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我是 java 新手，我正在编写一个登录框架，在成功登录（到 mysql 数据库（使用 xampp 的本地主机））后，它会自行关闭并打开主框架。

我的登录屏幕有一个欢迎标签、一个用户名标签、一个密码标签、一个文本字段和一个密码字段以及一个登录按钮。我希望这些组件在窗口中居中并保持居中而不改变它们的大小，无论 jpanel 有多大（一旦它在屏幕上拖动它变大或变小）。

我的问题是，如果面板尺寸发生变化，我如何让它们保持居中并使其位置适应面板尺寸？假设面板大小为 100*100，按钮为 50/50，面板变为 200/200，但按钮​​保持在 50/50，如果我将其设置为可调整大小的水平或垂直，它只会变大，但我希望它保持相同的大小只需将其位置调整为 100/100。

我无法发布我的框架的图像，因为这似乎需要我没有的声誉，因为我刚刚创建了我的帐户。我希望你能想象出我想要做什么以及我现在拥有什么。

我使用 GroupLayout 的 LoginFrame 代码如下（我将 actionlistener 排除在外，因为它不相关）：

public LoginFrame() {
     setTitle("LoginFrame");
     setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
     setBounds(100, 100, 363, 270);
     contentPane = new JPanel();
     contentPane.setBackground(Color.ORANGE);
     contentPane.setBorder(new EmptyBorder(0, 0, 0, 0));
     setContentPane(contentPane);

     JLabel lblWelcome = new JLabel("Welcome");

     JLabel lblNewLabel = new JLabel("Username: ");

     textField = new JTextField();
     textField.setColumns(10);

     JLabel lblNewLabel_1 = new JLabel("Password: ");

     passwordField = new JPasswordField();

     JButton btnLogin = new JButton("Login");

        GroupLayout gl_contentPane = new GroupLayout(contentPane);
        gl_contentPane.setHorizontalGroup(
        gl_contentPane.createParallelGroup(Alignment.LEADING)
            .addGroup(gl_contentPane.createSequentialGroup()
                .addGap(107)
                .addGroup(gl_contentPane.createParallelGroup(Alignment.TRAILING)
                    .addComponent(lblNewLabel)
                    .addComponent(lblNewLabel_1))
                .addPreferredGap(ComponentPlacement.RELATED)
                .addGroup(gl_contentPane.createParallelGroup(Alignment.LEADING)
                    .addComponent(passwordField, GroupLayout.DEFAULT_SIZE, 106, Short.MAX_VALUE)
                    .addComponent(textField, GroupLayout.DEFAULT_SIZE, 104, Short.MAX_VALUE))
                .addGap(75))
            .addGroup(gl_contentPane.createSequentialGroup()
                .addGap(145)
                .addComponent(btnLogin)
                .addContainerGap(145, Short.MAX_VALUE))
            .addGroup(gl_contentPane.createSequentialGroup()
                .addGap(149)
                .addComponent(lblWelcome)
                .addContainerGap(155, Short.MAX_VALUE))
    );
    gl_contentPane.setVerticalGroup(
        gl_contentPane.createParallelGroup(Alignment.LEADING)
            .addGroup(gl_contentPane.createSequentialGroup()
                .addGap(56)
                .addComponent(lblWelcome)
                .addGap(18)
                .addGroup(gl_contentPane.createParallelGroup(Alignment.BASELINE)
                    .addComponent(textField, GroupLayout.PREFERRED_SIZE, GroupLayout.DEFAULT_SIZE, GroupLayout.PREFERRED_SIZE)
                    .addComponent(lblNewLabel))
                .addPreferredGap(ComponentPlacement.RELATED)
                .addGroup(gl_contentPane.createParallelGroup(Alignment.BASELINE)
                    .addComponent(passwordField, GroupLayout.PREFERRED_SIZE, GroupLayout.DEFAULT_SIZE, GroupLayout.PREFERRED_SIZE)
                    .addComponent(lblNewLabel_1))
                .addPreferredGap(ComponentPlacement.UNRELATED)
                .addComponent(btnLogin)
                .addContainerGap(64, Short.MAX_VALUE))
    );
    contentPane.setLayout(gl_contentPane);
 }

我希望我能得到一些有用的答案，我试图具体一点，告诉我是否有任何遗漏。谢谢

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1 回答 1

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为此，我建议您使用GridBagLayout( tutorial ) 而不是GroupLayout，因为它更简单且更灵活。它适用于GridBagConstraints（阅读有关它的参数）。

下一个代码在GridBagLayout.

public class LoginFrame extends JFrame {

private JPanel contentPane;
private JTextField textField;
private JPasswordField passwordField;

public LoginFrame() {
    setTitle("LoginFrame");
    setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    setBounds(100, 100, 363, 270);
    contentPane = new JPanel();
    contentPane.setBackground(Color.ORANGE);
    contentPane.setBorder(new EmptyBorder(0, 0, 0, 0));
    setContentPane(contentPane);

    JLabel lblWelcome = new JLabel("Welcome");

    JLabel lblNewLabel = new JLabel("Username: ");

    textField = new JTextField();
    textField.setColumns(10);

    JLabel lblNewLabel_1 = new JLabel("Password: ");

    passwordField = new JPasswordField();

    JButton btnLogin = new JButton("Login");

    contentPane.setLayout(new GridBagLayout());

    GridBagConstraints c = new GridBagConstraints();
    c.insets = new Insets(5, 5, 5, 5);

    c.gridx = 0;
    c.gridy = 0;
    c.gridwidth = 2;
    c.anchor = GridBagConstraints.CENTER;
    contentPane.add(lblWelcome, c);

    c.gridwidth = 1;
    c.gridy = 1;
    contentPane.add(lblNewLabel, c);

    c.gridx = 1;
    contentPane.add(textField, c);

    c.fill = GridBagConstraints.HORIZONTAL;
    c.gridy = 2;
    contentPane.add(passwordField, c);

    c.fill = GridBagConstraints.NONE;
    c.gridx = 0;
    contentPane.add(lblNewLabel_1, c);

    c.gridy = 3;
    c.gridwidth = 2;
    contentPane.add(btnLogin, c);
}

public static void main(String... s) {
    LoginFrame loginFrame = new LoginFrame();
    loginFrame.setVisible(true);
}
}
于 2013-11-11T07:07:52.503 回答