如何使用 KeyListener 绘制不同的图像？

Question

这只是我的 JFrame 文件。我想在我的角色向下移动时绘制 down.png，在我的角色向上移动时绘制 up.png 等等。我已经浏览了一段时间，但我找不到解决我的问题的方法。如果有人可以将我链接到答案或提供答案，那就太好了！

这是我的代码：

package Michael;

import java.awt.Canvas;
import java.awt.Color;
import java.awt.Graphics;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import javax.imageio.ImageIO;

public class MyCanvas extends Canvas implements KeyListener
{
int myX = 100;
int myY = 100;

BufferedImage down;
{
    try
    {
        down = ImageIO.read(new File("Images/down.png"));
    }

    catch (IOException e)
    {
        System.out.println("Cannot find image file.");
    }
}

BufferedImage downrun;
{
    try
    {
        downrun = ImageIO.read(new File("Images/downrun.png"));
    }

    catch (IOException e)
    {
        System.out.println("Cannot find image file.");
    }
}

BufferedImage left;
{
    try
    {
        left = ImageIO.read(new File("Images/left.png"));
    }

    catch (IOException e)
    {
        System.out.println("Cannot find image file.");
    }
}

BufferedImage right;
{
    try
    {
        right = ImageIO.read(new File("Images/right.png"));
    }

    catch (IOException e)
    {
        System.out.println("Cannot find image file.");
    }
}

BufferedImage runleft;
{
    try
    {
        runleft = ImageIO.read(new File("Images/runleft.png"));
    }

    catch (IOException e)
    {
        System.out.println("Cannot find image file.");
    }
}

BufferedImage runright;
{
    try
    {
        runright = ImageIO.read(new File("Images/runright.png"));
    }

    catch (IOException e)
    {
        System.out.println("Cannot find image file.");
    }
}

BufferedImage swoosh;
{
    try
    {
        swoosh = ImageIO.read(new File("Images/swoosh.png"));
    }

    catch (IOException e)
    {
        System.out.println("Cannot find image file.");
    }
}

BufferedImage swordraise;
{
    try
    {
        swordraise = ImageIO.read(new File("Images/swordraise.png"));
    }

    catch (IOException e)
    {
        System.out.println("Cannot find image file.");
    }
}

BufferedImage up;
{
    try
    {
        up = ImageIO.read(new File("Images/up.png"));
    }

    catch (IOException e)
    {
        System.out.println("Cannot find image file.");
    }
}

BufferedImage uprun;
{
    try
    {
        left = ImageIO.read(new File("Images/uprun.png"));
    }

    catch (IOException e)
    {
        System.out.println("Cannot find image file.");
    }
}

public MyCanvas() // The MyCanvas constructor.
{
    this.setSize(600, 400);
    this.addKeyListener(this);
    this.setBackground(Color.WHITE);
    this.setFocusable(true);
}

public void paint(Graphics g)
{
    g.drawImage(down, myX, myY, 55, 55, null);
    g.drawImage(left, myX, myY, 55, 55, null);
    g.drawImage(right, myX, myY, 55, 55, null);
    g.drawImage(up, myX, myY, 55, 55, null);
} // I don't want to draw every image at the same time, I only want to draw 'up', when the charcter is moving up, etc.

public void moveIt(KeyEvent e)
{
    switch(e.getKeyCode())
    {
        case KeyEvent.VK_DOWN:
            myY += 10;
            break;
        case KeyEvent.VK_UP:
            myY -= 10;
            break;
        case KeyEvent.VK_LEFT:
            myX -= 10;
            break;
        case KeyEvent.VK_RIGHT:
            myX += 10;
            break;
        case KeyEvent.VK_SHIFT:

    }

    repaint();
}

@Override
public void keyPressed(KeyEvent e)
{
    moveIt(e);
}

@Override
public void keyTyped(KeyEvent e)
{
    // TODO Auto-generated method stub
}

@Override
public void keyReleased(KeyEvent e)
{
    // TODO Auto-generated method stub
}
}

非常感谢！

Answer 1

查看Motion Using the Keyboard 中的Motion With Key Bindings 示例。这个例子展示了如何使用Key Bindings（这是更好的解决方案）而不是 KeyListener 来制作动画。

首先了解基本概念，因为您需要进行更改：

1. 现有代码移动一个Component。您可能希望将其更改为 JLabel (with an Icon)。

2. 在创建动作时，您当前只需指定您希望 Component 移动的 x/y 值。现在您需要使用x/y values AND an Icon 创建动作，这样您就可以更改图标以随着每个方向的变化而绘制。

3. 需要修改move(...) 方法以接受Icon，然后更改JLabel 组件的Icon。