java - 在 Swing 中的表单验证期间绘制警告符号

Question

我开发了一个 Swing 表单，当焦点从 JTextComponent 中丢失时，它可以验证条目如果输入正确，背景将涂成绿色，否则背景将涂成红色。

这是代码:-

import java.awt.Color;
import java.awt.GridLayout;
import java.awt.event.FocusEvent;
import java.awt.event.FocusListener;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;

import javax.imageio.ImageIO;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JTextField;
import javax.swing.SwingUtilities;
import javax.swing.text.JTextComponent;



public class Form extends JFrame implements FocusListener{
JTextField fname,lname,phone,email,address;
BufferedImage img;
public static void main(String args[])
{
SwingUtilities.invokeLater(new Runnable(){public void run(){new Form();}});
}

public Form()
{
super("Form with Validation Capability");
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setSize(400,300);
setLayout(new GridLayout(5,3));

try {
    img=ImageIO.read(new File("src/warning.png"));
} catch (IOException e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
}

add(new JLabel("First Name :"));
add(fname=new JTextField(20));
add(new JLabel("Last Name :"));
add(lname=new JTextField(20));
add(new JLabel("Phone Number :"));
add(phone=new JTextField(10));
add(new JLabel("Email:"));
add(email=new JTextField(20));
add(new JLabel("Address :"));
add(address=new JTextField(20));

fname.addFocusListener(this);
lname.addFocusListener(this);
phone.addFocusListener(this);
email.addFocusListener(this);
address.addFocusListener(this);

setVisible(true);
}

public void focusGained(FocusEvent e)
{
((JTextComponent) e.getSource()).setBackground(Color.WHITE);
}
public void focusLost(FocusEvent e)
{
if(e.getSource().equals(fname))
{
    validationForText(fname);
}
else if(e.getSource().equals(lname))
{
    validationForText(lname);
}
else if(e.getSource().equals(email))
{
    validationForEmail(email);
}
else if(e.getSource().equals(phone))
{
    validationForNumber(phone);
}
else{
    ((JTextComponent) e.getSource()).setBackground(Color.GREEN);
}
}
public void validationForText(JTextComponent comp)
{
String temp=comp.getText();
if (temp.matches("^[A-Za-z]+$")) {
    comp.setBackground(Color.GREEN);
}
else
    comp.setBackground(Color.RED);
}
public void validationForNumber(JTextComponent comp)
{
String text=comp.getText();
if(text.matches("^[0-9]+$"))
    comp.setBackground(Color.GREEN);
else
    comp.setBackground(Color.RED);
}
public void validationForEmail(JTextComponent comp)
{
String text=comp.getText();
if(text.matches("[^@]+@([^.]+\\.)+[^.]+"))
    comp.setBackground(Color.GREEN);
else
    comp.setBackground(Color.RED);
}

}

这是我的简单应用程序的输出:

现在我还想在错误字段的左下角绘制一个警告符号(缓冲图像)。任何人都可以帮助我如何做到这一点，因为我不明白在哪里绘制图像。(我想使用 JLayeredPane 来完成它，因为我正在学习它的应用程序，任何代码片段都会真正有帮助)。

Answer 1

为什么不简单地添加一个带有内置 Swing 警告图标的 JLabel(使用适当的 LayoutManager 来定位它)UIManager.getIcon("OptionPane.warningIcon")

像这样:

JLabel label=new JLabel(UIManager.getIcon("OptionPane.warningIcon"));

参见here了解更多。

更新:

根据您的评论，我宁愿使用 GlassPane (并将 JLabel 添加到 glasspane)，而不是 JLayeredPane。请参阅here有关 RootPanes 的更多信息

一些建议:

• 不必要时不要扩展 JFrame

• 不要在 JFrame 上调用 setSize。使用正确的 LayoutManager 和/或在必要时重写 getPreferredSize() ，并用 pack() 替换 setSize 调用 <强>就在设置JFrame可见之前。

• 不要在类上实现 FocusListener ，除非您想与其他类共享功能。

• 还要养成使用 FocusAdapter 与 FocusListener 的习惯，这适用于一些带有附加监听器的情况，即 MouseListener 可以被替换对于MouseAdapter。这允许我们只重写我们想要的方法。在这种情况下，监听器是正确的，因为我们对两个重写的方法都做了一些操作，但正如我所说的更多关于习惯的内容

• 还始终调用重写方法的 super.XXX 实现，即 focusGained(FocusEvent fe) 除非您出于某种原因忽略它

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以下是包含上述修复的代码，包括玻璃 Pane 以在字段为红色时显示警告图标:

并在更正后将其删除:

import java.awt.Color;
import java.awt.Component;
import java.awt.Graphics2D;
import java.awt.GridLayout;
import java.awt.RenderingHints;
import java.awt.event.ComponentAdapter;
import java.awt.event.ComponentEvent;
import java.awt.event.FocusAdapter;
import java.awt.event.FocusEvent;
import java.awt.image.BufferedImage;
import java.util.HashMap;
import java.util.Map;
import javax.swing.Icon;
import javax.swing.ImageIcon;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JTextField;
import javax.swing.SwingUtilities;
import javax.swing.UIManager;
import javax.swing.text.JTextComponent;

/**
 *
 * @author David
 */
public class GlassValidationPane extends JComponent {

    private static JTextField fname, lname, phone, email, address;
    private static GlassValidationPane gvp = new GlassValidationPane();

    public static void main(String args[]) {
        SwingUtilities.invokeLater(new Runnable() {
            @Override
            public void run() {

                JFrame f = new JFrame("Form with Validation Capability");
                f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                //f.setResizable(false);
                f.setLayout(new GridLayout(5, 3));

                f.add(new JLabel("First Name :"));
                f.add(fname = new JTextField(20));
                f.add(new JLabel("Last Name :"));
                f.add(lname = new JTextField(20));
                f.add(new JLabel("Phone Number :"));
                f.add(phone = new JTextField(10));
                f.add(new JLabel("Email:"));
                f.add(email = new JTextField(20));
                f.add(new JLabel("Address :"));
                f.add(address = new JTextField(20));

                f.addComponentListener(new ComponentAdapter() {
                    @Override
                    public void componentResized(ComponentEvent ce) {
                        super.componentResized(ce);
                        gvp.refreshLocations();
                    }
                });
                FocusAdapter fl = new FocusAdapter() {
                    @Override
                    public void focusGained(FocusEvent fe) {
                        super.focusGained(fe);
                        ((JTextComponent) fe.getSource()).setBackground(Color.WHITE);
                    }

                    @Override
                    public void focusLost(FocusEvent fe) {
                        super.focusLost(fe);
                        if (fe.getSource().equals(fname)) {
                            validationForText(fname);
                        } else if (fe.getSource().equals(lname)) {
                            validationForText(lname);
                        } else if (fe.getSource().equals(email)) {
                            validationForEmail(email);
                        } else if (fe.getSource().equals(phone)) {
                            validationForNumber(phone);
                        } else {
                            gvp.removeWarningIcon(((Component) fe.getSource()));
                            ((JTextComponent) fe.getSource()).setBackground(Color.GREEN);
                        }
                    }
                };

                fname.addFocusListener(fl);
                lname.addFocusListener(fl);
                phone.addFocusListener(fl);
                email.addFocusListener(fl);
                address.addFocusListener(fl);

                f.setGlassPane(gvp);

                f.pack();
                f.setVisible(true);
                gvp.setVisible(true);
            }

            public void validationForText(JTextComponent comp) {
                String temp = comp.getText();
                if (temp.matches("^[A-Za-z]+$")) {
                    setGreen(comp);
                } else {
                    setRed(comp);
                }
            }

            public void validationForNumber(JTextComponent comp) {
                String text = comp.getText();
                if (text.matches("^[0-9]+$")) {
                    setGreen(comp);
                } else {
                    setRed(comp);
                }
            }

            public void validationForEmail(JTextComponent comp) {
                String text = comp.getText();
                if (text.matches("[^@]+@([^.]+\\.)+[^.]+")) {
                    setGreen(comp);
                } else {
                    setRed(comp);
                }
            }

            private void setRed(JTextComponent comp) {
                comp.setBackground(Color.RED);
                gvp.showWarningIcon(comp);
            }

            private void setGreen(JTextComponent comp) {
                comp.setBackground(Color.GREEN);
                gvp.removeWarningIcon(comp);

            }
        });
    }
    private HashMap<Component, JLabel> warningLabels = new HashMap<>();
    private ImageIcon warningIcon;

    public GlassValidationPane() {
        setLayout(null);//this is the exception to the rule case a layoutmanager might make setting Jlabel co-ords harder
        setOpaque(false);
        Icon icon = UIManager.getIcon("OptionPane.warningIcon");
        int imgW = icon.getIconWidth();
        int imgH = icon.getIconHeight();
        BufferedImage img = ImageUtilities.getBufferedImageOfIcon(icon, imgW, imgH);
        warningIcon = new ImageIcon(ImageUtilities.resize(img, 24, 24));
    }

    void showWarningIcon(Component c) {
        if (warningLabels.containsKey(c)) {
            return;
        }

        JLabel label = new JLabel();
        label.setIcon(warningIcon);

        //int x=c.getX();//this will make it insode the component
        int x = c.getWidth() - label.getIcon().getIconWidth();//this makes it appear outside/next to component
        int y = c.getY();

        label.setBounds(x, y, label.getIcon().getIconWidth(), label.getIcon().getIconHeight());
        add(label);
        label.setVisible(true);
        revalidate();
        repaint();
        warningLabels.put(c, label);
    }

    public void removeWarningIcon(Component c) {
        for (Map.Entry<Component, JLabel> entry : warningLabels.entrySet()) {
            Component component = entry.getKey();
            JLabel jLabel = entry.getValue();
            if (component == c) {
                remove(jLabel);
                revalidate();
                repaint();
                break;
            }
        }
        warningLabels.remove(c);
    }

    public void refreshLocations() {
        for (Map.Entry<Component, JLabel> entry : warningLabels.entrySet()) {
            Component c = entry.getKey();
            JLabel label = entry.getValue();
            //int x=c.getX();//this will make it insode the component
            int x = c.getWidth() - label.getIcon().getIconWidth();//this makes it appear outside/next to component
            int y = c.getY();

            label.setBounds(x, y, label.getIcon().getIconWidth(), label.getIcon().getIconHeight());
            revalidate();
            repaint();
        }
    }
}

class ImageUtilities {

    public static BufferedImage resize(BufferedImage image, int width, int height) {
        BufferedImage bi = new BufferedImage(width, height, BufferedImage.TRANSLUCENT);
        Graphics2D g2d = (Graphics2D) bi.createGraphics();
        g2d.addRenderingHints(new RenderingHints(RenderingHints.KEY_RENDERING, RenderingHints.VALUE_RENDER_QUALITY));
        g2d.drawImage(image, 0, 0, width, height, null);
        g2d.dispose();
        return bi;
    }

    public static BufferedImage getBufferedImageOfIcon(Icon icon, int imgW, int imgH) {
        BufferedImage img = new BufferedImage(imgW, imgH, BufferedImage.TYPE_INT_ARGB);
        Graphics2D g2d = (Graphics2D) img.getGraphics();
        g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
        icon.paintIcon(null, g2d, 0, 0);
        g2d.dispose();
        return img;
    }
}