環(huán)形ProgressBar的進(jìn)度百分比顯示

要在環(huán)形ProgressBar上顯示進(jìn)度百分比，可以通過(guò)設(shè)置ProgressBar的樣式和自定義繪制來(lái)實(shí)現(xiàn)。以下是一個(gè)示例代碼，演示如何在環(huán)形ProgressBar上顯示進(jìn)度百分比：

public class CircleProgressBar extends View {

    private Paint mPaint;
    private RectF mRectF;
    private int mProgress;
    private int mMaxProgress;
    private String mProgressText;

    public CircleProgressBar(Context context) {
        super(context);
        init();
    }

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

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

    private void init() {
        mPaint = new Paint();
        mPaint.setAntiAlias(true);
        mPaint.setStyle(Paint.Style.STROKE);
        mPaint.setStrokeWidth(10);
        mRectF = new RectF();
        mMaxProgress = 100;
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);

        int centerX = getWidth() / 2;
        int centerY = getHeight() / 2;
        int radius = Math.min(centerX, centerY) - 5;

        mRectF.set(centerX - radius, centerY - radius, centerX + radius, centerY + radius);

        mPaint.setColor(Color.GRAY);
        canvas.drawCircle(centerX, centerY, radius, mPaint);

        mPaint.setColor(Color.BLUE);
        canvas.drawArc(mRectF, -90, 360 * mProgress / mMaxProgress, false, mPaint);

        mPaint.setTextSize(50);
        mProgressText = mProgress + "%";
        float textWidth = mPaint.measureText(mProgressText);
        canvas.drawText(mProgressText, centerX - textWidth / 2, centerY + mPaint.getTextSize() / 2, mPaint);
    }

    public void setProgress(int progress) {
        mProgress = progress;
        invalidate();
    }
}

在上面的代碼中，我們繼承了View類(lèi)，并重寫(xiě)了onDraw方法，通過(guò)繪制圓形和弧線來(lái)實(shí)現(xiàn)環(huán)形ProgressBar的效果。同時(shí)，在ProgressBar的中心繪制了進(jìn)度百分比的文本。

要在Activity中使用這個(gè)自定義的CircleProgressBar，可以像下面這樣：

CircleProgressBar progressBar = findViewById(R.id.circleProgressBar);
progressBar.setProgress(50); // 設(shè)置進(jìn)度為50%

通過(guò)調(diào)用setProgress方法，可以設(shè)置ProgressBar的進(jìn)度，進(jìn)度百分比將會(huì)顯示在環(huán)形ProgressBar的中心位置。