JavaSE 键盘事件类（KeyEvent）实现

{相关信息}
键盘事件类(KeyEvent)是容器内的任意组件获得焦点时，组件发生键击事件，当按下释放或键入某一个键时，组件对象将产生该事件。使用键盘事件必须给组件添加一个KeyListener 接口的事件处理器，该接口包含以下 3 个方法：
void keyPressed(KeyEvent e)：按下按键时发生。
void keyReleased(KeyEvent e)：松开按键时发生。
void keyTyped(KeyEvent e)：敲击键盘，发生在按键按下后，按键放开前。

{效果图}

{实现代码}

package sup.orange.learn;

import java.awt.*;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;

/**
 * Created by re-x on 10/31/14.
 */
public class KeyEventDemo extends Frame implements KeyListener {
    TextArea textarea, textarea1;
    Button button;

    public KeyEventDemo () {
        super();
        init();
    }

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

    public void init() {
        setLayout(new GridLayout(3, 1));
        textarea = new TextArea();
        textarea1 = new TextArea();
        add(textarea);

        button = new Button("click me first, then click any other key");
        add(button);
        button.addKeyListener(this);

        add(textarea1);
        addWindowListener(new WindowAdapter() {
            @Override
            public void windowClosing(WindowEvent e) {
                super.windowClosing(e);
                dispose();
                System.exit(0);
            }
        });

        setSize(200, 300);
        setVisible(true);
    }

    public void keyPressed(KeyEvent e) {
        textarea.setText("key pressed");
    }

    public void keyReleased(KeyEvent e) {
        textarea.setText("key released");
    }

    public void keyTyped(KeyEvent e) {
        textarea1.setText(String.valueOf(e.getKeyChar()));
    }
}