android 中按键响应实例

下面实例中是在一个Activity 中通过上下左右方向键来控制红色小方块的移动，未作边界检测

效果如下：

RectControlActivity.java

package cie.Rect;import android.app.Activity;import android.os.Bundle;import android.view.Window;import android.view.WindowManager;public class RectControlActivity extends Activity {    /** Called when the activity is first created. */    @Override    public void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        requestWindowFeature(Window.FEATURE_NO_TITLE);//设置窗口没有标题        getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,         WindowManager.LayoutParams.FLAG_FULLSCREEN);//设置全屏显示                setContentView(new RectControlView(this));    }}

RectControlView.java

package cie.Rect;import android.content.Context;import android.graphics.Canvas;import android.graphics.Color;import android.graphics.Paint;import android.view.KeyEvent;import android.view.View;public class RectControlView extends View {int left = 40;int top = 40;int width = 40;int height = 40;public RectControlView(Context context) {super(context);// TODO Auto-generated constructor stubsetFocusable(true);}@Overrideprotected void onDraw(Canvas canvas) {// TODO Auto-generated method stubsuper.onDraw(canvas);Paint paint = new Paint();paint.setColor(Color.RED);canvas.drawRect(left, top, left+width, top+height, paint);postInvalidate();}@Overridepublic boolean onKeyDown(int keyCode, KeyEvent event) {// TODO Auto-generated method stubswitch(keyCode){case KeyEvent.KEYCODE_DPAD_UP:top = top - 10;break;case KeyEvent.KEYCODE_DPAD_DOWN:top = top + 10;break;case KeyEvent.KEYCODE_DPAD_LEFT:left = left - 10;break;case KeyEvent.KEYCODE_DPAD_RIGHT:left = left + 10;break;default:break;}return super.onKeyDown(keyCode, event);}}

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