java—图像类在尝试显示图像时返回null

6kkfgxo0  于 2021-06-26  发布在  Java
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我一直在关注2017年majoolwip在youtube上的一个教程(https://youtu.be/4ipejfuznsw)，它是使用eclipseide用java编写的。在这个系列中，他正在构建一个游戏引擎，你可以运行你的游戏。他将指导您如何制作窗口并获取用户输入，但最重要的是，他将教您如何在窗口中显示图像文件。
重要的是我的“image”类无法获取“res”文件夹中图像的url。当我尝试用图像运行程序时，它只会抛出一个我知道是正确的，因为当我打印图像对象的值时，它会将“null”打印到我的控制台。
当前抛出的代码在我的“gamemanager”类中，在这个类中，我的构造函数有一行代码，它创建了一个新的图像对象，并给它一个名为“path”的字符串，该字符串被设置为“res/test.png”。
就我的path变量而言，我已经尝试了许多不同的图像格式，即“/test.png”、“/rougeengine/res/test.png”和“/res/test.png”；他们都没有返回图像。
错误似乎发生在使用
image=imageio.read（image.class.getresourceasstream（路径））；我的cs教授认为类文字可能是问题所在，但他对getresourceasstream（）不太熟悉。
这是我的游戏容器代码：

package com.RougeEngine.Engine;

import java.awt.event.KeyEvent;
import java.awt.event.MouseEvent;

public class GameContainer implements Runnable
{
private Thread thread;
private Window window;
private Renderer renderer;
private Input input;
private AbstractGame game;

private boolean running = false;
private final double UPDATE_CAP = 1.0/60.0;
private int width = 320, height = 240;
private float scale = 3f;
private String Title = "RougeEngine v1.0";

public GameContainer(AbstractGame game)
{
    this.game = game;
}

public void start()
{
    window = new Window(this);
    renderer = new Renderer(this);
    input = new Input(this);

    thread = new Thread(this);
    thread.run();
}

public void stop()
{

}

public void run()
{
    running = true;

    boolean render = false;
    double firstTime = 0;
    double lastTime = System.nanoTime() / 1000000000.0;
    double passedTime = 0;
    double unprocessedTime = 0;

    double frameTime = 0;
    int frames = 0;
    int fps = 0;

    while(running)
    {
        render = false;

        firstTime = System.nanoTime() / 1000000000.0;
        passedTime = firstTime - lastTime;
        lastTime = firstTime;

        unprocessedTime = unprocessedTime + passedTime;
        frameTime = frameTime + passedTime;

        while(unprocessedTime >= UPDATE_CAP)
        {
            unprocessedTime = unprocessedTime - UPDATE_CAP;
            render = true;

            game.update(this, (float)UPDATE_CAP);

            input.update();

            if(frameTime >= 1.0)
            {
                frameTime = 0;
                fps = frames;
                frames = 0;
                System.out.println("FPS:"+fps);
            }
        }
        if(render)
        {
            renderer.clear();
            game.render(this, renderer);
            window.update();
            frames++;
        }
        else
        {
            try 
            {
                Thread.sleep(1);
            } 
            catch (InterruptedException e) 
            {
                e.printStackTrace();
            }
        }
    }
    dispose();
}

private void dispose()
{

}

public int getWidth() {
    return width;
}

public void setWidth(int width) {
    this.width = width;
}

public int getHeight() {
    return height;
}

public void setHeight(int height) {
    this.height = height;
}

public float getScale() {
    return scale;
}

public void setScale(float scale) {
    this.scale = scale;
}

public String getTitle() {
    return Title;
}

public void setTitle(String title) {
    Title = title;
}

public Window getWindow() {
    return window;
}

public Input getInput() {
    return input;
}
}

这是我的窗口代码：

package com.RougeEngine.Engine;

import java.awt.BorderLayout;
import java.awt.Canvas;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.image.BufferStrategy;
import java.awt.image.BufferedImage;
import javax.swing.JFrame;

public class Window 
{
private JFrame frame;
private BufferedImage image;
private Canvas canvas;
private BufferStrategy bs;
private Graphics g;

public Window(GameContainer gc)
{
    image = new BufferedImage(gc.getWidth(),gc.getHeight(), BufferedImage.TYPE_INT_RGB);
    canvas = new Canvas();
    Dimension s = new Dimension((int)(gc.getWidth() * gc.getScale()), (int)(gc.getHeight() * gc.getScale()));
    canvas.setPreferredSize(s);
    canvas.setMaximumSize(s);
    canvas.setMinimumSize(s);

    frame = new JFrame(gc.getTitle());
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setLayout(new BorderLayout());
    frame.add(canvas, BorderLayout.CENTER);
    frame.pack();
    frame.setLocationRelativeTo(null);
    frame.setResizable(false);
    frame.setVisible(true);

    canvas.createBufferStrategy(2);
    bs = canvas.getBufferStrategy();
    g = bs.getDrawGraphics();
}

public JFrame getFrame() {
    return frame;
}

public void update()
{
    g.drawImage(image, 0, 0, canvas.getWidth(), canvas.getHeight(),null);
    bs.show();
}

public BufferedImage getImage() {
    return image;
}

public Canvas getCanvas() {
    return canvas;
}
}

下面是我的代码：

package com.RougeEngine.Engine;

import java.awt.image.DataBufferInt;

import com.RougeEngine.Engine.gfx.Image;

public class Renderer 
{
private int pW, pH;
private int[] p;

public Renderer(GameContainer gc)
{
    pW = gc.getWidth();
    pH = gc.getHeight();
    p = ((DataBufferInt)gc.getWindow().getImage().getRaster().getDataBuffer()).getData();
}

public void clear()
{
    for(int i = 0; i < p.length; i++)
    {
        p[i] = 0;
    }
}

public void setPixel(int x, int y, int value)
{
    if((x < 0 || x >= pH || y < 0 || y >= pH) || value == 0xffff00ff)
    {
        return;
    }

    p[x + y * pW] = value;
}

public void drawImage(Image image, int offX, int offY)
{
    for(int y = 0; y < image.getH(); y++)
    {
        for(int x = 0; x < image.getW(); x++)
        {
            setPixel(x+ offX, y + offY, image.getP()[x + y * image.getW()]);
        }
    }
}
}

这是我的输入代码：

package com.RougeEngine.Engine;

import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.awt.event.MouseMotionListener;
import java.awt.event.MouseWheelEvent;
import java.awt.event.MouseWheelListener;

public class Input implements KeyListener, MouseListener, MouseMotionListener, MouseWheelListener
{
private GameContainer gc;

private final int NUM_KEYS = 256;
private boolean[] keys = new boolean[NUM_KEYS];
private boolean[] keysLast = new boolean[NUM_KEYS];

private final int NUM_BUTTONS = 5;
private boolean[] buttons = new boolean[NUM_BUTTONS];
private boolean[] buttonsLast = new boolean[NUM_BUTTONS];

private int mouseX, mouseY;
private int scroll;

public Input(GameContainer gc)
{
    this.gc = gc;
    mouseX = 0;
    mouseY = 0;
    scroll = 0;

    gc.getWindow().getCanvas().addKeyListener(this);
    gc.getWindow().getCanvas().addMouseMotionListener(this);
    gc.getWindow().getCanvas().addMouseListener(this);
    gc.getWindow().getCanvas().addMouseWheelListener(this);
}

public void update()
{
    scroll = 0;
    for(int i = 0; i < NUM_KEYS; i++)
    {
        keysLast[i] = keys[i];
    }
    for(int i = 0; i < NUM_BUTTONS; i++)
    {
        buttonsLast[i] = buttons[i];
    }
}

public boolean isKey(int keyCode)
{
    return keys[keyCode];
}
public boolean isKeyUp(int keyCode)
{
    return !keys[keyCode] && keysLast[keyCode];
}
public boolean isKeyDown(int keyCode)
{
    return keys[keyCode] && !keysLast[keyCode];
}

public boolean isButton(int button)
{
    return buttons[button];
}
public boolean isButtonUp(int button)
{
    return !buttons[button] && buttonsLast[button];
}
public boolean isButtonDown(int button)
{
    return buttons[button] && !buttonsLast[button];
}

@Override
public void mouseWheelMoved(MouseWheelEvent e) 
{
     scroll = e.getWheelRotation();
}

@Override
public void mouseDragged(MouseEvent e) 
{
    mouseX = (int)(e.getX() / gc.getScale());
    mouseY = (int)(e.getY() / gc.getScale());
}

@Override
public void mouseMoved(MouseEvent e) 
{
     mouseX = (int)(e.getX() / gc.getScale());
     mouseY = (int)(e.getY() / gc.getScale());
}

@Override
public void mouseClicked(MouseEvent e) 
{

}

@Override
public void mousePressed(MouseEvent e) 
{
     buttons[e.getButton()] = true;
}

@Override
public void mouseReleased(MouseEvent e) 
{
     buttons[e.getButton()] = false;
}

@Override
public void mouseEntered(MouseEvent e) 
{ 

}

@Override
public void mouseExited(MouseEvent e) 
{

}

@Override
public void keyTyped(KeyEvent e) 
{

}

@Override
public void keyPressed(KeyEvent e) 
{
     keys[e.getKeyCode()] = true;
}

@Override
public void keyReleased(KeyEvent e) 
{
     keys[e.getKeyCode()] = false;
}

public int getMouseX() {
    return mouseX;
}

public int getMouseY() {
    return mouseY;
}

public int getScroll() {
    return scroll;
}
}

这是我的游戏：

package com.RougeEngine.Engine;

public abstract class AbstractGame 
{
public abstract void update(GameContainer gc, float dt);
public abstract void render(GameContainer gc, Renderer r);

}

这是我的图像代码：

package com.RougeEngine.Engine.gfx;

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

import javax.imageio.ImageIO;

public class Image 
{
private int w,h;
private int[] p;
public Image(String path)
{
    BufferedImage image = null;
    System.out.println(Image.class.getResourceAsStream(path));
    try 
    {
        image = ImageIO.read(Image.class.getResourceAsStream(path));
    } 
    catch (IOException e) 
    {
        e.printStackTrace();
    }

    w = image.getWidth();
    h = image.getHeight();
    p = image.getRGB(0, 0, w, h, null, 0, w);

    image.flush();
}

public int getW() 
{
    return w;
}
public void setW(int w) 
{
    this.w = w;
}
public int getH() 
{
    return h;
}
public void setH(int h) 
{
    this.h = h;
}
public int[] getP() 
{
    return p;
}
public void setP(int[] p) 
{
    this.p = p;
}
}

以下是我的gamemanager代码：

package com.RougeEngine.Game;

import java.awt.event.KeyEvent;

import com.RougeEngine.Engine.AbstractGame;
import com.RougeEngine.Engine.GameContainer;
import com.RougeEngine.Engine.Renderer;
import com.RougeEngine.Engine.gfx.Image;

public class GameManager extends AbstractGame
{

private Image image;

public GameManager()
{
    image = new Image("res/test.png");
}

public static void main(String[] args) 
{
    GameContainer gc = new GameContainer(new GameManager());
    gc.start();
}

@Override
public void update(GameContainer gc, float dt) 
{
    if(gc.getInput().isKeyDown(KeyEvent.VK_A))
    {
        System.out.println("A was pressed");
    }
}

@Override
public void render(GameContainer gc, Renderer r) 
{

}

}

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