我在iTextSharp中很新，我有以下情况：我正在创建一个包含页眉和页脚的PDF（对于页眉和页脚创建，我使用一个扩展PdfPageEventHelper的类，并且我覆盖了OnStartPage（）和OnEndPage（）方法，它可以正常工作）。

现在我的问题是我必须在页脚中插入Y的X页。其中X**是**当前页码，Y是总页码。Y的值不是固定的（因为我的PDF的长度事先不知道，因为它取决于内容的长度，并且可能PDFPDF不同）。我如何处理这种情况？（在每个页脚中插入正确的Y值？）

在网上搜索我找到了这个教程（这是JavaiText，但也许它不是那么不同于iTextSharp版本）：http://itextpdf.com/examples/iia.php?id=104

在此示例中，它创建了一个PDF，其标题包含类似于Y的Page X的内容。

我试图理解这个例子（并将其翻译为iTextSharp），但我对它是如何工作的有些怀疑（以及它是否是我问题的真正解决方案）。

据我所知，它执行以下操作：

在扩展PdfPageEventHelper的类中，它被声明为PdfTemplate对象

PdfTemplate total;

我认为，也许它处理的总页数，是到我的PDF文档，但阅读官方留档我没有太多的信息，究竟做这个类：http://api.itextpdf.com/itext/com/itextpdf/text/pdf/PdfTemplate.html

我正在尝试做一些类似的事情到我的类中，扩展PdfPageEventHelper，但我做不到。

这是我不工作的代码：

public class PdfHeaderFooter : PdfPageEventHelper
{

    // The template with the total number of pages:
    PdfTemplate total;

    private static int numPagina = 1;

    public Image CellImage;
    private string folderImages;
    private string _sourceId;


    public PdfHeaderFooter(string _folderImages, string sourceId)
    {
        folderImages = _folderImages;
        _sourceId = sourceId;

    }


    /* Creates the PdfTemplate that will hold the total number of pages.
     * Write on top of document
     * */
    public override void OnOpenDocument(PdfWriter writer, Document document)
    {

        base.OnOpenDocument(writer, document);

        // (Nobili) Page Number:
        total = writer.DirectContent.CreateTemplate(30, 16);

        //PdfPTable tabFot = new PdfPTable(new float[] { 1F });
        PdfPTable tabFot = new PdfPTable(2);
        tabFot.WidthPercentage = 98;
        tabFot.SpacingAfter = 10F;
        PdfPCell cell;
        //tabFot.TotalWidth = 300F;
        cell = new PdfPCell(new Phrase("Header"));
        tabFot.AddCell(cell);
        tabFot.WriteSelectedRows(0, -1, 150, document.Top, writer.DirectContent);
    }


    // write on end of each page
    public override void OnEndPage(PdfWriter writer, Document document)
    {
        base.OnEndPage(writer, document);

        int pageN = writer.PageNumber;
        String text = "Page " + pageN + " of ";

        //PdfPTable tabFoot = new PdfPTable(new float[] { 1F });
        PdfPTable tabFoot = new PdfPTable(3);
        tabFoot.TotalWidth = document.Right - document.Left;

        tabFoot.DefaultCell.Border = PdfPCell.NO_BORDER;
        tabFoot.DefaultCell.CellEvent = new RoundedBorder();

        PdfPTable innerTable = new PdfPTable(2);
        innerTable.SetWidths(new int[] { 247, 246 });
        innerTable.TotalWidth = document.Right - document.Left;
        innerTable.DefaultCell.Border = PdfPCell.NO_BORDER;
        PdfPCell innerCellLeft = new PdfPCell(new Phrase("Early Warning - Bollettino")) { Border = PdfPCell.NO_BORDER, Padding = 5, MinimumHeight = 20, HorizontalAlignment = Element.ALIGN_LEFT };
        //PdfPCell innerCellRight = new PdfPCell(new Phrase("Pag. " + numPagina + "/5")) { Border = PdfPCell.NO_BORDER, Padding = 5, MinimumHeight = 20, HorizontalAlignment = Element.ALIGN_RIGHT };
        PdfPCell innerCellCenter = new PdfPCell(new Phrase(text)) { Border = PdfPCell.NO_BORDER, Padding = 5, MinimumHeight = 20, HorizontalAlignment = Element.ALIGN_RIGHT };
        PdfPCell innerCellRight = new PdfPCell(Image.GetInstance(total)) { Border = PdfPCell.NO_BORDER, Padding = 5, MinimumHeight = 20, HorizontalAlignment = Element.ALIGN_RIGHT };

        innerTable.AddCell(innerCellLeft);
        innerTable.AddCell(innerCellRight);

        tabFoot.AddCell(innerTable);

        tabFoot.WriteSelectedRows(0, -1, document.Left, document.Bottom, writer.DirectContent);

        numPagina++;
    }


    // write on start of each page
    public override void OnStartPage(PdfWriter writer, Document document)
    {
        base.OnStartPage(writer, document);
        PdfPTable tabHead = new PdfPTable(3);
        tabHead.SetWidths(new int[] { 165, 205, 125 });

        //tabHead.TotalWidth = 460F;
        tabHead.TotalWidth = document.Right - document.Left;        // TotalWidth = 495
        tabHead.WidthPercentage = 98;


        PdfPCell cell1 = new PdfPCell(iTextSharp.text.Image.GetInstance(folderImages + "logoEarlyWarning.png"), true) { Border = PdfPCell.BOTTOM_BORDER };
        tabHead.AddCell(cell1);
        //tabHead.AddCell(new PdfPCell(new Phrase("CELL 1:")) { Border = PdfPCell.BOTTOM_BORDER, Padding = 5, MinimumHeight = 50, PaddingTop = 15, });

        tabHead.AddCell(new PdfPCell(new Phrase("CELL 2:")) { Border = PdfPCell.BOTTOM_BORDER, Padding = 5, MinimumHeight = 50, PaddingTop = 15 });

        if(_sourceId == "NVD")
        {
            iTextSharp.text.Image logo = iTextSharp.text.Image.GetInstance(folderImages + "nvdLogo.png");
            logo.ScalePercent(48f);
            //PdfPCell cell3 = new PdfPCell(iTextSharp.text.Image.GetInstance(folderImages + "nvdLogo.png"), true) { Border = PdfPCell.BOTTOM_BORDER, PaddingBottom = 25 };
            PdfPCell cell3 = new PdfPCell(logo) { Border = PdfPCell.BOTTOM_BORDER, PaddingLeft = 50 };
            tabHead.AddCell(cell3);
        }
        else if(_sourceId == "DeepSight")
        {
            PdfPCell cell3 = new PdfPCell(iTextSharp.text.Image.GetInstance(folderImages + "DSLogo.jpg"), true) { Border = PdfPCell.BOTTOM_BORDER };
            tabHead.AddCell(cell3);
        }
        //tabHead.AddCell(new PdfPCell(new Phrase("CELL 3:")) { Border = PdfPCell.BOTTOM_BORDER, Padding = 5, MinimumHeight = 50, PaddingTop = 15 });


        tabHead.WriteSelectedRows(0, -1, document.Left, document.Top, writer.DirectContent);
    }



    //write on close of document
    public override void OnCloseDocument(PdfWriter writer, Document document)
    {
        base.OnCloseDocument(writer, document);
    }



}

}

我想在页脚中放入类似于教程中所示的Y的第X页的内容

我尝试做以下事情：

1）我声明了PdfTemplate总计；对象作为我的类的字段，并将其初始化为我的OnOpenDocument（）方法

 total = writer.DirectContent.CreateTemplate(30, 16);

2）在我的OnEndPage（）方法中，我放了：

String text = "Page " + pageN + " of ";

我创建了下表来显示Y的X页

PdfPCell innerCellLeft = new PdfPCell(new Phrase("Early Warning - Bollettino")) { Border = PdfPCell.NO_BORDER, Padding = 5, MinimumHeight = 20, HorizontalAlignment = Element.ALIGN_LEFT };
PdfPCell innerCellCenter = new PdfPCell(new Phrase(text)) { Border = PdfPCell.NO_BORDER, Padding = 5, MinimumHeight = 20, HorizontalAlignment = Element.ALIGN_RIGHT };
            PdfPCell innerCellRight = new PdfPCell(Image.GetInstance(total)) { Border = PdfPCell.NO_BORDER, Padding = 5, MinimumHeight = 20, HorizontalAlignment = Element.ALIGN_RIGHT };

但它不起作用，给我一个例外

我的代码中可能有什么问题？