MainActivity:

public class MainActivity extends AppCompatActivity {
        private Button btnAdd;
        private ProgressView pv;

        private static final int FLAG = 0x123;

        private Handler handler = new Handler() {
            @Override
public void handleMessage(Message msg) {
                super
 
.handleMessage(msg);
                switch (msg.what) {
                    case FLAG:
                        int progress = pv.getProgress();
                        progress += 10;
                        if (progress > 100) {
                            progress = 0;
                        }
                        pv
 
.setProgress(progress);
                        handler.sendEmptyMessageDelayed(FLAG, 1000);
                        break;
                }
            }
        };

        @Override
protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main
 
);

            btnAdd = (Button) findViewById(R.id.btn_add);

            pv = (ProgressView) findViewById(R.id.pv_data);

            btnAdd.setOnClickListener(new View.OnClickListener() {
                @Override
public void onClick(View v) {
//                int progress = pv.getProgress();
//                progress += 30;
//                pv.setProgress(progress);
handler.sendEmptyMessageDelayed(FLAG, 1000);
                }
            });

            pv.setListener(new ProgressView.ProgressUpdateListener(){

                @Override
public void onProgressUpdated(int progress) {
                    if (progress >= 100) {
//                    handler.remove;
startActivity(new Intent(MainActivity.this, ScanActivity.class));

                    }
                }
            });
        }


        @Override
protected void onStop() {
            super.onStop();
            handler.removeMessages(FLAG);
        }
    }

自定義View:

public class ProgressView extends View {
    private ProgressUpdateListener listener;

    interface  ProgressUpdateListener {
        void onProgressUpdated(int progress);
    }

    public void setListener(ProgressUpdateListener listener) {
        this.listener = listener;
    }

    private 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);
    }

    public int getProgress() {
        return progress;
    }

    public void setProgress(int progress) {
        this.progress = progress;
        postInvalidate();
        if (listener != null) {
            listener.onProgressUpdated(progress);
        }
    }

    @Override
protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        int width = getWidth();
        int height = getHeight();

        // 繪圖範圍
int react = Math.min(width, height);

        // 半徑
int radius = react / 2;

        // 繪製最外層的大圓
Paint paint = new Paint(Paint.ANTI_ALIAS_FLAG);
        paint.setColor(Color.GREEN);
        paint.setStyle(Paint.Style.STROKE);

        canvas.drawCircle(radius, radius, radius, paint);


        paint.reset();
        paint.setStyle(Paint.Style.STROKE);
        paint.setStrokeWidth(20);
        paint.setColor(Color.RED);
        // 畫扇形
canvas.drawArc(10, 10, react-10, react-10, -90, progress*360/100, true, paint);

        // 畫內層的小圓
paint.reset();
        paint.setColor(Color.WHITE);
        paint.setStyle(Paint.Style.FILL_AND_STROKE);
        canvas.drawCircle(radius, radius, radius - 20, paint);


        // 畫進度文字
paint.reset();
        paint.setColor(Color.BLUE);
        paint.setTextSize(40);

        Rect rect = new Rect();
        paint.getTextBounds(progress + "", 0, String.valueOf(progress).length(),
                rect);
        int textWidth = rect.width();
        int textHeight = rect.height();

        canvas.drawText(progress + "", radius-textWidth/2, radius-textHeight/2, paint);
    }
}