无法在我的 JPanel 中绘制图像

Question

我在 GraphicsPanel（JPanel 的扩展）中绘制图像时遇到问题。我尝试使用 getCodeBase()、getDocumentBase()、getResource() 和 BufferedImage 从具有路径名的文件加载。有什么方法可以绘制图像而不必在 JLabel 中使其成为 ImageIcon？

package rpg;

import java.awt.Color;

import java.awt.Graphics;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.awt.event.MouseMotionListener;
import javax.swing.JPanel;
import java.awt.Image;
import java.io.File;
import java.io.IOException;
import javax.imageio.ImageIO;
import javax.swing.ImageIcon;
import javax.swing.JLabel;
import java.awt.image.BufferedImage;

public class GraphicsPanel extends JPanel implements MouseListener, MouseMotionListener {
private WorldBuilder wb;
public int currentTileType = 0;//tile types. 0=bgtile, 1=object, 2=NPC
public String currentTileName = "";
public Image currentTile;

public GraphicsPanel() {
    super();
}

@Override
public void paintComponent(Graphics g) {
    super.paintComponent(g);
    g.setColor(Color.red);
    g.fillRect(0, 0, 720, 528);
    g.drawImage(currentTile, 100, 100, this);//Nothing gets drawn here
}

public void getParameters(WorldBuilder wb) {
    this.wb = wb;
    this.currentTileType = wb.currentTileType;
    this.currentTileName = wb.currentTileName;
    /*
    try {
        currentTile = ImageIO.read(new File("SpriteSheet.png"));
    } catch (IOException e) {
        System.out.println("failed");
    }
    */
    currentTile = new ImageIcon("SpriteSheet.png").getImage();
    repaint();
}

@Override
public void mouseClicked(MouseEvent e) {
    throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods, choose Tools | Templates.
}

@Override
public void mousePressed(MouseEvent e) {
    throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods, choose Tools | Templates.
}

@Override
public void mouseReleased(MouseEvent e) {
    throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods, choose Tools | Templates.
}

@Override
public void mouseEntered(MouseEvent e) {
    throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods, choose Tools | Templates.
}

@Override
public void mouseExited(MouseEvent e) {
    throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods, choose Tools | Templates.
}

@Override
public void mouseDragged(MouseEvent e) {
    throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods, choose Tools | Templates.
}

@Override
public void mouseMoved(MouseEvent e) {
    throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods, choose Tools | Templates.
}

}

Answer 1

cmets 总结：

• SpriteSheet.png 不在ImageIcon(String) 能够找到的位置内。 ImageIcon(String) 期望 String 引用文件系统上的 File，但 SpriteSheet.png 存储在应用程序上下文 (src/rpg/SpriteSheet.png) 中，这使其成为嵌入式资源。
• 使用Class#getResource 加载嵌入式资源，在这种情况下，请确保使用getClass().getResource("SpriteSheet.png") 或getClass().getResource("/rpg/SpriteSheet.png")。
• 在ImageIcon 上使用ImageIO.read。当由于某种原因无法加载图像时，它至少会抛出一个IOException，而ImageIcon 可能会静默失败。
• 确保正在加载资源的GraphicsPanel 的实例与屏幕上的实例相同

Answer 2

以下内容对我有用。 我拿走了你的代码，并将面板添加到 JFrame。另外，在将面板添加到 JFrame 之前，我会调用 getParameters();。

import java.awt.Color;

import java.awt.Graphics;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.awt.event.MouseMotionListener;
import javax.swing.JPanel;
import java.awt.Image;
import java.io.File;
import java.io.IOException;
import javax.imageio.ImageIO;
import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JLabel;
import java.awt.image.BufferedImage;

public class GraphicsPanel extends JPanel implements MouseListener,
        MouseMotionListener {

    public static void main(String args[]) {
        GraphicsPanel s = new GraphicsPanel();
        s.getParameters();
        JFrame frame = new JFrame();
        frame.add(s);       
        frame.setVisible(true);     
    }

    /**
     * 
     */
    private static final long serialVersionUID = 1L;
    public int currentTileType = 0;//tile types. 0=bgtile, 1=object, 2=NPC
    public String currentTileName = "";
    public Image currentTile;

    public GraphicsPanel() {
        super();
    }

    @Override
    public void paintComponent(Graphics g) {
        super.paintComponent(g);
        g.drawImage(currentTile, 100, 100, this);//Nothing gets drawn here
    }

    public void getParameters() {
        currentTile = new ImageIcon("test.jpg").getImage();
        repaint();
    }

    @Override
    public void mouseDragged(MouseEvent arg0) {
        // TODO Auto-generated method stub

    }

    @Override
    public void mouseMoved(MouseEvent arg0) {
        // TODO Auto-generated method stub

    }

    @Override
    public void mouseClicked(MouseEvent arg0) {
        // TODO Auto-generated method stub

    }

    @Override
    public void mouseEntered(MouseEvent arg0) {
        // TODO Auto-generated method stub

    }

    @Override
    public void mouseExited(MouseEvent arg0) {
        // TODO Auto-generated method stub

    }

    @Override
    public void mousePressed(MouseEvent arg0) {
        // TODO Auto-generated method stub

    }

    @Override
    public void mouseReleased(MouseEvent arg0) {
        // TODO Auto-generated method stub

    }   
}