您的代码显示了它，这是创建矩形并添加矩形的方法：

PdfTemplate template = writer.getDirectContent().createTemplate(120, 80);
template.setColorFill(BaseColor.RED);
template.rectangle(0, 0, 120, 80);
template.fill();
writer.releaseTemplate(template);
table.addCell(Image.getInstance(template));

iTextPdfTemplate生成PDF表单XObject。XObject表单又是PDF内容流，它是对
图形对象（包括路径对象，文本对象和采样图像）的任何序列的独立描述
（ISO 32000-1的8.10.1节），即单独的图形
指令流，其内容可以从任何其他内容流中引用。

对于页面内容流，这
是包含表格XObject的行：

q 1.13 0 0 1.13 229.77 695.69 cm /Xf1 Do Q

（将变换矩阵拉伸到1.13并移动一点，
然后绘制XObject Xf1，然后重置变换矩阵。）

该XObject Xf1的内容流是这样的：

1 0 0 rg
0 0 120 80 re
f

即，它将不描边的颜色设置为RGB红色，在
原点定义一个120x80的矩形，并填充它。

这是我用来获取页面内容的行代码：

String pageContent = new String(reader.getPageContent(1));

该行不足以获取所有内容详细信息：

它仅返回即时页面内容，而不返回即时内容中使用的XObjects形式和模式的详细指令。人们经常会发现其直接页面内容仅引用一个或多个XObjects形式的PDF。

尽管有外观，但页面内容是二进制性质，而不是文本性质。一旦使用了非标准编码的字体，PDF字符串的内容在Java字符串中就毫无意义，或者（取决于您的标准编码）甚至中断了。

相反，应该使用iText解析器框架，例如：

ExtRenderListener extRenderListener = new ExtRenderListener()
{
    @Override
    public void beginTextBlock()                        {   }
    @Override
    public void renderText(TextRenderInfo renderInfo)   {   }
    @Override
    public void endTextBlock()                          {   }
    @Override
    public void renderImage(ImageRenderInfo renderInfo) {   }

    @Override
    public void modifyPath(PathConstructionRenderInfo renderInfo)
    {
        pathInfos.add(renderInfo);
    }

    @Override
    public Path renderPath(PathPaintingRenderInfo renderInfo)
    {
        GraphicsState graphicsState;
        try
        {
            graphicsState = getGraphicsState(renderInfo);
        }
        catch (NoSuchFieldException | SecurityException | IllegalArgumentException | IllegalAccessException e)
        {
            e.printStackTrace();
            return null;
        }

        Matrix ctm = graphicsState.getCtm();

        if ((renderInfo.getOperation() & PathPaintingRenderInfo.FILL) != 0)
        {
            System.out.printf("FILL (%s) ", toString(graphicsState.getFillColor()));
            if ((renderInfo.getOperation() & PathPaintingRenderInfo.STROKE) != 0)
                System.out.print("and ");
        }
        if ((renderInfo.getOperation() & PathPaintingRenderInfo.STROKE) != 0)
        {
            System.out.printf("STROKE (%s) ", toString(graphicsState.getStrokeColor()));
        }

        System.out.print("the path ");

        for (PathConstructionRenderInfo pathConstructionRenderInfo : pathInfos)
        {
            switch (pathConstructionRenderInfo.getOperation())
            {
            case PathConstructionRenderInfo.MOVETO:
                System.out.printf("move to %s ", transform(ctm, pathConstructionRenderInfo.getSegmentData()));
                break;
            case PathConstructionRenderInfo.CLOSE:
                System.out.printf("close %s ", transform(ctm, pathConstructionRenderInfo.getSegmentData()));
                break;
            case PathConstructionRenderInfo.CURVE_123:
                System.out.printf("curve123 %s ", transform(ctm, pathConstructionRenderInfo.getSegmentData()));
                break;
            case PathConstructionRenderInfo.CURVE_13:
                System.out.printf("curve13 %s ", transform(ctm, pathConstructionRenderInfo.getSegmentData()));
                break;
            case PathConstructionRenderInfo.CURVE_23:
                System.out.printf("curve23 %s ", transform(ctm, pathConstructionRenderInfo.getSegmentData()));
                break;
            case PathConstructionRenderInfo.LINETO:
                System.out.printf("line to %s ", transform(ctm, pathConstructionRenderInfo.getSegmentData()));
                break;
            case PathConstructionRenderInfo.RECT:
                System.out.printf("rectangle %s ", transform(ctm, expandRectangleCoordinates(pathConstructionRenderInfo.getSegmentData())));
                break;
            }
        }
        System.out.println();

        pathInfos.clear();
        return null;
    }

    @Override
    public void clipPath(int rule)
    {
    }

    List<Float> transform(Matrix ctm, List<Float> coordinates)
    {
        List<Float> result = new ArrayList<>();
        for (int i = 0; i + 1 < coordinates.size(); i += 2)
        {
            Vector vector = new Vector(coordinates.get(i), coordinates.get(i + 1), 1);
            vector = vector.cross(ctm);
            result.add(vector.get(Vector.I1));
            result.add(vector.get(Vector.I2));
        }
        return result;
    }

    List<Float> expandRectangleCoordinates(List<Float> rectangle)
    {
        if (rectangle.size() < 4)
            return Collections.emptyList();
        return Arrays.asList(
                rectangle.get(0), rectangle.get(1),
                rectangle.get(0) + rectangle.get(2), rectangle.get(1),
                rectangle.get(0) + rectangle.get(2), rectangle.get(1) + rectangle.get(3),
                rectangle.get(0), rectangle.get(1) + rectangle.get(3)
                );
    }

    String toString(BaseColor baseColor)
    {
        if (baseColor == null)
            return "DEFAULT";
        return String.format("%s,%s,%s", baseColor.getRed(), baseColor.getGreen(), baseColor.getBlue());
    }

    GraphicsState getGraphicsState(PathPaintingRenderInfo renderInfo) throws NoSuchFieldException, SecurityException, IllegalArgumentException, IllegalAccessException
    {
        Field gsField = PathPaintingRenderInfo.class.getDeclaredField("gs");
        gsField.setAccessible(true);
        return (GraphicsState) gsField.get(renderInfo);
    }

    final List<PathConstructionRenderInfo> pathInfos = new ArrayList<>();
};

try (   InputStream resource = [RETRIEVE FILE TO PARSE AS INPUT STREAM])
{
    PdfReader pdfReader = new PdfReader(resource);

    for (int page = 1; page <= pdfReader.getNumberOfPages(); page++)
    {
        System.out.printf("\nPage %s\n====\n", page);

        PdfReaderContentParser parser = new PdfReaderContentParser(pdfReader);
        parser.processContent(page, extRenderListener);

    }
}

(ExtractPaths
test method testExtractFromTestCreation)

For your sample file this results in the output

Page 1
====
STROKE (0,0,0) the path rectangle [88.3, 693.69, 227.77, 693.69, 227.77, 788.0, 88.3, 788.0] 
STROKE (0,0,0) the path rectangle [227.77, 693.69, 367.24, 693.69, 367.24, 788.0, 227.77, 788.0] 
STROKE (0,0,0) the path rectangle [367.23, 693.69, 506.7, 693.69, 506.7, 788.0, 367.23, 788.0] 
FILL (255,0,0) the path rectangle [229.77, 695.69, 365.37, 695.69, 365.37, 786.09, 229.77, 786.09] 
STROKE (DEFAULT) the path move to [228.0, 810.0] line to [338.0, 810.0]

iText将颜色值表示为字节（0-255），而不是
PDF使用的单位范围（0.0-1.0）。因此，您看到“（255,0,0）”，其中PDF选择了“ 1
0 0 rg”。