pdfbox. how to fetch fields of all kind of pdf forms

Question

I am able to fetch the field names for most of the pdf files using pdfbox but i am not able to fetch fields income taxform. is it something restricted in that form.

though it contains multiple fields in the form, it is showing only one field.

This is the output:

topmostSubform[0].

my code:

PDDocumentCatalog docCatalog = pdfDocument.getDocumentCatalog();
PDAcroForm acroForm = docCatalog.getAcroForm();
List fields = acroForm.getFields();

@SuppressWarnings("rawtypes")
java.util.Iterator fieldsIter = fields.iterator();
System.out.println(new Integer(fields.size()).toString());
while( fieldsIter.hasNext())
{
    PDField field = (PDField)fieldsIter.next();
    System.out.println(field.getFullyQualifiedName());
    System.out.println(field.getPartialName());
}

used in

public static void main(String[] args) throws IOException {
    PDDocument pdDoc = null;
    try {
        pdDoc = PDDocument.load("income.pdf");
    } catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace(); 
    }
    Ggdfgdgdgf feilds = new Ggdfgdgdgf();
    feilds.printFields(pdDoc);
}

Answer 1

The PDF in question is a hybrid AcroForm/XFA form. This means that it contains the form definition both in AcroForm and in XFA format.

PDFBox primarily supports AcroForm (which is the PDF form technology presented in the PDF specification), but as both formats are present, PDFBox can at least inspect the AcroForm form definition.

Your code ignores that AcroForm.getFields() does not return all field definitions but merely the definitions of the root fields, cf. the JavaDoc comments:

/**
 * This will return all of the documents root fields.
 * 
 * A field might have children that are fields (non-terminal field) or does not
 * have children which are fields (terminal fields).
 * 
 * The fields within an AcroForm are organized in a tree structure. The documents root fields 
 * might either be terminal fields, non-terminal fields or a mixture of both. Non-terminal fields
 * mark branches which contents can be retrieved using {@link PDNonTerminalField#getChildren()}.
 * 
 * @return A list of the documents root fields.
 * 
 */
public List<PDField> getFields()

If you want to access all fields, you have to walk the form field tree, e.g. like this:

public void test() throws IOException
{
    try (   InputStream resource = getClass().getResourceAsStream("f2290.pdf"))
    {
        PDDocument pdfDocument = PDDocument.load(resource);
        PDDocumentCatalog docCatalog = pdfDocument.getDocumentCatalog();
        PDAcroForm acroForm = docCatalog.getAcroForm();
        List<PDField> fields = acroForm.getFields();
        for (PDField field : fields)
        {
            list(field);
        }
    }
}

void list(PDField field)
{
    System.out.println(field.getFullyQualifiedName());
    System.out.println(field.getPartialName());
    if (field instanceof PDNonTerminalField)
    {
        PDNonTerminalField nonTerminalField = (PDNonTerminalField) field;
        for (PDField child : nonTerminalField.getChildren())
        {
            list(child);
        }
    }
}

This returns a huge list of fields for your document.

PS: You have not stated which PDFBox version you use. As currently PDFBox development clearly has begun recommending the use of the current 2.0.0 release candidates, I assumed in my answer that you use that version.

Answer 2

This can be done a lot easier using fieldTree

fun getFieldsInDocument(file: File): List<String> {
    return PDDocument.load(file).use { document ->
        document.documentCatalog.acroForm.fieldTree
                .filter { it is PDTerminalField }
                .map { field ->
                    field.fullyQualifiedName
                }
    }
}

This is Kotlin but in Java it looks basically the same.

Answer 3

Here is the sample code for reading a pdf.Before use it, set your input PDF file.

import java.io.File;
import java.io.FileInputStream;
import java.io.PrintWriter;
import org.apache.pdfbox.cos.COSDocument;
import org.apache.pdfbox.pdfparser.PDFParser;
import org.apache.pdfbox.pdmodel.PDDocument;
import org.apache.pdfbox.util.PDFTextStripper;

public class JavaApplication14 {

    PDFParser parser;
    String parsedText;
    PDFTextStripper pdfStripper;
    PDDocument pdDoc;
    COSDocument cosDoc;
//    PDDocumentInformation pdDocInfo;
// PDFTextParser Constructor 
    public JavaApplication14() {
    }
// Extract text from PDF Document
    String pdftoText(String fileName) {
        System.out.println("Parsing text from PDF file " + fileName + "....");
        File f = new File(fileName);
        if (!f.isFile()) {
            System.out.println("File " + fileName + " does not exist.");
            return null;
        }
        try {
            parser = new PDFParser(new FileInputStream(f));
        } catch (Exception e) {
            System.out.println("Unable to open PDF Parser.");
            return null;
        }
        try {
            parser.parse();
            cosDoc = parser.getDocument();
            pdfStripper = new PDFTextStripper();
            pdDoc = new PDDocument(cosDoc);
            parsedText = pdfStripper.getText(pdDoc);
        } catch (Exception e) {
            System.out.println("An exception occured in parsing the PDF Document.");
            e.printStackTrace();
            try {
                if (cosDoc != null) {
                    cosDoc.close();
                }
                if (pdDoc != null) {
                    pdDoc.close();
                }
            } catch (Exception e1) {
                e.printStackTrace();
            }
            return null;
        }
        System.out.println("Done.");
        return parsedText;
    }
// Write the parsed text from PDF to a file
    void writeTexttoFile(String pdfText, String fileName) {
        System.out.println("\nWriting PDF text to output text file " + fileName + "....");
        try {
            PrintWriter pw = new PrintWriter(fileName);
            pw.print(pdfText);
            pw.close();
        } catch (Exception e) {
            System.out.println("An exception occured in writing the pdf text to file.");
            e.printStackTrace();
        }
        System.out.println("Done.");
    }

    public static void main(String args[]) {
        String fileList[] = {"E:\\JavaApplication14\\src\\javaapplication14\\issues.pdf", "E:\\JavaApplication14\\src\\javaapplication14\\newTextDocument.txt"};
        if (fileList.length != 2) {
            System.out.println("Usage: java PDFTextParser <InputPDFFilename> <OutputTextFile>");
            System.exit(1);
        }
        JavaApplication14 pdfTextParserObj = new JavaApplication14();
        String pdfToText = pdfTextParserObj.pdftoText(fileList[0]);
        if (pdfToText == null) {
            System.out.println("PDF to Text Conversion failed.");
        } else {
            System.out.println("\nThe text parsed from the PDF Document....\n" + pdfToText);
            pdfTextParserObj.writeTexttoFile(pdfToText, fileList[1]);
        }
    }
}