使用 PaintComponent Java 绘制图像
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Image drawing with PaintComponent Java
提问by Igor Meszaros
I'm studying java currently, and yet again I ran into a code in the book which doesn't wanna work and i can't figure out why. This code snippet is from Head First Java
我目前正在学习 Java，但我又一次遇到了书中的一段代码，该代码不想工作，我不知道为什么。此代码片段来自 Head First Java
import javax.swing.*;
import java.awt.*;
public class SimpleGui {
public static void main (String[] args){
JFrame frame = new JFrame();
DrawPanel button = new DrawPanel();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().add(button);
frame.setSize(300,300);
frame.setVisible(true);
}
}
import java.awt.*;
import java.lang.*;
public class DrawPanel extends JPanel {
private Image image;
public DrawPanel(){
image = new ImageIcon("cat2.jpg").getImage();
}
public void paintComponent(Graphics g){
g.drawImage(image,3,4,this);
}
}
the image is in the same directory where my class files are, and the image is not showing. What am i missing here?
该图像位于我的类文件所在的同一目录中，并且该图像未显示。我在这里缺少什么？
采纳答案by alex2410
1) In your paintComponent()you must to call super.paintComponent(g);. Read more about custom paintings.
1) 在paintComponent()你必须调用super.paintComponent(g);. 阅读更多关于定制绘画的信息。
2) instead of Imageuse BufferedImage, because Image its abstrat wrapper.
2) 而不是Imageuse BufferedImage，因为 Image 是它的抽象包装器。
3)use ImageIOinstead of creating Imagelike this new ImageIcon("cat2.jpg").getImage();
3）使用ImageIO而不是Image像这样创建new ImageIcon("cat2.jpg").getImage();
4)Use URLfor resources inside your project.
4）URL用于项目内的资源。
I changed your code and it helps you:
我更改了您的代码，它可以帮助您：
class DrawPanel extends JPanel {
private BufferedImage image;
public DrawPanel() {
URL resource = getClass().getResource("cat2.jpg");
try {
image = ImageIO.read(resource);
} catch (IOException e) {
e.printStackTrace();
}
}
public void paintComponent(Graphics g) {
super.paintComponent(g);
g.drawImage(image, 3, 4, this);
}
}
