Java布局管理器垂直中心

尝试使用a

GridBagLayout

GridBagConstrants

public static void main(String[] args) {    Jframe frame = new Jframe();    frame.setLayout(new GridBagLayout());    JPanel panel = new JPanel();    panel.add(new JLabel("This is a label"));    panel.setBorder(new LineBorder(Color.BLACK)); // make it easy to see    frame.add(panel, new GridBagConstraints());    frame.setSize(400, 400);    frame.setLocationRelativeTo(null);    frame.setDefaultCloseOperation(Jframe.EXIT_ON_CLOSE);    frame.setVisible(true);}