帮忙看下，JPanel里面插背景为什么不显示出来

Question

public class LoginPanel extends JPanel { // 登陆界面

         Image backGround1 = Toolkit.getDefaultToolkit().getImage("./src/1615465.jpg");

          public LoginPanel() {
                   super(true);
                   this.setLayout(new BorderLayout());
     .....................
     .....................
     .....................         @Override
         public void paintComponent(Graphics g) {
                  super.paintComponent(g);
                  Dimension size = this.getParent().getSize();
                  g.drawImage(backGround1, 0, 0, size.width, size.height, null);
         }
}public class Test {         public static void main(String[] args) {
                  JFrame frame = new JFrame("登陆");
                  frame.setDefaultCloseOperation(3);
                  frame.setSize(640, 480);
                  Dimension displaySize = Toolkit.getDefaultToolkit().getScreenSize(); // 获得屏幕尺寸
                  Dimension frameSize = frame.getSize(); // dialog尺寸
                  frame.setLocation((displaySize.width - frameSize.width) / 2,
                                     (displaySize.height - frameSize.height) / 2); // 设置位置，屏幕中央                  frame.add(new LoginPanel());
                  frame.setVisible(true);
}
}

Answer 1

把你那Override方法改一改public void paintComponent(Graphics g) { 
Graphics2D g2 = (Graphics2D) g;
super.paintComponent(g);
Image img = Toolkit.getDefaultToolkit().getImage(backGround1);
g2.drawImage(img, 0, 0, this.getWidth(), this.getHeight(), this);
}