将数据从 XML 返回到 UI

Question

我有一些循环通过 XML 文件的代码，并获取 <savedPositions> 的每个实例。我正在尝试将每个数据中的数据添加到一个数组中，以便我可以返回它并在我的 UI 中使用字符串 - 我不确定如何通过显示 <savedPositions> 的每个实例将数据读回我的应用程序中在每个按钮点击。这意味着我的文本框中只显示了一个<savedPositions> 实例。

我将如何做到这一点，以便在每个按钮单击时，文本框都会更新为下一个 <savedPositions> 信息？ - 谢谢

我的 XML：

<savedPositions>
  <savedPosition>
    <nBehaviour>nBehaviour1</nBehaviour>
    <aBehaviour>aBehaviour1</aBehaviour>
    <findings>findings1</findings>
    <forces>forces1</forces>
    <gap>gap1</gap>
    <position1>0.6488889</position1>
    <position2>-1000.0</position2>
  </savedPosition>
  <savedPosition>
    <nBehaviour>nBehaviour2</nBehaviour>
    <aBehaviour>aBehaviour2</aBehaviour>
    <findings>findings2</findings>
    <forces>aBehaviour2</forces>
    <gap>gap2</gap>
    <position1>-1000.0</position1>
    <position2>-1000.0</position2>
  </savedPosition>
</savedPositions>

阅读 XML 代码：

public class XmlToObject {

    public static ArrayList<ArrayList<String>> main() {

        ArrayList<ArrayList<String>> obj1 = new ArrayList<ArrayList<String>>();
        ArrayList<ArrayList<String>> obj = new ArrayList<ArrayList<String>>();

        try {
            DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
            DocumentBuilder db = dbf.newDocumentBuilder();
            Document d = db.parse("/home/nicolas/savedPos.xml");
            XPath xp = XPathFactory.newInstance().newXPath();
            NodeList nl = (NodeList) xp.compile("//savedPosition").evaluate(d, XPathConstants.NODESET);
            System.out.println("number of saved positions " + nl.getLength());

            for (int i = 0; i < nl.getLength(); i++) {

                String a = (xp.compile("./nBehaviour").evaluate(nl.item(i)));
                String b = (xp.compile("./aBehaviour").evaluate(nl.item(i)));
                String c = (xp.compile("./gap").evaluate(nl.item(i)));
                String d1 = (xp.compile("./forces").evaluate(nl.item(i)));
                String e = (xp.compile("./findings").evaluate(nl.item(i)));
                String f = (xp.compile("./position1").evaluate(nl.item(i)));
                String g = (xp.compile("./position2").evaluate(nl.item(i)));

                ArrayList<String> savedPosition = new ArrayList<String>();
                savedPosition.add(a);
                savedPosition.add(b);
                savedPosition.add(c);
                savedPosition.add(d1);
                savedPosition.add(e);
                savedPosition.add(f);
                savedPosition.add(g);

                obj.add(savedPosition);

            }

            return obj;

        } catch (Exception l) {
            System.out.println(l.getMessage());
        }

        return obj1;
    }
}

单击按钮时调用 XML：

load.addActionListener(new ActionListener() {
    @Override
    public void actionPerformed(ActionEvent e) {

        ArrayList<ArrayList<String>> obj = XmlToObject.main();

        for(ArrayList<String> r: obj){
            for(int i = 0; i < r.size(); i++){
                System.out.println(r.get(i) + "");
            }
            textArea.setText(r.get(0));
            textArea1.setText(r.get(1));
            textArea2.setText(r.get(2));
            textArea3.setText(r.get(3));
            textArea4.setText(r.get(4));
            mediaPlayerComponent.getMediaPlayer().setPosition(Float.parseFloat(r.get(5)));
            mediaPlayerComponent2.getMediaPlayer().setPosition(Float.parseFloat(r.get(6)));
        }
    }
});

Answer 1

只解析一次你的 XML 文件，并声明一个整数来跟踪当前显示的位置

    List<List<String>> obj = XmlToObject.main();
    int displayedPositionIndex = 0;

然后在你的 ActionListener 上，增加你的计数器并显示下一个位置

load.addActionListener(new ActionListener() {
    @Override
    public void actionPerformed(ActionEvent e) {
        displayedPositionIndex++;
        if(displayedPositionIndex >= obj.size()) {
            displayedPositionIndex = 0; // to loop back to first after last position
        }
        setPosition(displayedPositionIndex);
    }
});

我用这个实用方法让事情更清楚

private void setPosition(int index) {
    List<String> positionData = obj.get(index);
    textArea.setText(positionData.get(0));
    textArea1.setText(positionData.get(1));
    textArea2.setText(positionData.get(2));
    textArea3.setText(positionData.get(3));
    textArea4.setText(positionData.get(4));
    mediaPlayerComponent.getMediaPlayer().setPosition(Float.parseFloat(positionData.get(5)));
    mediaPlayerComponent2.getMediaPlayer().setPosition(Float.parseFloat(positionData.get(6)));
}

注意

在您的 XmlToObject 中，使用List<List<String>> 比使用ArrayList<ArrayList<String>> 更好（尽可能使用接口）：

class XmlToObject {

    public static List<List<String>> main() {
        List<List<String>> positions = new ArrayList<>();

        try {
            DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
            DocumentBuilder db = dbf.newDocumentBuilder();
            Document d = db.parse("/path/to/savedPos.xml");
            XPath xp = XPathFactory.newInstance().newXPath();

            NodeList nl = (NodeList) xp.compile("//savedPosition").evaluate(d, XPathConstants.NODESET);
            System.out.println("number of saved positions " + nl.getLength());

            for (int i = 0; i < nl.getLength(); i++) {
                String a = (xp.compile("./nBehaviour").evaluate(nl.item(i)));
                String b = (xp.compile("./aBehaviour").evaluate(nl.item(i)));
                String c = (xp.compile("./gap").evaluate(nl.item(i)));
                String d1 = (xp.compile("./forces").evaluate(nl.item(i)));
                String e = (xp.compile("./findings").evaluate(nl.item(i)));
                String f = (xp.compile("./position1").evaluate(nl.item(i)));
                String g = (xp.compile("./position2").evaluate(nl.item(i)));

                List<String> savedPosition = Arrays.asList(a, b, c, d1, e, f, g);
                positions.add(savedPosition);
            }

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

        return positions;
    }
}