如何使用POI绘制圆(而不是椭圆)

我试着在excel中的一个单元格上画一个圆(而不是椭圆),但总是得到一个椭圆。 我想要什么: enter image description here 我得到的: enter image description here

这是代码:

    Workbook workbook = new XSSFWorkbook();
        Sheet sheet = workbook.createSheet("Sheet1");
        Drawing<?> drawing = sheet.createDrawingPatriarch();
        XSSFClientAnchor anchor = new XSSFClientAnchor();
        anchor.setAnchorType(ClientAnchor.AnchorType.DONT_MOVE_AND_RESIZE);
        anchor.setCol1(0);
        anchor.setCol2(1);
        anchor.setRow1(0);
        anchor.setRow2(1);
        
        // here I set the size of the circle, making its diameter in x-axis equals to diameter y-axis, but didn't work.  
        // anchor.setDx1(0);
        // anchor.setDx2(255);
        // anchor.setDy1(0);
        // anchor.setDy2(255);

        XSSFSimpleShape circle = ((XSSFDrawing) drawing).createSimpleShape(anchor);
        circle.setShapeType(ShapeTypes.ELLIPSE);
        CTShape ctShape = circle.getCTShape();
        
        // change an ellipse into a circle
        CTShapeProperties spProps = ctShape.getSpPr();
        if (spProps == null) {
            spProps = ctShape.addNewSpPr();
        }
        CTTransform2D xfrm = spProps.isSetXfrm() ? spProps.getXfrm() : spProps.addNewXfrm();
        CTPositiveSize2D ext = xfrm.isSetExt() ? xfrm.getExt() : xfrm.addNewExt();
        long length = Units.toEMU(0.5 * 914400 / 2);
        ext.setCx(length);
        ext.setCy(length);

        // set color
        CTSolidColorFillProperties fillProps = spProps.isSetSolidFill() ? spProps.getSolidFill() : spProps.addNewSolidFill();
        fillProps.addNewSrgbClr().setVal(new byte[] { (byte) 0xFF, 0x00, 0x00 });
        
        workbook.write(new FileOutputStream("example.xlsx"));
        workbook.close();