Imageio读取器错误和问题

Question

我在Java中为一个非常基本的游戏创建了一个非常基本的英语项目，该项目将在几天内到期(任何答案都非常感谢！(。

我在编译和加载图像方面遇到问题：在我的IDE，Intellij中，我可以轻松地加载图像，但使用直接路径(例如src/main/resources/assets/image.png(。但是，我的程序结构化，因此可以与Gradle一起使用，实际上我只需要assets/image.png即可。

但是，主要问题是，当我运行./gradlew jar将其编译到可执行文件的.jar文件中时，无论我使用哪种路径，它都永远不会找到图像。

任何人可以帮助提出一些建议吗？我尝试了许多与Imageio等的方法。我找不到在stackoverflow上使用的解决方案。

这是我的代码：(一些无关紧要的东西，例如钥匙录。这确实是混乱且不良的代码

public class Game implements Runnable {
    final int WIDTH = 1000;
    final int HEIGHT = 700;
    JFrame frame;
    Canvas canvas;
    BufferStrategy bufferStrategy;
    public Game() {
        frame = new JFrame("Hamlet Game by Brian Shin");
        JPanel panel = (JPanel) frame.getContentPane();
        panel.setPreferredSize(new Dimension(WIDTH, HEIGHT));
        panel.setLayout(null);
        canvas = new Canvas();
        canvas.setBounds(0, 0, WIDTH, HEIGHT);
        canvas.setIgnoreRepaint(true);
        panel.add(canvas);
        canvas.addMouseListener(new MouseControl());
        canvas.addKeyListener(new KeyControl());
        frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
        frame.pack();
        frame.setResizable(false);
        frame.setVisible(true);
        canvas.createBufferStrategy(2);
        bufferStrategy = canvas.getBufferStrategy();
        canvas.requestFocus();
    }
    //Key adapter and Mouse stuff here
    Sprite background;
    Sprite hamlet;
    public void initGame() {
        // TESTING
        /*ImageIcon bg = new ImageIcon("src/main/resources/bg.png");
        background = new Sprite(bg.getImage(), 0, 0);
        ImageIcon hammy = new ImageIcon("src/main/resources/hamlet.png");
        hamlet = new Sprite(hammy.getImage(), 300, 300); */
        BufferedImage bg;
        BufferedImage hammy;
        try {
            bg = ImageIO.read(new File("src/main/resources/assets/bg.png")); // TODO: get it working with .jar compiler
            hammy = ImageIO.read(new File("src/main/resources/assets/hamlet.png")); // src/main/resources/assets
            background = new Sprite(bg, 0, 0);
            hamlet = new Sprite(hammy, 300, 300);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
    long desiredFPS = 60;
    long desiredDeltaLoop = (1000*1000*1000)/desiredFPS;
    boolean running = true;
    public void run() {
        long beginLoopTime;
        long endLoopTime;
        long currentUpdateTime = System.nanoTime();
        long lastUpdateTime;
        long deltaLoop;
        initGame();
        while(running) {
            beginLoopTime = System.nanoTime();
            render();
            lastUpdateTime = currentUpdateTime;
            currentUpdateTime = System.nanoTime();
            update((int) ((currentUpdateTime - lastUpdateTime)/(1000*1000)));
            endLoopTime = System.nanoTime();
            deltaLoop = endLoopTime - beginLoopTime;
            if(deltaLoop > desiredDeltaLoop) {
                //Do nothing.
            } else {
                try {
                    Thread.sleep((desiredDeltaLoop - deltaLoop)/(1000*1000));
                } catch(InterruptedException e) {
                    //Do nothing.
                }
            }
        }
    }
    private void render() {
        Graphics2D g = (Graphics2D) bufferStrategy.getDrawGraphics();
        g.clearRect(0, 0, WIDTH, HEIGHT);
        g.drawImage(background.getImage(), background.getX(), background.getY(), null);
        render(g);
        g.dispose();
        bufferStrategy.show();
    }
    /**
     * Update method.
     */
    protected void update(int deltaTime) {
    }
    /**
     * Main rendering method.
     */
    protected void render(Graphics2D g) {
        g.drawImage(hamlet.getImage(), hamlet.getX(), hamlet.getY(), null);
    }
    public boolean collision(Sprite s) {
        return (s.getX() < 0 || s.getY() < 0 || s.getX() > (WIDTH - 30) || s.getY() > (HEIGHT - 45));
    }
    public Direction getCollDir(Sprite s) {
        if(s.getX() < 0) {
           return Direction.LEFT;
        } else if(s.getY() < 0) {
            return Direction.UP;
        } else if(s.getX() > (WIDTH - 30)) {
            return Direction.RIGHT;
        } else if(s.getY() > (HEIGHT - 45)) {
            return Direction.DOWN;
        } else {
            return Direction.NONE;
        }
    }
    public static void main(String [] args) {
        Game ex = new Game();
        new Thread(ex).start();
    }
} 

产生的错误是：

javax.imageio.IIOException: Can't read input file!
        at javax.imageio.ImageIO.read(Unknown Source)
        at Game.initGame(Game.java:151)
        at Game.run(Game.java:172)
        at java.lang.Thread.run(Unknown Source)
Exception in thread "Thread-2" java.lang.NullPointerException
        at Game.render(Game.java:201)
        at Game.run(Game.java:177)
        at java.lang.Thread.run(Unknown Source)

Answer 1

您应该使用ImageIO.read(InputStream input)而不是ImageIO.read(File file)。
然后通过将文件作为classPath资源加载作为流传递作为流：Game.class.gerResourceAsStream("/bg.png");

如果图像位于罐子内的目录下方，只需附加文件名的目录路径。