java - 在 JFrame 上绘制图像的最简单方法？

Question

这个问题已经有答案了:

How to show pictures in jFrame, using java2d? (3 个回答)

已关闭 7 年前。

我是java初学者。我有一个名为 1.png 的图像。我试图将它显示在我的 JFrame 上，但是当我运行代码时，框架运行但没有图像。这是我的代码:

package practice;

import java.awt.*;
import java.awt.image.*;
import java.io.*;
import javax.imageio.*;
import javax.swing.*;

public class Practice
{
    public static void main(String[] args) 
    {
        Jf ob = new Jf();
        ob.setVisible(true);
    }
}
public class Jf extends javax.swing.JFrame
{

BufferedImage img = null;
public Jf() 
{
    initComponents();
    try 
    {
        img = ImageIO.read(new File("1.png"));
    }
    catch (IOException e) 
    {

    }
        Graphics g = img.getGraphics();
        g.drawImage(img, 0, 0, rootPane);
}


   //below the code is auto-generated by netbeans , i did nothing




/**
 * This method is called from within the constructor to initialize the form.
 * WARNING: Do NOT modify this code. The content of this method is always
 * regenerated by the Form Editor.
 */
@SuppressWarnings("unchecked")
// <editor-fold defaultstate="collapsed" desc="Generated Code">                          
private void initComponents() {

    setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);

    javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
    getContentPane().setLayout(layout);
    layout.setHorizontalGroup(
        layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGap(0, 400, Short.MAX_VALUE)
    );
    layout.setVerticalGroup(
        layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
        .addGap(0, 300, Short.MAX_VALUE)
    );

    pack();
}// </editor-fold>                        

/**
 * @param args the command line arguments
 */
public static void main(String args[]) {
    /* Set the Nimbus look and feel */
    //<editor-fold defaultstate="collapsed" desc=" Look and feel setting code (optional) ">
    /* If Nimbus (introduced in Java SE 6) is not available, stay with the default look and feel.
     * For details see http://download.oracle.com/javase/tutorial/uiswing/lookandfeel/plaf.html 
     */
    try {
        for (javax.swing.UIManager.LookAndFeelInfo info : javax.swing.UIManager.getInstalledLookAndFeels()) {
            if ("Nimbus".equals(info.getName())) {
                javax.swing.UIManager.setLookAndFeel(info.getClassName());
                break;
            }
        }
    } catch (ClassNotFoundException ex) {
        java.util.logging.Logger.getLogger(Jf.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
    } catch (InstantiationException ex) {
        java.util.logging.Logger.getLogger(Jf.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
    } catch (IllegalAccessException ex) {
        java.util.logging.Logger.getLogger(Jf.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
    } catch (javax.swing.UnsupportedLookAndFeelException ex) {
        java.util.logging.Logger.getLogger(Jf.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
    }
    //</editor-fold>

    /* Create and display the form */
    java.awt.EventQueue.invokeLater(new Runnable() {
        public void run() {
            new Jf().setVisible(true);
        }
    });
}

// Variables declaration - do not modify                     
// End of variables declaration                   

}

限制:

I can't use JLabel here

所以，请指出我的错误并尝试写出更正，以便我可以轻松理解。提前致谢。

Answer 1

使用 JPanel。将其包含在您的 JFrame 类中:

public static class CustomPanel extends javax.swing.JPanel {
    CustomPanel(width, height) {
        super(width, height);
    }
    void paintComponent(Graphics g) {
        g.drawImage(img, 0, 0, null);
    } 
}

并在您的主要方法中包含以下内容:

ob.add(new CustomPanel(ob.getWidth(), ob.getHeight()));