finding out required fields to fill in pdf file

问题:

I'm starting with new functionality in my android application which will help to fill certain PDF forms.

I find out that the best solution will be to use iText library.

I can read file, and read AcroFields from document but is there any possibility to find out that specific field is marked as required?

I tried to find this option in API documentation and on Internet but there were nothing which can help to solve this issue.

回答1:

Please take a look at section 13.3.4 of my book, entitled "AcroForms revisited". Listing 13.15 shows a code snippet from the InspectForm example that checks whether or not a field is a password or a multi-line field.

With some minor changes, you can adapt that example to check for required fields:

for (Map.Entry<String,AcroFields.Item> entry : fields.entrySet()) {
    out.write(entry.getKey());
    item = entry.getValue();
    dict = item.getMerged(0);
    flags = dict.getAsNumber(PdfName.FF);
    if (flags != null && (flags.intValue() & BaseField.REQUIRED) > 0)
        out.write(" -> required\n");
}

回答2:

check required fields without looping for itext5.

        String src = "yourpath/pdf1.pdf";
        String dest = "yourpath/pdf2.pdf";

        PdfReader reader = new PdfReader(src);
        PdfStamper stamper = new PdfStamper(this.reader, new FileOutputStream(dest));

        AcroFields form = this.stamper.getAcroFields();
        Map<String,AcroFields.Item> fields = form.getFields();
        AcroFields.Item item;
        PdfDictionary dict;
        PdfNumber flags;
        item=fields.get("fieldName");
        dict = item.getMerged(0);
        flags = dict.getAsNumber(PdfName.FF);
        if (flags != null && (flags.intValue() & BaseField.REQUIRED) > 0) 
        {
                System.out.println("flag  has set");
        }