背景图像隐藏所有GUI设计组件 [英] Background image hides all GUI design components

问题描述

我正在使用GUI应用程序，我使用swing组件来设计GUI。我想为我的表单设置背景图像，但是当我设置图像时，它会重叠所有用于设计GUI的组件。

I am working on GUI application where i have used swing components to design GUI. I want to set background image for my form but when i set image it overlaps all components used to design GUI.

首先我没有背景图像的表单如下所示，

First my form without background image is as below shown,

我的代码是，

public class Login extends JFrame{
    public static JFrame myFrame;
    public LoginPanel loginPanel;

    public Login() throws IOException
    {
        initilize();
    }

    public void initilize()throws IOException {

        myFrame = new JFrame("Message"){ 
            private Image backgroundImage = ImageIO.read(new File("D:/Sky.jpg"));
            public void paint( Graphics g ) { 
                super.paint(g);
                g.drawImage(backgroundImage, 0, 0, null);
            }
        };
        myFrame.setLayout(new BorderLayout());

        loginPanel = new LoginPanel();

        //Panel
        Container c = myFrame.getContentPane();

        c.add(loginPanel, BorderLayout.WEST);
        myFrame.setSize(300, 150);
        myFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        myFrame.setVisible(true);
        myFrame.setLocationRelativeTo(null);

    } 

    public static void main(String[] arg) {
        SwingUtilities.invokeLater(new Runnable()
        {
            public void run()
            {
                try {
                    new Login();
                } catch (IOException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }
            }
        });
    }
}

LoginPanel.java

LoginPanel.java

public class LoginPanel extends JPanel implements ActionListener {
    public JLabel user_no=null;
    public JLabel password=null;
    public JButton btn_login = null;
    public JButton btn_newUser = null;
    public JTextField usernameField=null;
    public JPasswordField passwordField=null;
    public static String userNo;
    public ArrayList msgList = new ArrayList();

    public LoginPanel()
    {
        initilize();
        initConnection();
    }

    private void initilize() {

        Dimension size = getPreferredSize();
        size.width = 285;
        size.height = 150;
        setPreferredSize(size);

        setBorder(BorderFactory.createTitledBorder(null, "Login Details", TitledBorder.CENTER, TitledBorder.TOP));

        user_no = new JLabel("User No : ");

        password = new JLabel("Password : ");

        usernameField = new JTextField(14);

        passwordField = new JPasswordField(14);

        btn_login = new JButton("Login");

        btn_newUser = new JButton("New User");

        setLayout(new GridBagLayout());

        GridBagConstraints gc = new GridBagConstraints();

        //// First column /////////////////////////

        gc.anchor = GridBagConstraints.LINE_START;

        gc.gridx = 0;
        gc.gridy = 0;
        add(user_no, gc);

        gc.gridx = 0;
        gc.gridy = 1;
        add(password, gc);

        //// Second column
        gc.anchor = GridBagConstraints.LINE_START;

        gc.gridx = 1;
        gc.gridy = 0;
        add(usernameField, gc);

        gc.gridx = 1;
        gc.gridy = 1;
        add(passwordField, gc);

        // Final row
        gc.anchor = GridBagConstraints.FIRST_LINE_START;
        gc.gridx = 1;
        gc.gridy = 2;
        add(btn_login, gc);

        gc.anchor = GridBagConstraints.FIRST_LINE_END;
        gc.gridx = 1;
        gc.gridy = 2;
        add(btn_newUser, gc);

    }

    private void initConnection() {
        btn_login.addActionListener(this);
        btn_newUser.addActionListener(this);
    }

    @Override
    public void actionPerformed(ActionEvent e) {

        if(e.getSource().equals(btn_login))
        {
            userNo = usernameField.getText();
            String userPwd = passwordField.getText();
            System.out.println(userNo+" "+userPwd);
            Connection con = ConnectionImpl.getConnection();

            try
            {
                PreparedStatement pstmt;

                String sql = "SELECT sender_no,pwd FROM tb_login where sender_no ='"+userNo+"'"; 

                pstmt= con.prepareStatement(sql);

                ResultSet rs = pstmt.executeQuery();

                if(rs.next())
                {
                    if(userNo.equalsIgnoreCase(rs.getString(1))&&userPwd.equalsIgnoreCase(rs.getString(2)))
                    {
                        System.out.println("Successfull login");

                        String sql2 = "Select msg from tb_msg where sender_no='"+userNo+"'";

                        pstmt= con.prepareStatement(sql2);

                        ResultSet rs2 = pstmt.executeQuery();

                        while(rs2.next())
                        {
                            msgList.add(rs2.getString(1));
                        }
                        System.out.println("msgList = "+msgList.size());

                        Login.myFrame.dispose();
                        new AddMessage(userNo,msgList);
                    }
                }
            }
            catch (Exception exp) {
                exp.printStackTrace();
            }
        }

        if(e.getSource().equals(btn_newUser))
        {
            Login.myFrame.dispose();
            new NewUser();
        }
    }

}

设定后背景图片看起来像这样，

After setting background image it look like this,

隐藏 JButton 的组件， JLabel 。

推荐答案

1. 画图像到 LoginPanel（JPanel）而不是 ContentPane （不好直接绘制到 JFrame ）

1. paint Image to the LoginPanel (JPanel) instead of ContentPane (not good idead to paint directly to the JFrame)

JPanel 使用 paintComponent（）而不是 paint（对于JFrame ）

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