BorderLayout控件大小的设置
使用BorderLayout时，中间的面板会随着窗体的变化而变化，其他区域的大小根据添加组件多少而变化。举个例子，现在想将一个面板固定到上边，高度为固定值，这是我们需要设置面板的高度。但是调用面板的
setSize()
方法根本没有效果。调用
setMaximumSize()
和
setMinimumSize()
都没有用。
最后才发现应该调用的是
setPreferredSize()才能达到效果。
请看栗子。
9 import javax.swing.JPanel;
10 import javax.swing.JTextArea;
11 import javax.swing.JTextField;
13 public class LayoutDemo {
15 public static void main(String[] args) {
16 new myFrame();
17 }
20 /**
21 * @author liuyan
22 *
23 */
24 class myFrame {
26 JFrame jframe = new JFrame("搜索");
27 JTextField textField = new JTextField(20);
28 JButton jButton = new JButton("转到");
29 JButton jButton2 = new JButton("转到2");
30 JButton jButton3 = new JButton("转到3");
31 JButton jButton4 = new JButton("转到4");
32 JTextArea textArea = new JTextArea();
33 JPanel jPanel = new JPanel(new BorderLayout(5,20));
34 JPanel jPanel2 = new JPanel(new BorderLayout());
35 JPanel jPanel3 = new JPanel(new BorderLayout());
36 JPanel jPanel4 = new JPanel(new BorderLayout());
39 /**
40 *
41 */
42 public myFrame() {
44 init();
45 }
47 /**
48 *
49 */
50 private void init()
51 {
52 jframe.setLayout(new BorderLayout());
53 jframe.add(jPanel2, BorderLayout.SOUTH);
54 jframe.add(jPanel3, BorderLayout.EAST);
55 jframe.add(jPanel4, BorderLayout.WEST);
56 jframe.add(jPanel, BorderLayout.NORTH);
58 jPanel.add(jButton, BorderLayout.EAST);
59 jPanel.add(textField, BorderLayout.CENTER);
61 jPanel2.add(jButton2);
62 jPanel3.add(jButton3);
63 jPanel4.add(jButton4);
65 jPanel.setPreferredSize(new Dimension(0, 150));
66 jPanel2.setPreferredSize(new Dimension(0, 150));
67 jPanel3.setPreferredSize(new Dimension(150, 0));
68 jPanel4.setPreferredSize(new Dimension(150, 0));
70 jframe.add(textArea, BorderLayout.CENTER);
72 jframe.setVisible(true);
73 FrameUtil.initFram(jframe, 500, 700);
74 }
77 class FrameUtil
79 public static void initFram(JFrame f, int width, int height)
80 {
81 Toolkit toolkit = Toolkit.getDefaultToolkit();
82 f.setVisible(true);
83 f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
84 Dimension d = toolkit.getScreenSize();
85 int x = (int)d.getWidth();
86 int y = (int)d.getHeight();
87 f.setBounds((x-width)/2, (y - height )/2, width, height);
88 }
9 import javax.swing.JPanel;
10 import javax.swing.JTextArea;
11 import javax.swing.JTextField;
13 public class LayoutDemo {
15 public static void main(String[] args) {
16 new myFrame();
17 }
20 /**
21 * @author liuyan
22 *
23 */
24 class myFrame {
26 JFrame jframe = new JFrame("搜索");
27 JTextField textField = new JTextField(20);
28 JButton jButton = new JButton("转到");
29 JButton jButton2 = new JButton("转到2");
30 JButton jButton3 = new JButton("转到3");
31 JButton jButton4 = new JButton("转到4");
32 JTextArea textArea = new JTextArea();
33 JPanel jPanel = new JPanel(new BorderLayout(5,20));
34 JPanel jPanel2 = new JPanel(new BorderLayout());
35 JPanel jPanel3 = new JPanel(new BorderLayout());
36 JPanel jPanel4 = new JPanel(new BorderLayout());
39 /**
40 *
41 */
42 public myFrame() {
44 init();
45 }
47 /**
48 *
49 */
50 private void init()
51 {
52 jframe.setLayout(new BorderLayout());
53 jframe.add(jPanel2, BorderLayout.SOUTH);
54 jframe.add(jPanel3, BorderLayout.EAST);
55 jframe.add(jPanel4, BorderLayout.WEST);
56 jframe.add(jPanel, BorderLayout.NORTH);
58 jPanel.add(jButton, BorderLayout.EAST);
59 jPanel.add(textField, BorderLayout.CENTER);
61 jPanel2.add(jButton2);
62 jPanel3.add(jButton3);
63 jPanel4.add(jButton4);
65 // jPanel.setPreferredSize(new Dimension(0, 150));
66 // jPanel2.setPreferredSize(new Dimension(0, 150));
67 // jPanel3.setPreferredSize(new Dimension(150, 0));
68 // jPanel4.setPreferredSize(new Dimension(150, 0));
70 jframe.add(textArea, BorderLayout.CENTER);
72 jframe.setVisible(true);
73 FrameUtil.initFram(jframe, 500, 700);
74 }
77 class FrameUtil
79 public static void initFram(JFrame f, int width, int height)
80 {
81 Toolkit toolkit = Toolkit.getDefaultToolkit();
82 f.setVisible(true);
83 f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
84 Dimension d = toolkit.getScreenSize();
85 int x = (int)d.getWidth();
86 int y = (int)d.getHeight();
87 f.setBounds((x-width)/2, (y - height )/2, width, height);
88 }
