在java中的JFrame上设置背景图像

Question

我刚开始尝试创建java接口，我想创建一个作为大学项目的一部分。

就像我说的，我是一个新手，所以我知道它可能非常简单，或者我没有把它搞砸，但如果有人能帮助它，它将会非常接近。

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.io.File;
import java.io.IOException;

import javax.imageio.*;

public class CoopWelcome extends JFrame {

    private ImageIcon image1;
    private JButton b1;
    private JTextField userName;
    private static String password = "";
    private JPanel backGround;

    CoopWelcome() {
        setLayout(new FlowLayout());
        //creating username textbox
        userName = new JTextField("");
        userName.setText("Username");
        userName.setForeground(Color.GRAY);
        userName.setColumns(10);
        getContentPane().add(userName);
        //creating password textbox
        JPasswordField passWord = new JPasswordField(10);
        passWord.setEchoChar('*');
        passWord.addActionListener(new AL());
        getContentPane().add(passWord);
        //adding the button and the label to the panel
        b1 = new JButton("something");
        getContentPane().add(b1);
        //getting the image and displaying to the label
    }

    public static void main(String[] Args) {
        //Creating the interface
        CoopWelcome gui = new CoopWelcome();
        gui.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        gui.setVisible(true);
        gui.pack();
        gui.setTitle("The Co-operative");
        try {
            gui.setContentPane(new JLabel(new ImageIcon(ImageIO.read(new File("img.jpg")))));

        } catch (IOException e) {
            System.out.println("image doesn't exist");
        }
    }

    static class AL implements ActionListener {

        public void actionPerformed(ActionEvent e) {
            JPasswordField input = (JPasswordField) e.getSource();
            char[] passy = input.getPassword();
            String p = new String(passy);
            if (p.equals(password)) {
                JOptionPane.showMessageDialog(null, "Correct");

            } else {
                JOptionPane.showMessageDialog(null, "Incorrect");
            }
        }
    }
}

Answer 1

GUI.SetContentPane（新建JLabel（新建ImageIcon（ImageIo.Read（新建文件（“img.jpg”））））；

合理的方法，但问题是，默认情况下JLabel不使用布局管理器，因此您无法轻松地向其添加组件。尝试：

JLabel background = new JLabel(...);
background.setLayout( new BorderLayout() );
gui.setContentPane( background );