public class Watch extends View {
 private Paint mPaint;
 private Context context;

 public Watch(Context context) {
  super(context);
  this.context = context;
  init();
 }

 public Watch(Context context, @Nullable AttributeSet attrs) {
  super(context, attrs);
  this.context = context;
  init();
 }


 public Watch(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
  super(context, attrs, defStyleAttr);
 }

 private void init() {
  mPaint = new Paint();
  //抗鋸齒
  mPaint.setAntiAlias(true);
  mPaint.setColor(Color.BLACK);
  //分三種，STROKE之繪制輪廓，不繪制內(nèi)容；FILL，只繪制內(nèi)容；FILL_AND_STROKE，內(nèi)容和輪廓都繪制
  mPaint.setStyle(Paint.Style.STROKE);
 }

//設(shè)置線(xiàn)寬，線(xiàn)寬默認(rèn)是1 
mPaint.setStrokeWidth(2);
//在屏幕中心畫(huà)圓，半徑為屏幕的1/3
canvas.drawCircle(getWidth() / 2, getHeight() / 2, getWidth() / 3, mPaint);

//整個(gè)屏幕中心為圓心點(diǎn)
mPaint.setStrokeWidth(5);
canvas.drawPoint(getWidth() / 2, getHeight() / 2, mPaint);

//安卓坐標(biāo)系默認(rèn)實(shí)在左上角的，現(xiàn)在我們需要將坐標(biāo)軸移動(dòng)到圓心位置，這樣利于我們繪制線(xiàn)
mPaint.setStrokeWidth(1);
//坐標(biāo)原點(diǎn)平移到圓心的位置
canvas.translate(getWidth() / 2, getHeight() / 2);
for (int i = 0; i < 360; i++) {
   //刻度線(xiàn)長(zhǎng)度為20，一圈是360度，并且秒針轉(zhuǎn)一圈為60秒，所以一秒就對(duì)應(yīng)360度/60秒=6度，那么五秒也就是5*6 = 30度
   if (i % 30 == 0) { //長(zhǎng)的
    canvas.drawLine(getWidth() / 3 - 25, 0, getWidth() / 3, 0, mPaint);
   } else if (i % 6 == 0) { //中的
    canvas.drawLine(getWidth() / 3 - 14, 0, getWidth() / 3, 0, mPaint);
   }
   //每繪制一次就旋轉(zhuǎn)1度，總共繪制了360條線(xiàn)
   canvas.rotate(1);
  }

canvas.save();
  for (int i = 0; i < 12; i++) {
   if (i == 0) {
    trans(canvas, 12 + "", i * 30, mPaint);
   } else {
    trans(canvas, i + "", i * 30, mPaint);
   }
  }
  canvas.restore();

//如果直接繪制數(shù)字的畫(huà)，文字也跟著旋轉(zhuǎn)了，數(shù)字有的就會(huì)倒著，所以執(zhí)行下面這一系列操作，再去繪制數(shù)字就正常了
 public void trans(Canvas canvas, String text, int degree, Paint paint) {
  Rect rect = new Rect();
  paint.getTextBounds(text, 0, text.length(), rect);
  //先將原來(lái)的坐標(biāo)軸旋轉(zhuǎn)30度
  canvas.rotate(degree);
  //將旋轉(zhuǎn)完成的坐標(biāo)軸平移到上方 它只是在y軸進(jìn)行的平移，所以x軸為0，y軸也就是圓心的位置減去35，35是自己固定的位置，可適當(dāng)自己修改；但是為負(fù)值，因?yàn)樵趛軸的上方，Android坐標(biāo)系往下為正數(shù)
  canvas.translate(0, -(getWidth() / 3 - 35));
  //這時(shí)在將原來(lái)旋轉(zhuǎn)的30都轉(zhuǎn)回去，此時(shí)的坐標(biāo)軸與開(kāi)始的坐標(biāo)軸都是直立的，只不過(guò)現(xiàn)在的位置處于原來(lái)坐標(biāo)軸的 右上方
  canvas.rotate(-degree);
  //開(kāi)始寫(xiě)文字 1，2，3，。。。。。12 因?yàn)槲淖謱?xiě)
  canvas.drawText(text, -rect.width() / 2, rect.height() / 2, paint);
  //寫(xiě)完文字后開(kāi)始將坐標(biāo)軸復(fù)原 先是順時(shí)針旋轉(zhuǎn)30都，
  canvas.rotate(degree);
  //再平移到圓心的位置
  canvas.translate(0, getWidth() / 3 - 35);
  //在逆時(shí)針平移30都
  canvas.rotate(-degree);
 }

//秒針
  canvas.save(); //save方法作用是將畫(huà)布先保存下來(lái)，為了不影響其他的元素，例如繪制兩張圖片，繪制完第一張接著繪制第二張，第二張可能就會(huì)受到第一張的影響，變形啊或者壓縮了
  mPaint.setColor(Color.RED);
  mPaint.setStyle(Paint.Style.STROKE);//繪制邊框
  mPaint.setStrokeWidth(2);//邊框?qū)挾?
  canvas.rotate(secondDegree);//這三個(gè)變量在下面代碼中
  canvas.drawLine(0, 0, 0, -100, mPaint);//豎直的，只在Y軸上，所以X軸都為0，100其實(shí)是指針的長(zhǎng)度，因?yàn)樵谏戏剑詾樨?fù)數(shù)
  canvas.restore();

  //分針
  canvas.save();
  mPaint.setColor(Color.BLACK);
  mPaint.setStyle(Paint.Style.STROKE);//繪制邊框
  mPaint.setStrokeWidth(4);//邊框?qū)挾?比指針粗點(diǎn)
  canvas.rotate(minuteDegree);
  canvas.drawLine(0, 0, 0, -80, mPaint);
  canvas.restore();

  //時(shí)針
  canvas.save();
  //mPaint.setColor(Color.GREEN);
  mPaint.setStyle(Paint.Style.STROKE);//繪制邊框
  mPaint.setStrokeWidth(6);//邊框?qū)挾?比指分針粗點(diǎn)
  canvas.rotate(hourDegree);
  canvas.drawLine(0, 0, 0, -60, mPaint);
  canvas.restore();

private float secondDegree;
private float minuteDegree;
private float hourDegree;
private Timer timer = new Timer();
private TimerTask timerTask = new TimerTask() {
  @Override
  public void run() {
   if (secondDegree == 360) {
    secondDegree = 0;
   }
   if (minuteDegree == 360) {
    minuteDegree = 0;
   }
   if (hourDegree == 360) {
    hourDegree = 0;
   }

   //這三個(gè)變量的換算方式，變量名起分針和秒針起反了，也無(wú)所謂了
   //第一個(gè)360/60=6，也就是一秒鐘走六度
   //第二個(gè)6/60 分針一秒針走0.1度
   //時(shí)針，一秒鐘走1/120度
   secondDegree = secondDegree + 6;
   minuteDegree = minuteDegree + 0.1f;
   hourDegree = hourDegree + 1 / 120f;
   /**
    * 自定義View 刷新界面有三種
    * 1：Invalidate() 如果只是內(nèi)容變動(dòng)，可使用此方法
    * 2：postInvalidate() 涉及到線(xiàn)程切換的
    * 3：requestLayout() view位置變動(dòng)，需要調(diào)用此方法 涉及到RadioGroup
    */
   postInvalidate();//涉及到線(xiàn)程，界面刷新需要使用此方法
  }
 };

 public void start() {
  timer.schedule(timerTask, 0, 1000);
 }

 //秒針
  canvas.save(); 
  mPaint.setColor(Color.RED);
  mPaint.setStyle(Paint.Style.STROKE);
  mPaint.setStrokeWidth(2);
  **canvas.rotate(secondDegree);**
  canvas.drawLine(0, 0, 0, -100, mPaint);
  canvas.restore();

  //分針
  canvas.save();
  mPaint.setColor(Color.BLACK);
  mPaint.setStyle(Paint.Style.STROKE);
  mPaint.setStrokeWidth(4);
  **canvas.rotate(minuteDegree);**
  canvas.drawLine(0, 0, 0, -80, mPaint);
  canvas.restore();

  //時(shí)針
  canvas.save();
  //mPaint.setColor(Color.GREEN);
  mPaint.setStyle(Paint.Style.STROKE);
  mPaint.setStrokeWidth(6);
  **canvas.rotate(hourDegree);**
  canvas.drawLine(0, 0, 0, -60, mPaint);
  canvas.restore();

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
 xmlns:tools="http://schemas.android.com/tools"
 android:layout_width="match_parent"
 android:layout_height="match_parent"
 tools:context="com.liuguijie.customwatch.MainActivity">
 <com.liuguijie.customwatch.Watch
  android:id="@+id/watch"
  android:layout_centerInParent="true"
  android:layout_width="300dp"
  android:layout_height="300dp" />
</RelativeLayout>

//調(diào)用start方法
Watch watchView = findViewById(R.id.watch);
watchView.start();