private int mHeight, mWidth;//寬高
  private Paint mPaint;//扇形的畫筆
  private Paint mTextPaint;//畫文字的畫筆

  private int centerX, centerY;//中心坐標

  //"其他"的value
  //扇形圖分成太多快 所以要合并一部分為其他 即圖中灰色部分
  private double rest;

  private int maxNum = 5;//扇形圖的最大塊數 超過的item就合并到其他

  String others = "其他";//“其他”塊要顯示的文字
  double total;//數據的總和 
  double[] datas;//數據集
  String[] texts;//每個數據對應的文字集

  //顏色 默認的顏色
  private int[] mColors = {
      Color.parseColor("#FF4081"), Color.parseColor("#ffc0cb"),
      Color.parseColor("#00ff00"), Color.parseColor("#0066ff"), Color.parseColor("#ffee00")
  };

  private int mTextSize;//文字大小 單位：像素

  private int radius = 1000;//半徑 在畫圖時初始化

  @Override
  protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
    super.onMeasure(widthMeasureSpec, heightMeasureSpec);

    //獲取寬高 不要設置wrap_content
    mHeight = MeasureSpec.getSize(heightMeasureSpec);
    mWidth = MeasureSpec.getSize(widthMeasureSpec);

  }

@Override
protected void onDraw(Canvas canvas) {
  super.onDraw(canvas);
  //無數據 直接返回
  if (datas == null || datas.length == 0) return;

  centerX = (getRight() - getLeft()) / 2;
  centerY = (getBottom() - getTop()) / 2;
  int min = mHeight > mWidth ? mWidth : mHeight;
  if (radius > min / 2) {
    radius = (int) ((min - getPaddingTop() - getPaddingBottom()) / 3.5);
  }

  //畫各個扇形
  drawCircle(canvas);

  //畫線與文字
  drawLineAndText(canvas);

}

  //畫扇形
  private void drawCircle(Canvas canvas) {
    int centerX =( getRight() - getLeft() )/2;//中點
    int centerY = ( getBottom() - getTop()) /2;
    RectF rect = new RectF((float) (centerX - radius), centerY-radius,
        centerX+radius,centerY+radius);//圓形區域

    int start = 0;//扇形開始的角度
    for (int i = 0; i < (maxNum<datas.length?maxNum:datas.length); i++) {
      float angles = (float) ((datas[i] * 1.0f /total) * 360);//計算扇形的角度
      mPaint.setColor(mColors[i%mColors.length]);//顏色
      canvas.drawArc(rect,start,angles,true,mPaint);//畫扇形
      start += angles;//下一個扇形開始的角度
    }

    //畫"其他"部分 即圖中灰色的部分
    rest =0;//保存其他部分的value
    for(int i=maxNum;i<datas.length;i++){
      rest+=datas[i];
    }
    float angles = (float) 360 - start;//角度
    mPaint.setColor(Color.GRAY);
    canvas.drawArc(rect,start,angles,true,mPaint);

  }

//畫線與文字
  private void drawLineAndText(Canvas canvas) {
    int start = 0;
    //平移畫布到中心 所以下面的坐標是從中點開始算起的
    canvas.translate(centerX, centerY);
    mPaint.setStrokeWidth(4);//線條寬度

    //如果數據集過大 那么要合并到其他
    for (int i = 0; i < (maxNum < datas.length ? maxNum : datas.length); i++) {
      float angles = (float) ((datas[i] * 1.0f / total) * 360);
      //畫線條和文字
      drawLine(canvas, start, angles, texts[i], mColors[i % mColors.length]);
      start += angles;
    }
    //畫其他部分的線條和文字
    if (start < 360)//如果start小于360 說明有其他部分
      drawLine(canvas, start, 360 - start, others, Color.GRAY);

  }

  private void drawLine(Canvas canvas, int start, float angles, String text, int color) {
    mPaint.setColor(color);
    float stopX, stopY;
    stopX = (float) ((radius + 40) * Math.cos((2 * start + angles) / 2 * Math.PI / 180));
    stopY = (float) ((radius + 40) * Math.sin((2 * start + angles) / 2 * Math.PI / 180));

    canvas.drawLine((float) ((radius - 20) * Math.cos((2 * start + angles) / 2 * Math.PI / 180)),
        (float) ((radius - 20) * Math.sin((2 * start + angles) / 2 * Math.PI / 180)),
        stopX, stopY, mPaint
    );
    //畫橫線
    int dx;//判斷橫線是畫在左邊還是右邊
    int endX;
    if (stopX > 0) {
      endX = (centerX - getPaddingRight() - 20);
    } else {
      endX = (-centerX + getPaddingLeft() + 20);
    }
    //畫橫線
    canvas.drawLine(stopX, stopY,
        endX, stopY, mPaint
    );
    dx = (int) (endX - stopX);

    //測量文字大小
    Rect rect = new Rect();
    mTextPaint.getTextBounds(text, 0, text.length(), rect);
    int w = rect.width();
    int h = rect.height();
    int offset = 20;//文字在橫線的偏移量
    //畫文字 文字的Y坐標值的是文字底部的Y坐標
    canvas.drawText(text, 0, text.length(), dx > 0 ? stopX + offset : stopX - w - offset, stopY + h, mTextPaint);

    //測量百分比大小
    String percentage = angles / 3.60 + "";
    percentage = percentage.substring(0, percentage.length() > 4 ? 4 : percentage.length()) + "%";
    mTextPaint.getTextBounds(percentage, 0, percentage.length(), rect);
    w = rect.width() - 10;
    //畫百分比
    canvas.drawText(percentage, 0, percentage.length(), dx > 0 ? stopX + offset : stopX - w - offset, stopY - 5, mTextPaint);

  }

  public abstract class ArcViewAdapter<T> {

    public void setData(List<T> list) {
      datas = new double[list.size()];
      texts = new String[list.size()];
      for (int i = 0; i < list.size(); i++) {
        total += getValue(list.get(i));
        datas[i] = getValue(list.get(i));
        texts[i] = getText(list.get(i));
      }
      invalidate();//請求重繪
    }

    //通過傳來的數據集的某個元素 得到具體的數字
    public abstract double getValue(T t);

    //通過傳來的數據集的某個元素 得到具體的描述
    public abstract String getText(T t);
  }

ArcView arcView = (ArcView) findViewById(R.id.arc);
    List<Times> times = new ArrayList<>();
    for (int i = 6; i > 0; i--) {
      Times t = new Times();//這個類就只有兩個變量
      t.hour = i;
      t.text = "Number"+i;
      times.add(t);
    }

    //初始化適配器
    ArcView.ArcViewAdapter myAdapter = arcView.new ArcViewAdapter<Times>(){
      @Override
      public double getValue(Times times) {
        return times.hour;
      }

      @Override
      public String getText(Times times) {
        return times.text;
      }
    };
    myAdapter.setData(times);//綁定數據