简书链接:圆形进度条实现方案
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@Override
protected void onDraw(Canvas canvas) {
    super.onDraw(canvas);

    //画背景圆环
    int center = getWidth() / 2;

    float radius = center - roundWidth / 2;
    paint.setColor(roundColor);
    paint.setStyle(Paint.Style.STROKE);
    paint.setStrokeWidth(roundWidth); // 圆环的宽度
    paint.setAntiAlias(true);
    canvas.drawCircle(center,center,radius,paint);

    // 画进度百分比
    paint.setColor(textColor);
    paint.setStrokeWidth(0);
    paint.setTextSize(textSize);
    paint.setTypeface(Typeface.DEFAULT_BOLD);

    int percent = (int)(progress / (float)max * 100);
    String strPercent = percent + "%";
    Paint.FontMetricsInt fm = paint.getFontMetricsInt();
    if(percent != 0){
        canvas.drawText(strPercent, getWidth() / 2 - paint.measureText(strPercent) / 2 ,
                getWidth() / 2  +(fm.bottom - fm.top)/2 - fm.bottom, paint);
    }


    // 画圆弧
    RectF oval = new RectF(center - radius, center - radius,
            center + radius, center + radius);
    paint.setColor(roundProgressColor);
    paint.setStrokeWidth(roundWidth);
    paint.setStyle(Paint.Style.STROKE);
    paint.setStrokeCap(Paint.Cap.ROUND);
    canvas.drawArc(oval, 0 , 360 * progress / max, false, paint);

}

public void setProgress(int progress){
    if(progress < 0 ){
        throw new IllegalArgumentException("进度Progress不能小于0");
    }
    if(progress > max){
        progress = max;
    }
    if(progress <= max){
        this.progress = progress;
        postInvalidate();
    }
}