进度条

public class ProgressView extends View{
   private Handler handler=new Handler(){
        @Override
        public void handleMessage(Message msg) {
            super.handleMessage(msg);
            if(msg.what==0){
                progress++;
                if(progress<100){
                    //重新绘制
                    postInvalidate();
                    handler.sendEmptyMessageDelayed(0,10);
                }
                if(progress==100){
                    progress=0;
                    postInvalidate();
                }

            }
        }
    };
   int progress=0;
    public ProgressView(Context context) {
        super(context);
    }

    public ProgressView(Context context, @Nullable AttributeSet attrs) {
        super(context, attrs);
    }

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

    @RequiresApi(api = Build.VERSION_CODES.LOLLIPOP)
    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        Paint paint=new Paint();
        paint.setStyle(Paint.Style.STROKE);
        paint.setColor(Color.BLACK);
        paint.setStrokeWidth(2);
        canvas.drawCircle(getMeasuredWidth()/2,getMeasuredHeight()/2,getWidth()/2,paint);

        paint.setStyle(Paint.Style.STROKE);
        paint.setColor(Color.RED);
        RectF rectf=new RectF(0,0,getMeasuredWidth(),getMeasuredHeight());
        canvas.drawArc(rectf,0,360*progress/100,false,paint);
        String pro=progress+"%";
        Rect rect=new Rect();
        paint.getTextBounds(pro,0,pro.length(),rect);
        canvas.drawText(pro,getMeasuredWidth()/2-rect.width()/2,getMeasuredHeight()/2+rect.width()/2,paint);

    }
    public  void start(){
        handler.sendEmptyMessageDelayed(0,10);
    }

}

主方法：

        ProgressView progressView = findViewById(R.id.pv);
        progressView.start();