java - 无法使用 JAXB 读取 XML 文件

Question

我正在尝试读取下面的 XML 文件:

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<parts>
    <item>CPU</item>
    <item>GPU</item>
    <item>PSU</item>
</parts>

我的目标是将项目添加到 DefaultDataModel，以便我可以更新 JList。但是，当我进入 for every 循环时，列表​​中没有添加任何内容，控制台也没有打印任何内容。有人可以告诉我我是否做错了什么吗？

public void load()
{
    // First clear the JLit before loading anything
    partList.clear();
    chosenList.clear();

    File file = new File("partsList.xml");

    try
    {
        // Setup JAXB to create a list of strings from the XML file
        JAXBContext context = JAXBContext.newInstance(Parts.class);
        Unmarshaller unmarshaller = context.createUnmarshaller();

        // Read the XML file
        List<String> parts = (List<String>) unmarshaller.unmarshal(file);
        System.out.println(parts);

        for (String item : parts)
        {
            chosenList.addElement(item);
            System.out.println(item);
        }

        list_1.setModel(chosenList);
        list_1.repaint();
    }

    catch (JAXBException e)
    {
        e.printStackTrace();            
    }       
}

Parts.java

@XmlRootElement
public class Parts extends AbstractList<String>
{
    /* This allows me to have a single instantiation of this class for
     * adding the PC components before writing them to the XML file
     */

    @XmlElement(name="item")
    private List<String> list = new ArrayList<String>();

    @Override
    public boolean add(String element)
    {
        return list.add(element);
    }

    @Override
    public String get(int arg0) {
        // TODO Auto-generated method stub
        return null;
    }

    @Override
    public int size() {
        // TODO Auto-generated method stub
        return 0;
    }
}

Answer 1

首先，您的 Parts 类不完整。应实现 get 和 size 方法。

@Override
public String get(int arg0) {
    return list.get(arg0);
}

@Override
public int size() {
    return list.size();
}

然后，解码会为您提供一个 Parts 对象，而不是字符串列表。所以，应该是:

Parts parts = (Parts) unmarshaller.unmarshal(file);
System.out.println(parts);

for (int i = 0; i < parts.size(); i++) {
    chosenList.addElement(parts.get(i));
    System.out.println(parts.get(i));
}