你的GridBagLayout尝试图片表明你要么没有在添加组件时使用GridBagConstraints,要么使用了不正确的方式。
如果您想将文本组件居中放置在GUI上,并将它们放置在自己的框中,则应该为包含它们的容器使用GridBagLayout,并传递适当的GridBagConstraints,以便与您的需求良好配合。这意味着为约束条件提供适当的gridx和gridy值以匹配您希望放置组件的网格位置。此外,您还需要正确地锚定组件,并通常要设置约束条件插入以在组件周围留出空白空间缓冲区,以避免它们相互挤在一起。我个人在做这样的事情时,经常使用一个4 x 4网格,其中包括两行两列,左侧有JLabel的一列,以便用户知道右侧每个文本组件表示什么。我经常使用辅助方法来帮助创建我的约束条件,类似于以下内容:
private GridBagConstraints createGbc(int x, int y) {
GridBagConstraints gbc = new GridBagConstraints();
gbc.gridx = x;
gbc.gridy = y;
gbc.fill = GridBagConstraints.HORIZONTAL;
gbc.weightx = 1.0;
gbc.weighty = 0.0;
gbc.insets = new Insets(I_GAP, I_GAP, I_GAP, I_GAP);
gbc.anchor = x % 2 == 0 ? GridBagConstraints.WEST : GridBagConstraints.EAST;
return gbc;
}
然后我会像这样使用它:
JPanel innerPanel = new JPanel(new GridBagLayout());
JLabel userNameLabel = new JLabel("User Name:");
userNameLabel.setForeground(Color.LIGHT_GRAY);
innerPanel.add(userNameLabel, createGbc(0, 0));
innerPanel.add(tfUsername, createGbc(1, 0));
JLabel passwordLabel = new JLabel("Password:");
passwordLabel.setForeground(Color.LIGHT_GRAY);
innerPanel.add(passwordLabel, createGbc(0, 1));
innerPanel.add(tfPassword, createGbc(1, 1));
一个工作示例可能如下所示:
![在此输入图像描述](https://istack.dev59.com/pXztj.webp)
请注意,该示例仅供参考。
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.Insets;
import java.awt.Window;
import java.awt.Dialog.ModalityType;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.net.URL;
import javax.imageio.ImageIO;
import javax.swing.*;
import javax.swing.border.Border;
@SuppressWarnings("serial")
public class MetaSpaceLauncherPanel extends JPanel {
public static final String IMG_PATH = "https://upload.wikimedia.org/wikipedia/"
+ "commons/thumb/b/be/Milky_Way_at_Concordia_Camp%2C_Karakoram_Range%2"
+ "C_Pakistan.jpg/1280px-Milky_Way_at_Concordia_Camp%2C_Karakoram_Range"
+ "%2C_Pakistan.jpg";
private static final int I_GAP = 10;
private static final int COLS = 15;
private JTextField tfUsername = new JTextField(COLS);
private JPasswordField tfPassword = new JPasswordField(COLS);
private BufferedImage background = null;
public MetaSpaceLauncherPanel(BufferedImage background) {
this.background = background;
ActionListener listener = e -> {
String userName = tfUsername.getText().trim();
char[] password = tfPassword.getPassword();
Window window = SwingUtilities.getWindowAncestor(MetaSpaceLauncherPanel.this);
if (userName.isEmpty() || password.length == 0) {
String message = "Both user name and password fields must contain data";
String title = "Invalid Data Entry";
JOptionPane.showMessageDialog(window, message, title, JOptionPane.ERROR_MESSAGE);
} else {
window.dispose();
}
};
tfUsername.addActionListener(listener);
tfPassword.addActionListener(listener);
JPanel innerPanel = new JPanel(new GridBagLayout());
innerPanel.setOpaque(false);
Border outerBorder = BorderFactory.createEtchedBorder();
Border innerBorder = BorderFactory.createEmptyBorder(I_GAP, I_GAP, I_GAP, I_GAP);
Border border = BorderFactory.createCompoundBorder(outerBorder, innerBorder);
innerPanel.setBorder(border);
JLabel userNameLabel = new JLabel("User Name:");
userNameLabel.setForeground(Color.LIGHT_GRAY);
innerPanel.add(userNameLabel, createGbc(0, 0));
innerPanel.add(tfUsername, createGbc(1, 0));
JLabel passwordLabel = new JLabel("Password:");
passwordLabel.setForeground(Color.LIGHT_GRAY);
innerPanel.add(passwordLabel, createGbc(0, 1));
innerPanel.add(tfPassword, createGbc(1, 1));
setLayout(new GridBagLayout());
add(innerPanel);
}
public String getUserName() {
return tfUsername.getText();
}
public char[] getPassword() {
return tfPassword.getPassword();
}
private GridBagConstraints createGbc(int x, int y) {
GridBagConstraints gbc = new GridBagConstraints();
gbc.gridx = x;
gbc.gridy = y;
gbc.fill = GridBagConstraints.HORIZONTAL;
gbc.weightx = 1.0;
gbc.weighty = 0.0;
gbc.insets = new Insets(I_GAP, I_GAP, I_GAP, I_GAP);
gbc.anchor = x % 2 == 0 ? GridBagConstraints.WEST : GridBagConstraints.EAST;
return gbc;
}
@Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
if (background != null) {
g.drawImage(background, 0, 0, this);
}
}
@Override
public Dimension getPreferredSize() {
if (isPreferredSizeSet() || background == null) {
return super.getPreferredSize();
}
int w = background.getWidth();
int h = background.getHeight();
return new Dimension(w, h);
}
private static void createAndShowGui() {
BufferedImage img = null;
try {
URL imgUrl = new URL(IMG_PATH);
img = ImageIO.read(imgUrl);
} catch (IOException e) {
e.printStackTrace();
System.exit(-1);
}
MetaSpaceLauncherPanel launcherPanel = new MetaSpaceLauncherPanel(img);
JDialog dialog = new JDialog(null, "MetaSpace Launcher", ModalityType.APPLICATION_MODAL);
dialog.setDefaultCloseOperation(JDialog.DISPOSE_ON_CLOSE);
dialog.getContentPane().add(launcherPanel);
dialog.pack();
dialog.setLocationRelativeTo(null);
dialog.setVisible(true);
String userName = launcherPanel.getUserName();
char[] password = launcherPanel.getPassword();
String message = String.format("<html>User Name: %s<br/>Password: %s</html>", userName,
new String(password));
JOptionPane.showMessageDialog(null, message);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(() -> createAndShowGui());
}
}
null
布局的唯一“正确”方法是不要使用它们。