Replacing PDF objects

JAVA

/*
    This file is part of the iText (R) project.
    Copyright (c) 1998-2023 Apryse Group NV
    Authors: Apryse Software.

    For more information, please contact iText Software at this address:
    sales@itextpdf.com
 */
package com.itextpdf.samples.sandbox.stamper;

import com.itextpdf.kernel.pdf.PdfDictionary;
import com.itextpdf.kernel.pdf.PdfDocument;
import com.itextpdf.kernel.pdf.PdfName;
import com.itextpdf.kernel.pdf.PdfObject;
import com.itextpdf.kernel.pdf.PdfPage;
import com.itextpdf.kernel.pdf.PdfReader;
import com.itextpdf.kernel.pdf.PdfStream;
import com.itextpdf.kernel.pdf.PdfWriter;

import java.io.File;
import java.nio.charset.StandardCharsets;

public class ReplaceStream {
    public static final String DEST = "./target/sandbox/stamper/replace_stream.pdf";
    public static final String SRC = "./src/main/resources/pdfs/hello.pdf";

    public static void main(String[] args) throws Exception {
        File file = new File(DEST);
        file.getParentFile().mkdirs();

        new ReplaceStream().manipulatePdf(DEST);
    }

    protected void manipulatePdf(String dest) throws Exception {
        PdfDocument pdfDoc = new PdfDocument(new PdfReader(SRC), new PdfWriter(dest));
        PdfPage page = pdfDoc.getFirstPage();
        PdfDictionary dict = page.getPdfObject();

        PdfObject object = dict.get(PdfName.Contents);
        if (object instanceof PdfStream) {
            PdfStream stream = (PdfStream) object;
            byte[] data = stream.getBytes();
            String replacedData = new String(data).replace("Hello World", "HELLO WORLD");
            stream.setData(replacedData.getBytes(StandardCharsets.UTF_8));
        }

        pdfDoc.close();
    }
}

C#

using System;
using System.IO;
using System.Text;
using iText.Commons.Utils;
using iText.Kernel.Pdf;

namespace iText.Samples.Sandbox.Stamper 
{
    public class ReplaceStream 
    {
        public static readonly String DEST = "results/sandbox/stamper/replace_stream.pdf";
        public static readonly String SRC = "../../../resources/pdfs/hello.pdf";

        public static void Main(String[] args) 
        {
            FileInfo file = new FileInfo(DEST);
            file.Directory.Create();
            
            new ReplaceStream().ManipulatePdf(DEST);
        }

        protected void ManipulatePdf(String dest) 
        {
            PdfDocument pdfDoc = new PdfDocument(new PdfReader(SRC), new PdfWriter(dest));
            PdfPage page = pdfDoc.GetFirstPage();
            PdfDictionary dict = page.GetPdfObject();
            
            PdfObject pdfObject = dict.Get(PdfName.Contents);
            if (pdfObject is PdfStream) 
            {
                PdfStream stream = (PdfStream) pdfObject;
                byte[] data = stream.GetBytes();
                String replacedData = JavaUtil.GetStringForBytes(data).Replace("Hello World", "HELLO WORLD");
                stream.SetData((Encoding.UTF8.GetBytes(replacedData)));
            }
            
            pdfDoc.Close();
        }
    }
}