java - 将页面右上角的组件与 GridBagLayout Manager 对齐

Question

我正在尝试制作一个像 facebook 一样的登录页面，但我编写的代码没有在左上角显示它，而是在页面中央显示，我正在使用 GridBagLayout 和 anchore 将文本设置为FIRST_LINE_END。

final JFrame f2=new JFrame("Admin Main");
                    f2.setSize(1350,730);
                    f2.setVisible(true);
                    f1.setVisible(false);
                    f2.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);![enter image description here][2]
                    GridBagLayout gbl=new GridBagLayout();
                    final JPanel p2=new JPanel(gbl){
        private Image img = ImageIO.read(new File("F:\\Untitled Folder\\Rohan\\football2.jpg"));
        @Override
                          protected void paintComponent( Graphics g ) { 
              super.paintComponent(g);

              g.drawImage(img, 0,0,1366,730, null);
              }
       };;
                    GridBagConstraints g2=new GridBagConstraints();
                    g2.insets=new Insets(3,3,3,3);
                    JLabel l2=new JLabel("Admin ID",JLabel.LEFT);
                    JLabel l3=new JLabel("Password",JLabel.LEFT);
                    l2.setFont(new Font("TimesRoman",Font.BOLD,16));
                    l2.setForeground(Color.BLUE);
                    l2.setBackground(Color.WHITE);
                    l3.setFont(new Font("TimesRoman",Font.BOLD,16));
                    l3.setForeground(Color.BLUE);
                    l3.setBackground(Color.WHITE);
                    final JTextField t1=new JTextField(15);
                    final JPasswordField pw1=new JPasswordField(15);
                    JButton b3=new JButton("Back");
                    JButton b4=new JButton("Sign in");
                    f2.add(p2);
                    g2.anchor=GridBagConstraints.FIRST_LINE_END;
                    g2.gridx=1;
                    g2.gridy=1;
                    p2.add(l2,g2);
                    g2.gridx=2;
                    g2.gridy=1;
                    p2.add(t1,g2);
                    g2.gridx=1;
                    g2.gridy=2;
                    p2.add(l3,g2);
                    g2.gridx=2;
                    g2.gridy=2;
                    p2.add(pw1,g2);
                    g2.gridx=1;
                    g2.gridy=3;
                    p2.add(b3,g2);
                    g2.gridx=2;
                    g2.gridy=3;
                    p2.add(b4,g2);

Answer 1

我发现您当前的布局存在两个问题:

1. 您将登录面板放在父级 BorderLayout 的中心(这样您的面板就会拉伸(stretch)到其容器的大小)
2. GridBagLayout 中没有任何东西可以将您的组件“推”到顶部和左侧。

这里有几个选项:

1. 您将登录面板嵌套到多个面板中(例如使用 BorderLayout，一次使用约束 NORTH，第二次使用约束 WEST)。
2. 将您的 loginPanel 添加到 WEST，并将“填充”组件添加到 GridBagLayout 的底部，以便将其他组件推到顶部。

这是第二种解决方案的演示:

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.FlowLayout;
import java.awt.Font;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.Insets;
import java.net.MalformedURLException;
import java.net.URL;

import javax.swing.Box;
import javax.swing.ImageIcon;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JPasswordField;
import javax.swing.JTextField;
import javax.swing.SwingUtilities;

public class TestLoginGridBagLayout {

    protected void initUI() throws MalformedURLException {
        JFrame frame = new JFrame("Admin Main");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        JLabel background = new JLabel(new ImageIcon(new URL(
                "http://media1.santabanta.com/full1/Football/Football%20Abstract/football-abstract-6a.jpg"))) {
            @Override
            public Dimension getPreferredSize() {
                Dimension preferredSize = super.getPreferredSize();
                Dimension layoutPreferredSize = super.preferredSize();
                preferredSize.width = Math.max(preferredSize.width, layoutPreferredSize.width);
                preferredSize.height = Math.max(preferredSize.height, layoutPreferredSize.height);
                return preferredSize;
            }
        };
        background.setLayout(new BorderLayout());
        frame.add(background);
        GridBagLayout gbl = new GridBagLayout();
        final JPanel loginPanel = new JPanel(gbl);
        loginPanel.setOpaque(false);
        background.add(loginPanel, BorderLayout.WEST);
        JLabel adminIDLabel = new JLabel("Admin ID", JLabel.LEFT);
        JLabel passwordLabel = new JLabel("Password", JLabel.LEFT);
        adminIDLabel.setFont(new Font("TimesRoman", Font.BOLD, 16));
        adminIDLabel.setForeground(Color.BLUE);
        adminIDLabel.setBackground(Color.WHITE);
        passwordLabel.setFont(new Font("TimesRoman", Font.BOLD, 16));
        passwordLabel.setForeground(Color.BLUE);
        passwordLabel.setBackground(Color.WHITE);
        final JTextField adminID = new JTextField(15);
        final JPasswordField password = new JPasswordField(15);
        JPanel buttonPanel = new JPanel(new FlowLayout(FlowLayout.TRAILING));
        buttonPanel.setOpaque(false);
        JButton back = new JButton("Back");
        JButton signIn = new JButton("Sign in");
        buttonPanel.add(back);
        buttonPanel.add(signIn);
        GridBagConstraints gbc = new GridBagConstraints();
        gbc.insets = new Insets(3, 3, 3, 3);
        gbc.anchor = GridBagConstraints.FIRST_LINE_END;
        loginPanel.add(adminIDLabel, gbc);
        gbc.gridwidth = GridBagConstraints.REMAINDER;
        loginPanel.add(adminID, gbc);
        gbc.gridwidth = 1;
        loginPanel.add(passwordLabel, gbc);
        gbc.gridwidth = GridBagConstraints.REMAINDER;
        loginPanel.add(password, gbc);
        loginPanel.add(buttonPanel, gbc);
        GridBagConstraints gbcFiller = new GridBagConstraints();
        gbcFiller.weightx = 1.0;
        gbcFiller.weighty = 1.0;
        gbcFiller.fill = GridBagConstraints.BOTH;
        loginPanel.add(Box.createGlue(), gbcFiller);
        frame.pack();
        frame.setVisible(true);
    }

    /**
     * @param args
     */
    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {
            @Override
            public void run() {
                try {
                    new TestLoginGridBagLayout().initUI();
                } catch (MalformedURLException e) {
                    e.printStackTrace();
                }
            }
        });
    }

}

我还冒昧地:

• 将您的变量重命名为有意义的名称(它使您的代码更易于他人阅读)
• 用 JLabel 替换您的自定义背景图像面板
• 使用另一个 LayoutManager 将按钮移动到嵌套面板
• 再拍一张背景图片，因为我没有你的。