java.util.List;

// @XmlRootElement(name = "persons") 定义了该对象在XML中对应的根元素名为 "persons"
@XmlRootElement(name = "persons")
@XmlAccessorType(XmlAccessType.FIELD) // 同样通过字段访问
public class PersonsWrapper {

    // @XmlElement(name = "person") 指示列表中每个元素都应被编组为名为 "person" 的XML子元素
    @XmlElement(name = "person")
    private List<DtoPerson> personList;

    // 无参构造函数是JAXB反序列化所必需的
    public PersonsWrapper() {}

    public PersonsWrapper(List<DtoPerson> personList) {
        this.personList = personList;
    }

    public List<DtoPerson> getPersonList() {
        return personList;
    }

    public void setPersonList(List<DtoPerson> personList) {
        this.personList = personList;
    }
}

import javax.xml.bind.JAXBContext;
import javax.xml.bind.JAXBException;
import javax.xml.bind.Marshaller;
import java.io.File;
import java.util.ArrayList;
import java.util.List;

public class XmlGenerator {

    /**
     * 根据提供的DtoPerson列表生成XML文件。
     *
     * @param persons 要编组的DtoPerson对象列表
     * @param outputPath 生成XML文件的路径
     */
    public static void createXmlFromPersons(List<DtoPerson> persons, String outputPath) {
        try {
            // 1. 创建PersonsWrapper对象，将DtoPerson列表包装起来
            PersonsWrapper personsWrapper = new PersonsWrapper(persons);

            // 2. 创建JAXBContext实例。JAXBContext需要知道要编组的根元素类。
            // 这里是PersonsWrapper.class，因为它将作为XML的根。
            JAXBContext jaxbContext = JAXBContext.newInstance(PersonsWrapper.class);

            // 3. 创建Marshaller对象，用于将Java对象转换为XML
            Marshaller marshaller = jaxbContext.createMarshaller();

            // 4. 设置Marshaller属性，使其生成格式化（美观）的XML输出
            marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);

            // 5. 将PersonsWrapper对象编组到文件
            File file = new File(outputPath);
            marshaller.marshal(personsWrapper, file);

            System.out.println("XML文件已成功创建于: " + file.getAbsolutePath());

        } catch (JAXBException e) {
            System.err.println("创建XML文件时发生错误: " + e.getMessage());
            e.printStackTrace();
            throw new RuntimeException("XML生成失败", e);
        }
    }

    public static void main(String[] args) {
        // 示例用法
        List<DtoPerson> personList = new ArrayList<>();

        // 添加第一个示例人员 (只有name和birthday)
        personList.add(new DtoPerson("Nick", "09.03.1814"));

        // 添加第二个示例人员 (包含surname, name和birthday)
        personList.add(new DtoPerson("John", "Doe", "15.07.1990"));

        // 添加更多人员
        personList.add(new DtoPerson("Jane", "Smith", "22.11.1985"));

        // 调用方法生成XML文件
        createXmlFromPersons(personList, "persons_output.xml");
    }
}

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<persons>
    <person name="Nick" birthday="09.03.1814"/>
    <person name="John" surname="Doe" birthday="15.07.1990"/>
    <person name="Jane" surname="Smith" birthday="22.11.1985"/>
</persons>