java - setSize不影响按钮的大小

我有一个示例代码:

import java.awt.*;
import javax.swing.*;
import javax.swing.border.BevelBorder;

public class AWT extends JFrame {

    public static void main(String[] args) {
        final JFrame frame = new JFrame();
        frame.setPreferredSize(new Dimension(600, 450));
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setBackground(Color.green.darker());

        Button btn_1 = new Button("Button 1");
        btn_1.setBackground(Color.green.darker());
        btn_1.setSize(40, 100);
        Button btn_2 = new Button("Button 2");
        btn_2.setBackground(Color.green.darker());
        btn_2.setSize(40, 100);
        Button btn_3 = new Button("Button 3");
        btn_3.setBackground(Color.green.darker());
        btn_3.setSize(40, 100);

        JPanel players = new JPanel(new GridLayout(1, 3));
        players.add(btn_1);
        players.add(btn_2);
        players.add(btn_3);
        players.setBackground(Color.green.darker());
        players.setPreferredSize(new Dimension(450, 80));

        JPanel game = new JPanel();
        game.setBorder(BorderFactory.createBevelBorder(BevelBorder.LOWERED));
        game.setBackground(Color.green);
        game.setPreferredSize(new Dimension(600, 370));

        JPanel content = new JPanel();
        content.setLayout(new BorderLayout());
        frame.setContentPane(content);
        content.add(players, BorderLayout.NORTH);
        content.add(game, BorderLayout.SOUTH);
        frame.pack();
 frame.setVisible(true);
    }
}

结果是给了我这样一个窗口:

alt text http://img710.imageshack.us/img710/1573/21672037.gif

，虽然它会导致更像这样的事情:

alt text http://img686.imageshack.us/img686/8948/44650673.gif

为什么它不以这种方式渲染？

最佳答案

GridLayout忽略按钮的首选大小。代替

JPanel players = new JPanel(new GridLayout(1, 3));

和

JPanel players = new JPanel(); // default FlowLayout

附录:这是一个相关的示例，可以让布局和默认的首选尺寸完成工作。通过指定尽可能少的约束，当调用pack()时，外观将适应每个平台的外观。

import java.awt.*;
import javax.swing.*;
import javax.swing.border.BevelBorder;

public class AWT extends JFrame {

    public static void main(String[] args) {
        final JFrame frame = new JFrame();
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        JPanel players = new JPanel();
        players.add(new GameButton("Button 1"));
        players.add(new GameButton("Button 2"));
        players.add(new GameButton("Button 3"));
        players.setBackground(GameButton.color);

        JPanel game = new JPanel();
        game.setBorder(BorderFactory.createBevelBorder(BevelBorder.LOWERED));
        game.setBackground(Color.green);
        game.setPreferredSize(new Dimension(600, 450));

        JPanel content = new JPanel();
        content.setLayout(new BorderLayout());
        frame.setContentPane(content);
        content.add(players, BorderLayout.NORTH);
        content.add(game, BorderLayout.CENTER);
        frame.pack();
        frame.setVisible(true);
    }

    private static class GameButton extends JButton {

        private static final Color color = Color.green.darker();
        private static final Font font = new Font("SanSerif", Font.BOLD, 20);
        private String name;

        public GameButton(String name) {
            super(name);
            this.setBackground(color);
            this.setFont(font);
        }
    }
}