public class ClockView extends View implements Handler.Callback {

 //定義一個(gè)畫筆
 private Paint paint;
 //定義個(gè)畫小時(shí)指針的路徑
 private Path hour;
 //定義一個(gè)畫分針的路徑
 private Path minute;
 //定義一個(gè)Handler來(lái)實(shí)現(xiàn)時(shí)鐘跑動(dòng)效果
 private Handler handler = new Handler(this);

 public ClockView(Context context) {
  this(context, null);
 }

 public ClockView(Context context, AttributeSet attrs) {
  this(context, attrs, 0);
 }

 public ClockView(Context context, AttributeSet attrs, int defStyleAttr) {
  super(context, attrs, defStyleAttr);
  //創(chuàng)建一個(gè)畫筆
  this.paint = new Paint();
  //創(chuàng)建一個(gè)時(shí)針路徑，用于繪制時(shí)針
  hour = new Path();
  //首先將點(diǎn)定位到時(shí)針尾部，所有的坐標(biāo)，大家可以根據(jù)圓心點(diǎn)去尋找對(duì)應(yīng)的點(diǎn)
  hour.moveTo(500, 380);
  //然后與(185,500)連接一條線
  hour.lineTo(485, 500);
  //然后與(500,515)連接一條線
  hour.lineTo(500, 515);
  //最后繪制成一個(gè)完整的時(shí)針線條了，效果為圖中的綠色線條
  hour.lineTo(515, 500);
  //創(chuàng)建一個(gè)分針路徑
  minute = new Path();
  minute.moveTo(500, 350);
  minute.lineTo(490, 500);
  minute.lineTo(500, 510);
  //最后連接成一條分針線條
  minute.lineTo(510, 500);
  //一開始就發(fā)送消息，讓時(shí)鐘開始運(yùn)行
  handler.sendEmptyMessage(0);

 }

 @TargetApi(Build.VERSION_CODES.N)
 @Override
 protected void onDraw(Canvas canvas) {
  super.onDraw(canvas);
  //首先設(shè)置畫布為黑色
  canvas.drawColor(0xff000000);
  //獲取屏幕的寬，和高的比例，選取最小的比例，這樣就能讓圖片位于中間了。
  float scale = Math.min(getWidth() / 1000.0f, getHeight() / 1000.0f);
  //設(shè)置畫布的比例
  canvas.scale(scale, scale);
  //將圖片繪制在屏幕的中間
  canvas.translate((getWidth() / scale - 1000) / 2, (getHeight() / scale - 1000) / 2);
  //設(shè)置畫筆類型為空心的
  paint.setStyle(Paint.Style.STROKE);
  //顏色為白色
  paint.setColor(0xffffffff);
  //畫筆的粗細(xì)
  paint.setStrokeWidth(5);
  //將上面所有繪制的內(nèi)容進(jìn)行保存一下
  canvas.save();
  //開始繪制一個(gè)時(shí)鐘外圓
  canvas.drawCircle(500, 500, 200, paint);
  //通過(guò)for循環(huán)繪制12個(gè)小時(shí)的時(shí)鐘刻度
  for (int i = 0; i < 12; i++) {
   if (i % 3 == 0) {//繪制12 3 6 9點(diǎn)時(shí)刻
    paint.setStrokeWidth(5);//設(shè)置粗度為5
    canvas.drawLine(500, 300, 500, 320, paint);
   } else {
    paint.setStrokeWidth(2);
    canvas.drawLine(500, 300, 500, 315, paint);
   }
   canvas.rotate(30, 500, 500);//將圓圍繞圓點(diǎn)旋轉(zhuǎn)30度,每30度繪制一個(gè)刻度
  }
  paint.setStrokeWidth(3);
  paint.setColor(0xff00ff00);
  paint.setStyle(Paint.Style.FILL);
  //定義一個(gè)Calendar時(shí)鐘類
  Calendar calendar = Calendar.getInstance();
  //將上面所有繪制的東西保存下來(lái)
  canvas.save();
  //通過(guò)獲取系統(tǒng)的時(shí)鐘，然后繪制到對(duì)應(yīng)的時(shí)針
  canvas.rotate(calendar.get(Calendar.HOUR) * 30 + calendar.get(Calendar.MINUTE), 500, 500);
  //繪制時(shí)針
  canvas.drawPath(hour, paint);
  //重繪上一次的時(shí)鐘
  canvas.restore();
  //設(shè)置分針的顏色為紅色
  paint.setColor(0xffff0000);
  //根據(jù)系統(tǒng)獲取的時(shí)間旋轉(zhuǎn)到對(duì)應(yīng)的角度
  canvas.rotate(calendar.get(Calendar.MINUTE) * 6 + calendar.get(Calendar.SECOND) * 0.1f, 500, 500);
  //繪制分針
  canvas.drawPath(minute, paint);
  paint.setColor(Color.WHITE);
  paint.setStrokeWidth(2);
  canvas.save();
  canvas.rotate(calendar.get(Calendar.SECOND) * 6, 500, 500);
  //繪制秒針
  canvas.drawLine(500, 330, 500, 510, paint);
  canvas.restore();
  canvas.save();
 }

 /**
  * 通過(guò)Handler更新時(shí)鐘走向
  * @param message
  * @return
  */
 @Override
 public boolean handleMessage(Message message) {
  switch (message.what) {
   case 0:
    //重新掉用onDraw方法
    invalidate();
    //每隔一秒繪制一次
    handler.sendEmptyMessageDelayed(0, 1000);
    break;
  }
  return true;
 }
}