我正在使用以下代码:https://www.tutorialspoint.com/pdfbox/pdfbox_inserting_image.htm
为帮助我将图像添加到现有的PDF中。问题是它创建的文件是空白页,上面只有图像。
这是我的代码:
public void signPDF(PdfDTO pdfDTO) throws IOException{
//Loading an existing document
File file = new File(getAbsolutePdfPath(pdfDTO));
PDDocument doc = PDDocument.load(file);
//Retrieving the page
PDPage page = doc.getPage(0);
//a test to ensure the doc is loading correctly
PDDocument testDoc = new PDDocument();
testDoc.addPage(page);
testDoc.save("C:" + File.separator + "Users" + File.separator + "kdotson" + File.separator + "Documents" + File.separator + "test.pdf");
testDoc.close(); //this file is good so I know the doc is loading correctly
//Creating PDImageXObject object
PDImageXObject pdImage = PDImageXObject.createFromFile("C://test_images/signature.pdf", doc);
//creating the PDPageContentStream object
PDPageContentStream contents = new PDPageContentStream(doc, page);
//Drawing the image in the PDF document
contents.drawImage(pdImage, 0, 0);
//Closing the PDPageContentStream object
contents.close();
//Saving the document
doc.save(new File(getSignedPdfLocation(pdfDTO))); //the created file has the image on it, so I know the image is loading correctly
//Closing the document
doc.close();
}
据我所知,我在做什么应该行得通,而且我没有收到任何错误,那怎么办?
答案 0 :(得分:1)
也请查看您尝试使用的JavaDocs和库的源代码。您创建一个PDPageContentStream
:
PDPageContentStream contents = new PDPageContentStream(doc, page);
该导体被记录为覆盖此页面的所有现有内容流:
/**
* Create a new PDPage content stream. This constructor overwrites all existing content streams
* of this page.
*
* @param document The document the page is part of.
* @param sourcePage The page to write the contents to.
* @throws IOException If there is an error writing to the page contents.
*/
public PDPageContentStream(PDDocument document, PDPage sourcePage) throws IOException
因此,您必须使用其他保留当前页面内容的构造函数,例如
/**
* Create a new PDPage content stream.
*
* @param document The document the page is part of.
* @param sourcePage The page to write the contents to.
* @param appendContent Indicates whether content will be overwritten, appended or prepended.
* @param compress Tell if the content stream should compress the page contents.
* @param resetContext Tell if the graphic context should be reset. This is only relevant when
* the appendContent parameter is set to {@link AppendMode#APPEND}. You should use this when
* appending to an existing stream, because the existing stream may have changed graphic
* properties (e.g. scaling, rotation).
* @throws IOException If there is an error writing to the page contents.
*/
public PDPageContentStream(PDDocument document, PDPage sourcePage, AppendMode appendContent,
boolean compress, boolean resetContext) throws IOException
因此
PDPageContentStream contents = new PDPageContentStream(doc, page, AppendMode.APPEND, true, true);
应该使您的代码按需工作。
或者,如果要将图像放在背景中,请尝试
PDPageContentStream contents = new PDPageContentStream(doc, page, AppendMode.PREPEND, true, true);
但是请注意,在某些情况下,图片在背景中是不可见的,例如如果现有内容以将整个页面区域填充为白色的指令开头。在这种情况下,必须在现有内容之上以某种透明度应用水印。