import javax.swing.*;
import java.awt.event.KeyListener;
import java.awt.event.KeyEvent;

public class KeyListenerFrame extends JFrame implements KeyListener {
    private JTextArea jta=new JTextArea(10,10);

    public KeyListenerFrame(String title){
        super(title);

        jta.addKeyListener(this);
        this.getContentPane().add(jta);
        this.pack();
        this.setVisible(true);
        this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        this.setLocationRelativeTo(null);
    }

    public static void main(String[] args) {
        new  KeyListenerFrame("demo");
    }

    @Override
    public void keyTyped(KeyEvent e) {
        //To change body of implemented methods use File | Settings | File Templates.
//        if(e.getKeyCode()==KeyEvent.VK_DOWN){
//              jta.append("↓");
//        }

    }

    @Override
    public void keyPressed(KeyEvent e) {
         switch(e.getKeyCode()){
            case KeyEvent.VK_DOWN:
                jta.append("↓");
                break;
            case KeyEvent.VK_UP:
                jta.append("↑");
                break;
            case KeyEvent.VK_LEFT:
                jta.append("←");
                break;
            case KeyEvent.VK_RIGHT:
                jta.append("→");
                break;
//            default:
//                jta.append(""+e.getKeyChar());
        }
    }

    @Override
    public void keyReleased(KeyEvent e) {
        //To change body of implemented methods use File | Settings | File Templates.
    }
}

------解决方案--------------------

这里给你贴一个具体的实例，但是还有点小问题就是 左箭头的具体实现要再用程序控制光标
Java code

import javax.swing.*;
import java.awt.event.KeyListener;
import java.awt.event.KeyEvent;

public class KeyListenerFrame extends JFrame implements KeyListener {
    private JTextArea jta=new JTextArea(10,10);

    public KeyListenerFrame(String title){
        super(title);

        jta.addKeyListener(this);
        this.getContentPane().add(jta);
        this.pack();
        this.setVisible(true);
        this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        this.setLocationRelativeTo(null);
    }

    public static void main(String[] args) {
        new  KeyListenerFrame("demo");
    }

    @Override
    public void keyTyped(KeyEvent e) {
        //To change body of implemented methods use File | Settings | File Templates.
//        if(e.getKeyCode()==KeyEvent.VK_DOWN){
//              jta.append("↓");
//        }

    }

    @Override
    public void keyPressed(KeyEvent e) {
         switch(e.getKeyCode()){
            case KeyEvent.VK_DOWN:
                jta.append("↓");
                break;
            case KeyEvent.VK_UP:
                jta.append("↑");
                break;
            case KeyEvent.VK_LEFT:
                jta.append("←");
                break;
            case KeyEvent.VK_RIGHT:
                jta.append("→");
                break;
//            default:
//                jta.append(""+e.getKeyChar());
        }
    }

    @Override
    public void keyReleased(KeyEvent e) {
        //To change body of implemented methods use File | Settings | File Templates.
    }
}