将2 pdf与itextsharp压模合并

Question

I want to take 2 pdf files and merge them together.

each file is one page long. the reason to merge them is that one file is simply a footer. The footer needs to be attached to the existing file.

I'm using a stamper to try and merge the 2 files.

I successfully create the output file, but it doesn't have the footer. It's just a copy of the original input file. Any idea why they aren't merging?

using (Stream inputPdfStream = new FileStream(inputFile, FileMode.Open, FileAccess.Read, FileShare.Read))
using (Stream inputPdfFooterStream = new FileStream(footerPdf, FileMode.Open, FileAccess.Read, FileShare.Read))
using (Stream outputPdfStream = new FileStream(outputFile, FileMode.Create, FileAccess.Write, FileShare.None))
{
    var reader = new PdfReader(inputPdfStream);
    var stamper = new PdfStamper(reader, outputPdfStream);
    var pdfContentByte = stamper.GetOverContent(1);
    stamper.FormFlattening = true;
    stamper.Close();
}

Answer 1

There are different problems with your question.

Problem #1: why did you add the line stamper.FormFlattening = true; ? Are you working with a form? I don't see you do anything with forms, so why would you flatten the document?

Problem #2: You say you want to merge two documents with PdfStamper . That is misleading. Merging documents is done with PdfCopy . From your explanation, I gather that you want to superimpose two documents. You are right that you need PdfStamper to do so.

Problem #3: You want to use a specific document containing a footer as company stationery. In that case, you want to add the content of the stationery under the actual content. Then why are you using stamper.GetOverContent(1); ? Use stamper.GetUnderContent(1); instead.

Problem #4: You are creating an inputPdfFooterStream to read the document with the footer, but I don't see you using that stream anywhere. What do you expect?

Problem #5: You didn't read the documentation. This is your main problem. Download chapter 6 of my book (it's available for free, and I've been referring to it in dozens of answers on StackOverflow). Go to page 176 where it says "Adding company stationery to an existing document". That example meets your requirement completely!

// Create readers
PdfReader reader = new PdfReader(src);
PdfReader s_reader = new PdfReader(stationery);
using (MemoryStream ms = new MemoryStream()) {
  // Create the stamper
  using (PdfStamper stamper = new PdfStamper(reader, ms)) {
    // Add the stationery to each page
    PdfImportedPage page = stamper.GetImportedPage(s_reader, 1);
    int n = reader.NumberOfPages;
    PdfContentByte background;
    for (int i = 1; i <= n; i++) {
      background = stamper.GetUnderContent(i);
      background.AddTemplate(page, 0, 0);
    }
  } 
  return ms.ToArray();   
}

In your code, you only have one reader. In my code, I also have an object called s_reader that takes the footerPdf document and allows you to created a PdfImportedPage :

PdfImportedPage page = stamper.GetImportedPage(s_reader, 1);

This page is then added under the existing content of the actual document:

background = stamper.GetUnderContent(i);
background.AddTemplate(page, 0, 0);

Note that this example assumes that both documents have the same page size and that the origin of the coordinate system of the document with the actual content coincided with the lower-left corner. If that isn't the case with your PDFs, you can have a situation where the footer isn't visible or is only partly visible. Also: if the document with the actual content is opaque, it will also make the footer invisible.