Java游戏无法读取图像文件

Question

由于某种原因，我的程序找不到图像。我已经尝试了一切并确保文件路径是准确的。在我之前的游戏中它运行得很好，但现在它根本找不到图像。

实体类

package Entities;

import java.awt.Graphics2D;
import java.awt.image.BufferedImage;
import java.io.IOException;

import javax.imageio.ImageIO;

public class Entity
{
    public double x, y, width, height, dx, dy;

    public BufferedImage image;

    public Entity(String s)
    {
        try
        {       //error occurs here
            image = ImageIO.read(getClass().getResourceAsStream(s)); 
        } 
        catch (IOException e)
        {
            e.printStackTrace();
        }

        width = image.getWidth();
        height = image.getHeight();
    }

    public void update()
    {
        x += dx;
        y += dy;
    }

    public void draw(Graphics2D g)
    {
        g.drawImage(image, (int)x, (int)y, null);
    }
}

GamePanel类

package Main;

//import java.awt.Container;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import java.awt.image.BufferedImage;

import javax.swing.JPanel;

import Entities.Entity;

@SuppressWarnings("serial")
public class GamePanel extends JPanel implements Runnable, KeyListener
{
    public static final int WIDTH = 320;
    public static final int HEIGHT = 240;
    public static final int SCALE = 2;

    //game thread
    private Thread thread;
    private boolean running;
    private int fps = 60;
    private long targetTime = 1000/fps;

    //image
    private BufferedImage image;
    private Graphics2D g;

    //test
    public Entity e;

    public GamePanel()
    {
        super();
        setPreferredSize(new Dimension(WIDTH * SCALE, HEIGHT * SCALE));
        setFocusable(true);
        requestFocus();
    }

    public void addNotify()
    {
        super.addNotify();
        if(thread == null)
        {
            thread = new Thread(this);
            addKeyListener(this);
            thread.start();
        }
    }

    public void init()
    {
        image = new BufferedImage(WIDTH, HEIGHT, BufferedImage.TYPE_INT_RGB);
        g = (Graphics2D) image.getGraphics();
        running = true;

        e = new Entity("Resources/Test/test.png");
    }

    @Override
    public void keyPressed(KeyEvent key) 
    {
        //p1.keyPressed(key.getKeyCode());
    }

    @Override
    public void keyReleased(KeyEvent key) 
    {
        //p1.keyReleased(key.getKeyCode());
    }

    @Override
    public void keyTyped(KeyEvent arg0) 
    {

    }

    @Override
    public void run() 
    {
        init();

        long start;
        long elapsed;
        long wait;

        //game loop
        while(running)
        {
            start = System.nanoTime();

            update();
            draw();
            drawToScreen();

            elapsed = System.nanoTime() - start;

            wait = targetTime - elapsed/1000000;

            if(wait < 0)
            {
                wait = 5;
            }

            try
            {
                Thread.sleep(wait);
            }
            catch(Exception e)
            {
                e.printStackTrace();
            }
        }

    }

    private void drawToScreen() 
    {
        Graphics g2 = getGraphics();
        g2.drawImage(image, 0, 0, WIDTH * SCALE, HEIGHT * SCALE, null);
        g2.dispose();

    }

    private void draw() 
    {
        //e.draw(g);
    }

    private void update() 
    {

    }
}

这是错误

Exception in thread "Thread-2" java.lang.IllegalArgumentException: input == null!
at javax.imageio.ImageIO.read(Unknown Source)
at Entities.Entity.<init>(Entity.java:19)
at Main.GamePanel.init(GamePanel.java:67)
at Main.GamePanel.run(GamePanel.java:93)
at java.lang.Thread.run(Unknown Source)

Answer 1

路径Resources/Test/test.png建议从用于尝试加载类引用的位置开始的相对路径。

由于您正在使用 Entity 类来尝试加载图像，并且 Entity 驻留在 Entities 包中，因此这将生成一个/Entities/Resources/Test/test.png 的绝对路径(来自类路径的上下文)，这显然是不正确的。

尝试使用 /Resources/Test/test.png (假设 Resources 位于路径树的顶部，例如...

+ Resources
  + Test
    - test.png
+ Entities
  - Entity
+ Main
  - GamePanel