iText Android - 给现有的PDF添加文字

Question

我们有一份PDF文件，其中包含一些字段以收集数据，我需要通过iText在Android上编程方式填充这些位置中的一些文本。我一直在考虑不同的方法来实现这一目标，但每种方法都没有取得太大成功。

注意：我使用的是iText的Android版本（iTextG 5.5.4），并且大多数测试是在三星Galaxy Note 10.1 2014（Android 4.4）上进行的。

• The approach I took from the start was to "draw" the text on a given coordinates, for a given page. This has some problems with the management of the fields (I have to be aware of the length of the strings, and it could be hard to position each text in the exact coordinate of the pdf). But most importantly, the performance of the process is really slow in some devices/OSVersions (it works great in Nexus 5 with 5.0.2, but takes several minutes with a 5MB Pdf on the Note 10.1).

      pdfReader = new PdfReader(is);
  
      document = new Document();
  
      ByteArrayOutputStream baos = new ByteArrayOutputStream();
      pdfCopy = new PdfCopy(document, baos);
      document.open();
  
      PdfImportedPage page;
      PdfCopy.PageStamp stamp;
  
      for (int i = 1; i <= pdfReader.getNumberOfPages(); i++) {
  
          page = pdfCopy.getImportedPage(pdfReader, i); // First page = 1
          stamp = pdfCopy.createPageStamp(page);
  
          for (int i=0; i<10; i++) {
              int posX = i*50;
              int posY = i*100;
              Phrase phrase = new Phrase("Example text", FontFactory.getFont(FontFactory.HELVETICA, 12, BaseColor.RED));
              ColumnText.showTextAligned(stamp.getOverContent(), Element.ALIGN_CENTER, phrase, posX, posY, 0);
          }
  
          stamp.alterContents();
          pdfCopy.addPage(page);
      }
  

• We though about adding "forms fields" instead of drawing. That way I can configure a TextField and avoid managing the texts myself. However, the final PDF shouldn't have any annotations, so I would need to copy it into a new Pdf without annotations and with those "forms fields" drawn. I don't have an example of this because I wasn't able to perform this, I don't even know if this is possible/worthwhile.

• The third option would be to receive a Pdf with the "forms fields" already added, that way I only have to fill them. However I still need to create a new Pdf with all those fields and without annotations...

我希望了解在性能方面完成此过程的最佳方法，以及有关如何实现它的任何帮助。我对iText非常陌生，任何帮助将不胜感激。

谢谢！

编辑

最终我使用了第三种选择：具有可编辑字段的PDF文件，我们填充之后使用“平铺”创建一个不可编辑的PDF文件，并且所有文本都已经存在其中。

代码如下：

    pdfReader = new PdfReader(is);

    FileOutputStream fios = new FileOutputStream(outPdf);

    PdfStamper pdfStamper = new PdfStamper(pdfReader, fios);
    //Filling the PDF (It's totally necessary that the PDF has Form fields)
    fillPDF(pdfStamper);
    //Setting the PDF to uneditable format
    pdfStamper.setFormFlattening(true);

    pdfStamper.close();

以及填写表单的方法：

public static void fillPDF(PdfStamper stamper) throws IOException, DocumentException{
    //Getting the Form fields from the PDF
    AcroFields form = stamper.getAcroFields();
    Set<String> fields = form.getFields().keySet();
    for(String field : fields){
            form.setField("name", "Ernesto");
            form.setField("surname", "Lage");
        }
    }
}

这种方法的唯一缺点是您需要知道每个字段的名称才能填写它。

- Koesh

Answer 1

在iText中有一个名为“flattening”的过程，它会获取表单字段并用字段包含的文本替换它们。

我已经好几年没有使用过iText（也没有在Android上使用过），但是如果您在手册或在线示例中搜索“flattening”，您应该可以找到如何执行此操作的方法。

- GreyBeardedGeek