Baby 未附加到组件层次结构，因此不会接收任何键事件。事实上，这种设计毫无意义。没有必要 Bady 延伸 JPanel 完全。
相反，利用 GamePlayPanel 直接地

import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Image;
import java.awt.event.ActionEvent;
import java.awt.event.KeyEvent;
import java.util.*;
import javax.swing.AbstractAction;
import javax.swing.ImageIcon;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.KeyStroke;

public class Test {

    public static void main(String[] args) {
        new Test();
    }

    public Test() {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                JFrame frame = new JFrame();
                frame.add(new GamePlayPanel());
                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }
        });
    }

    public class GamePlayPanel extends JPanel {

        private Baby bayi;

        public GamePlayPanel() {
            //An baby object
            bayi = new Baby(100, 410, 5);

            //this is where my keyBinding initialized
            getInputMap(JComponent.WHEN_IN_FOCUSED_WINDOW).put(KeyStroke.getKeyStroke(KeyEvent.VK_RIGHT, 0), "moveRight");
            getActionMap().put("moveRight", new Move_it(1));

        }

        @Override
        public Dimension getPreferredSize() {
            return new Dimension(1200, 500);
        }

        //this is the action class that i want to put in my keybinding
        private class Move_it extends AbstractAction {

            int code;

            public Move_it(int code) {
                this.code = code;
            }

            @Override
            public void actionPerformed(ActionEvent e) {
                // TODO Auto-generated method stub
                System.out.println("test\n");
                if (this.code == 1) {
                    bayi.moveRight();
                }
                repaint();
            }
        }

        //To draw my baby
        @Override
        public void paintComponent(Graphics g) {
            super.paintComponent(g);
            bayi.draw(g);
        }

    }

    public class Baby {

        float x, y;
        float speed;
        Image current;
        private List<Image> ImgPool;
        private int Current;

        public Baby(float x, float y, float speed) {
            // TODO Auto-generated constructor stub
            this.x = x;
            this.y = y;
            this.speed = speed;
            ImgPool = new ArrayList<Image>();

            //These are just some images that i use to build my moving baby
            ImgPool.add(new ImageIcon("baby1_50.png").getImage());
            ImgPool.add(new ImageIcon("baby2_50.png").getImage());
            ImgPool.add(new ImageIcon("baby1_50.png").getImage());
            ImgPool.add(new ImageIcon("baby3_50.png").getImage());
            this.current = ImgPool.get(0);
            this.Current = 0;
        }

        //The action that i want my baby to do when a key is pressed
        public void moveRight() {
            if (x > 600) {
                return;
            }
            this.x += speed;
            if (this.Current == 3) {
                this.Current = 0;
            } else {
                this.Current++;
            }
            this.current = this.ImgPool.get(Current);
        }

        public void draw(Graphics g) {
            g.drawImage(this.current, (int) this.x, (int) this.y, null);
        }

    }
}