盡量簡(jiǎn)化的自定義viewgroup，為了方便看

public class SizeViewGroup extends ViewGroup {
public SizeViewGroup(Context context) {
this(context,null);
}

public SizeViewGroup(Context context, AttributeSet attrs) {
    super(context, attrs);

    TextView textView = new TextView(context) ;
    textView.setText("我是中國(guó)人");
    textView.setTextSize(100);
    textView.setBackgroundColor(Color.YELLOW);
    LayoutParams layoutParams = new LayoutParams(200,200);
    addView(textView,layoutParams);
    setBackgroundColor(Color.alpha(255));

}

@Override
protected void onLayout(boolean changed, int l, int t, int r, int b) {
    View textView = getChildAt(0) ;
    textView.layout(50,50,textView.getMeasuredWidth()+50,
            textView.getMeasuredHeight()+50);

}

@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
    super.onMeasure(widthMeasureSpec, heightMeasureSpec);
    //先測(cè)量所有子組件的大小
    measureChildren(widthMeasureSpec,heightMeasureSpec);
    //測(cè)量自身的大小，
    setMeasuredDimension(500,500);
}

@Override
protected void onDraw(Canvas canvas) {
    RectF rectF = new RectF(0,0,getMeasuredWidth(),getMeasuredHeight()) ;
    rectF.inset(2,2);
    Paint paint = new Paint(Paint.ANTI_ALIAS_FLAG) ;
    paint.setStyle(Paint.Style.STROKE);
    paint.setStrokeWidth(2);
    paint.setColor(Color.RED);
    Path path = new Path() ;
    path.addRoundRect(rectF,20,20, Path.Direction.CCW);
    canvas.drawPath(path,paint);
    super.onDraw(canvas);
}

}