您如何在C# .NET中合併PDF文件？

IronPdf.License.LicenseKey = "YOUR-LICENSE-KEY-HERE";

IronPdf.License.LicenseKey = "YOUR-LICENSE-KEY-HERE"

<div class="pdf-upload-container">
    <asp:FileUpload ID="FileUpload1" runat="server" accept=".pdf" />
    <asp:Button ID="btnUpload" Text="Upload PDF"
                OnClick="btnUpload_Click" runat="server" CssClass="btn-primary" />
    <asp:Label ID="lblMessage" runat="server" CssClass="status-message" />
    <div class="file-info">
        <asp:Label ID="lblFileInfo" runat="server" />
    </div>
</div>

private void LoadPdfList()
{
    string constr = ConfigurationManager.ConnectionStrings["DefaultConnection"].ConnectionString;
    using (SqlConnection conn = new SqlConnection(constr))
    {
        string query = @"SELECT Id, FileName, FileSize, UploadDate, CreatedBy
                        FROM PdfDocuments
                        ORDER BY UploadDate DESC";
        using (SqlCommand cmd = new SqlCommand(query, conn))
        {
            conn.Open();
            SqlDataAdapter adapter = new SqlDataAdapter(cmd);
            DataTable dt = new DataTable();
            adapter.Fill(dt);

            foreach (DataRow row in dt.Rows)
            {
                int fileSize = Convert.ToInt32(row["FileSize"]);
                row["FileSize"] = FormatFileSize(fileSize);
            }

            GridView1.DataSource = dt;
            GridView1.DataBind();
        }
    }
}

private string FormatFileSize(int bytes)
{
    if (bytes < 1024) return bytes + " B";
    if (bytes < 1048576) return (bytes / 1024) + " KB";
    return (bytes / 1048576) + " MB";
}

private PdfData GetPdfFromDatabase(int id)
{
    byte[] pdfBytes = null;
    string filename = "";
    string constr = ConfigurationManager.ConnectionStrings["DefaultConnection"].ConnectionString;
    using (SqlConnection conn = new SqlConnection(constr))
    {
        string query = "SELECT FileData, FileName FROM PdfDocuments WHERE Id = @Id";
        using (SqlCommand cmd = new SqlCommand(query, conn))
        {
            cmd.Parameters.AddWithValue("@Id", id);
            conn.Open();
            using (SqlDataReader reader = cmd.ExecuteReader())
            {
                if (reader.Read())
                {
                    pdfBytes = (byte[])reader["FileData"];
                    filename = reader["FileName"].ToString();
                }
            }
        }
    }
    if (pdfBytes != null)
    {
        return new PdfData { Bytes = pdfBytes, FileName = filename };
    }
    return null;
}

protected void GridView1_RowCommand(object sender, GridViewCommandEventArgs e)
{
    if (e.CommandName == "ViewPdf")
    {
        int documentId = Convert.ToInt32(e.CommandArgument);
        ViewPdfDocument(documentId);
    }
    else if (e.CommandName == "DownloadPdf")
    {
        int documentId = Convert.ToInt32(e.CommandArgument);
        DownloadPdfDocument(documentId);
    }
}

private void ViewPdfDocument(int id)
{
    var pdfData = GetPdfFromDatabase(id);
    if (pdfData != null)
    {
        IronPdf.PdfDocument pdf;
        using (var stream = new System.IO.MemoryStream(pdfData.Bytes))
        {
            pdf = new IronPdf.PdfDocument(stream);
        }

        // Apply security settings
        pdf.SecuritySettings.AllowUserPrinting = true;
        pdf.SecuritySettings.AllowUserCopyPasteContent = false;

        Response.Clear();
        Response.ContentType = "application/pdf";
        Response.AddHeader("content-disposition", $"inline; filename={pdfData.FileName}");
        Response.AddHeader("content-length", pdf.BinaryData.Length.ToString());
        Response.BinaryWrite(pdf.BinaryData);
        Response.End();
    }
}

Imports System.Configuration
Imports System.Data
Imports System.Data.SqlClient
Imports System.IO
Imports IronPdf

Private Sub LoadPdfList()
    Dim constr As String = ConfigurationManager.ConnectionStrings("DefaultConnection").ConnectionString
    Using conn As New SqlConnection(constr)
        Dim query As String = "SELECT Id, FileName, FileSize, UploadDate, CreatedBy FROM PdfDocuments ORDER BY UploadDate DESC"
        Using cmd As New SqlCommand(query, conn)
            conn.Open()
            Dim adapter As New SqlDataAdapter(cmd)
            Dim dt As New DataTable()
            adapter.Fill(dt)

            For Each row As DataRow In dt.Rows
                Dim fileSize As Integer = Convert.ToInt32(row("FileSize"))
                row("FileSize") = FormatFileSize(fileSize)
            Next

            GridView1.DataSource = dt
            GridView1.DataBind()
        End Using
    End Using
End Sub

Private Function FormatFileSize(bytes As Integer) As String
    If bytes < 1024 Then Return bytes & " B"
    If bytes < 1048576 Then Return (bytes \ 1024) & " KB"
    Return (bytes \ 1048576) & " MB"
End Function

Private Function GetPdfFromDatabase(id As Integer) As PdfData
    Dim pdfBytes As Byte() = Nothing
    Dim filename As String = ""
    Dim constr As String = ConfigurationManager.ConnectionStrings("DefaultConnection").ConnectionString
    Using conn As New SqlConnection(constr)
        Dim query As String = "SELECT FileData, FileName FROM PdfDocuments WHERE Id = @Id"
        Using cmd As New SqlCommand(query, conn)
            cmd.Parameters.AddWithValue("@Id", id)
            conn.Open()
            Using reader As SqlDataReader = cmd.ExecuteReader()
                If reader.Read() Then
                    pdfBytes = CType(reader("FileData"), Byte())
                    filename = reader("FileName").ToString()
                End If
            End Using
        End Using
    End Using
    If pdfBytes IsNot Nothing Then
        Return New PdfData With {.Bytes = pdfBytes, .FileName = filename}
    End If
    Return Nothing
End Function

Protected Sub GridView1_RowCommand(sender As Object, e As GridViewCommandEventArgs)
    If e.CommandName = "ViewPdf" Then
        Dim documentId As Integer = Convert.ToInt32(e.CommandArgument)
        ViewPdfDocument(documentId)
    ElseIf e.CommandName = "DownloadPdf" Then
        Dim documentId As Integer = Convert.ToInt32(e.CommandArgument)
        DownloadPdfDocument(documentId)
    End If
End Sub

Private Sub ViewPdfDocument(id As Integer)
    Dim pdfData = GetPdfFromDatabase(id)
    If pdfData IsNot Nothing Then
        Dim pdf As PdfDocument
        Using stream As New MemoryStream(pdfData.Bytes)
            pdf = New PdfDocument(stream)
        End Using

        ' Apply security settings
        pdf.SecuritySettings.AllowUserPrinting = True
        pdf.SecuritySettings.AllowUserCopyPasteContent = False

        Response.Clear()
        Response.ContentType = "application/pdf"
        Response.AddHeader("content-disposition", $"inline; filename={pdfData.FileName}")
        Response.AddHeader("content-length", pdf.BinaryData.Length.ToString())
        Response.BinaryWrite(pdf.BinaryData)
        Response.End()
    End If
End Sub