当我们按下键盘上的TAB键时,如何使滚动窗格的滚动条可以使用光标自动移动？

Question

我有以下代码.执行下面的代码之后它显示了一个包含JInternalFrame的JFrame,它有一个JScrollPane这个JScrollPane有一个JPanel有很多输入控件.由于许多输入控件比JInternalFrame的大小更大,因此JPanel的大小因此我可滚动.

import java.awt.Dimension;
import javax.swing.JDesktopPane;
import javax.swing.JFrame;
import javax.swing.JInternalFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTextField;

public class InterfaceDesign {

    public static void main(String args[]) {
        InterfaceDesign id = new InterfaceDesign();
        id.getPnlProjectDetail("My Project");
    }

    public void getPnlProjectDetail(String strProjectName) {
        JPanel pnlPjDetail = new JPanel();
        JScrollPane scrPjDetail;
        pnlPjDetail.setLayout(null);
        pnlPjDetail.setBounds(0, 0, 400, 400);
        JFrame frmtest = new JFrame();
        JInternalFrame interFrame = new JInternalFrame();
        interFrame.setBounds(0, 0, 280, 180);

        frmtest.setBounds(1, 1, 300, 200);
        pnlPjDetail.setPreferredSize(new Dimension(400, 400));

        JLabel lblFirstName = new JLabel("First Name");
        JLabel lblLastName = new JLabel("Last Name");
        JLabel lblAddress = new JLabel("Address");
        JLabel lblCity = new JLabel("City");
        JLabel lblZipCode = new JLabel("Zip Code");
        JLabel lblPhone = new JLabel("Phone");
        JLabel lblEmailID = new JLabel("Emain Id");

        JTextField tfFirstName = new JTextField();
        JTextField tfLastName = new JTextField();
        JTextField tfAddress = new JTextField();
        JTextField tfCity = new JTextField();
        JTextField tfZipCode = new JTextField();
        JTextField tfPhone = new JTextField();
        JTextField tfEmailID = new JTextField();

        lblFirstName.setBounds(25, 55, 85, 20);
        tfFirstName.setBounds(25, 85, 85, 20);
        pnlPjDetail.add(lblFirstName);
        pnlPjDetail.add(tfFirstName);

        lblLastName.setBounds(25, 115, 85, 20);
        tfLastName.setBounds(25, 145, 85, 20);
        pnlPjDetail.add(lblLastName);
        pnlPjDetail.add(tfLastName);

        lblAddress.setBounds(25, 175, 85, 20);
        tfAddress.setBounds(25, 205, 85, 20);
        pnlPjDetail.add(lblAddress);
        pnlPjDetail.add(tfAddress);

        lblCity.setBounds(25, 235, 85, 20);
        tfCity.setBounds(25, 265, 85, 20);
        pnlPjDetail.add(lblCity);
        pnlPjDetail.add(tfCity);

        lblZipCode.setBounds(25, 295, 85, 20);
        tfZipCode.setBounds(25, 325, 85, 20);
        pnlPjDetail.add(lblZipCode);
        pnlPjDetail.add(tfZipCode);

        lblPhone.setBounds(25, 355, 85, 20);
        tfPhone.setBounds(25, 385, 85, 20);
        pnlPjDetail.add(lblPhone);
        pnlPjDetail.add(tfPhone);

        lblEmailID.setBounds(25, 415, 85, 20);
        tfEmailID.setBounds(25, 445, 85, 20);
        pnlPjDetail.add(lblEmailID);
        pnlPjDetail.add(tfEmailID);

        scrPjDetail = new JScrollPane(pnlPjDetail);

        scrPjDetail.setAutoscrolls(true);

        //frmtest.setContentPane(scrProjectDetail);
        interFrame.setContentPane(scrPjDetail);
        JDesktopPane dpane = new JDesktopPane();
        interFrame.setVisible(true);
        dpane.add(interFrame);

        //frmtest.getLayeredPane().add(interFrame);
        frmtest.setContentPane(dpane);
        //frmtest.add(scrProjectDetail);
        frmtest.setVisible(true);
        frmtest.setResizable(false);
        frmtest.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        //return pnlPjDetail;
    }
}

我需要你的指导来解决以下问题/疑虑

1. 当我们按下键盘上的TAB按钮时,光标从一个文本框移动到另一个文本框,但是当光标移动到下部输入字段时,ScrollBar(此处为垂直滚动条)不会随光标自动移动所以如何使滚动条自动移动到光标向下或向上移动？
2. 由于这是一个演示代码,是否可以在JInterNalFrame中并排添加两个JscrollPane？
3. 是否有必要使用JDesktopPane将JInternalFrame添加到JFrame中？即我们不能按如下方式添加JInternalFrame <JFrame>.getContentPane.add(<JInternalFrame>);

Answer 1

简单的任务,令人惊讶的古怪解决方案 - 就个人而言,我判断每个必须依赖焦点的应用程序代码解决方案古怪;-)

无法提供任何不依赖于焦点的东西:只需要在窗体上的每个组件上不需要focusListener,就可以稍微维护一下.相反,使用KeyboardFocusManager注册PropertyChangeListener,并在收到有关其permanentFocusOwner属性更改的通知时进行滚动

public static class FocusDrivenScroller implements PropertyChangeListener {

    private JComponent parent;

    public FocusDrivenScroller(JComponent parent) {
        this.parent = parent;
    }

    @Override
    public void propertyChange(PropertyChangeEvent evt) {
        Component focused = (Component) evt.getNewValue();
        if (focused == null || !SwingUtilities.isDescendingFrom(focused, parent)) return;
        parent.scrollRectToVisible(focused.getBounds());
    }

}

要在应用程序代码中使用,请使用驻留在JScrollPane中的表单进行实例化

public void buildAndShowDetailsFrame(String strProjectName) {
    // the container to scroll such that a focused child
    // is visible when gaining focus
    JPanel detailsForm = new JPanel();
    KeyboardFocusManager.getCurrentKeyboardFocusManager()
        .addPropertyChangeListener("permanentFocusOwner", 
                new FocusDrivenScroller(detailsForm));

    // choose and use an appropriate LayoutManager
    // note: this is only an example!
    // real-world requirements most probably need a stronger one
    detailsForm.setLayout(new BoxLayout(detailsForm, BoxLayout.PAGE_AXIS));
    // quick fill with stuff 
    String[] labels = {"First Name", "Last Name", 
            "Address", "City", "Zip Code", "Phone", "Emain Id"};
    for (String string : labels) {
        detailsForm.add(new JLabel(string));
        detailsForm.add(new JTextField());
    }
    JFrame frame = new JFrame();
    frame.add(new JScrollPane(detailsForm));
    frame.pack();
    // force scrollbar to appear
    frame.setSize(frame.getWidth(), frame.getHeight()/2);
    frame.setVisible(true);
    frame.setResizable(false);
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}

除了这些方法的第一行,它只是OP代码的缩短版本(引诱他/她使用适当的LayoutManager :-)