您可以通过将此方法添加到this old answer的PdfContentStreamEditor类来编辑表单XObjects内容流：

public void processFormXObject(PDFormXObject formXObject, PDPage page) throws IOException {
    PDStream stream = new PDStream(document);
    replacement = new ContentStreamWriter(replacementStream = stream.createOutputStream(COSName.FLATE_DECODE));
    super.processChildStream(formXObject, page);
    replacementStream.close();
    try (OutputStream outputStream = formXObject.getCOSObject().createOutputStream()) {
        stream.createInputStream().transferTo(outputStream);
    } finally {
        replacement = null;
        replacementStream = null;
    }
}

字符串
（PdfContentStreamEditor方法）
(Form XObject的内容流并不在Contents子条目中，它们本身就是内容流。因此，替换流内容必须以不同的方式存储。）
你可以这样使用它：

PDDocument document = ...;
for (PDPage page : document.getDocumentCatalog().getPages()) {
    PdfContentStreamEditor editor = new PdfContentStreamEditor(document, page) {
        @Override
        protected void write(ContentStreamWriter contentStreamWriter, Operator operator, List<COSBase> operands) throws IOException {
            String operatorString = operator.getName();

            if (RGB_FILL_COLOR_OPERATORS.contains(operatorString))
            {
                for (int i = 0; i < operands.size(); i++) {
                    COSBase number = operands.get(i);
                    if (number instanceof COSNumber) {
                        operands.set(i, new COSFloat(1.0f - ((COSNumber)number).floatValue()));
                    }
                }
            }

            super.write(contentStreamWriter, operator, operands);
        }

        final List<String> RGB_FILL_COLOR_OPERATORS = Arrays.asList("rg", "sc", "scn");
    };
    PDResources resources = page.getResources();
    for (COSName name : resources.getXObjectNames()) {
        PDXObject xObject = resources.getXObject(name);
        if (xObject instanceof PDFormXObject) {
            System.out.printf("Editing form XObject %s.\n", name.toString());
            editor.processFormXObject((PDFormXObject) xObject, page);
        }
    }
}

型

• （EditFormXObjectContent测试testInvertColorsHighPioneerFallNewsletterADApdf_2）*

此示例反转文档的直接表单XObject页面资源中的某些填充颜色。