[.Net] - 使用 iTextSharp 生成基于模板的 PDF，生成新文件并保留表单域

using iTextSharp.text.pdf;

/* Code Snippet */
using (var dia = new SaveFileDialog())
{
    dia.Filter = @"PDF files|*.pdf";
    dia.FileName = string.Format("PDF_{0}", DateTime.Today.ToString("yyyy-MM-dd"));
    if (dia.ShowDialog() == DialogResult.OK)
    {
        using (FileStream fsWrite = new FileStream(dia.FileName, FileMode.OpenOrCreate, FileAccess.Write))
        {
            using (var reader = new PdfReader(@"\Templates\PDFTemplate\Template01.pdf"))
            {
                using (var stamper = new PdfStamper(reader, fsWrite))
                {
                    stamper.Writer.CloseStream = false;

                    // 保留表单域，允许继续编辑
                    stamper.FormFlattening = false;

                    // 更新表单域字段
                    var form = stamper.AcroFields;
                    form.SetField("form1[0].#subform[0].flt_txtUserName[0]", "username");
                    stamper.Close();
                }
            }
        }
        MessageBox.Show("Report has been exported", Resources.Common_Successed, MessageBoxButtons.OK, MessageBoxIcon.Information);
    }
}