java - 从 C 驱动器以 Java 代码加载图像

Question

我是 Java 新手。我只是想在 JFrame 中加载图像作为背景。我想做的是从 C 驱动器(那不是我的工作区)获取图像，所以我在 Board.java 中做了什么:

   ImageIcon i = new ImageIcon("C:/image.png");
   img =i.getImage();

并试着把它画成这样:

    public void paint(Graphics g )
    { 
    super.paint(g);
    Graphics2D  g2d= (Graphics2D) g;
    g2d.drawImage(img, 0, 100, null);
    }

然后我像这样调用我的主类

   public static void main(String[] args) 
   {
    JFrame frame= new JFrame(" Game") ;
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setSize(1200, 365);
    frame.setVisible(true);
    frame.add(new Board());

   }

但是我没有显示任何图像，那么添加 Image 是否合法？

Answer 1

• 不要覆盖JFrame中的paint()
• 不要在 JFrame 上调用 setSize()，而是在将其设置为可见之前使用 JFrame#pack()
• 养成使用 / 的习惯，因为无论哪个平台都支持它。

这是我做的一个例子:

• 创建JPanel/JLabel实例
• 覆盖JPanel/JLabel中的paintComponent(..)
• 覆盖 getPreferredSize() 以返回与 Image 正确调整大小的维度/组件
• 将JPanel/Jlabel添加到JFrame实例
• 通过JFrame#pack()打包JFrame
• 设置JFrame可见

测试.java:

//necessary imports
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Image;
import java.io.File;
import javax.imageio.ImageIO;
import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;

public class Test {

    static String filename = "c:/test.jpg";//your file path and name here use / as it will work on linux platforms too so get into the habbit

    /**
     * Default constructor
     */
    public Test() throws Exception {
        initComponents();
    }

    /**
     * Initialize GUI and components (including ActionListeners etc)
     */
    private void initComponents() throws Exception {
        JFrame frame = new JFrame("Test");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        final Image background = ImageIO.read(new File(filename));
        final Dimension jpanelDimensions = new Dimension(new ImageIcon(background).getIconWidth(), new ImageIcon(background).getIconHeight());

        frame.add(new JPanel() {
            @Override
            protected void paintComponent(Graphics grphcs) {
                super.paintComponent(grphcs);
                grphcs.drawImage(background, 0, 0, null);
            }

            //return a JPanel that matches images size
            @Override
            public Dimension getPreferredSize() {
                return jpanelDimensions;
            }
        });

        frame.setResizable(false);

        //pack frame (size JFrame to match preferred sizes of added components and set visible
        frame.pack();
        frame.setVisible(true);
    }

    public static void main(String[] args) {

        /**
         * Create GUI and components on Event-Dispatch-Thread
         */
        javax.swing.SwingUtilities.invokeLater(new Runnable() {
            @Override
            public void run() {
                try {
                    //set nimbus look and feel
                    for (UIManager.LookAndFeelInfo info : UIManager.getInstalledLookAndFeels()) {
                        if ("Nimbus".equals(info.getName())) {
                            UIManager.setLookAndFeel(info.getClassName());
                            break;
                        }
                    }
                } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException e) {
                    e.printStackTrace();
                }
                try {
                    //create GUI instance
                    Test test = new Test();
                } catch (Exception ex) {
                    ex.printStackTrace();
                }
            }
        });
    }
}