如何在 C# 中合并 PDF 字节数组

Install-Package IronPdf

dotnet add package IronPdf

using IronPdf;
using System.IO;
using System.Collections.Generic;

Imports IronPdf
Imports System.IO
Imports System.Collections.Generic

// Simulate two PDF byte arrays (in practice, these come from a database or API)
byte[] pdfBytes1 = File.ReadAllBytes("document1.pdf");
byte[] pdfBytes2 = File.ReadAllBytes("document2.pdf");

// Create PdfDocument objects from byte arrays
var pdf1 = new PdfDocument(pdfBytes1);
var pdf2 = new PdfDocument(pdfBytes2);

// Merge the two PDF documents
PdfDocument combinedPdf = PdfDocument.Merge(pdf1, pdf2);

// Convert the combined PDF back to a byte array
byte[] mergedPdfBytes = combinedPdf.BinaryData;

// Optionally save the merged PDF to disk
File.WriteAllBytes("merged.pdf", mergedPdfBytes);

Imports System.IO

' Simulate two PDF byte arrays (in practice, these come from a database or API)
Dim pdfBytes1 As Byte() = File.ReadAllBytes("document1.pdf")
Dim pdfBytes2 As Byte() = File.ReadAllBytes("document2.pdf")

' Create PdfDocument objects from byte arrays
Dim pdf1 As New PdfDocument(pdfBytes1)
Dim pdf2 As New PdfDocument(pdfBytes2)

' Merge the two PDF documents
Dim combinedPdf As PdfDocument = PdfDocument.Merge(pdf1, pdf2)

' Convert the combined PDF back to a byte array
Dim mergedPdfBytes As Byte() = combinedPdf.BinaryData

' Optionally save the merged PDF to disk
File.WriteAllBytes("merged.pdf", mergedPdfBytes)

// Load four PDFs as byte arrays
List<byte[]> pdfByteArrays = new List<byte[]>
{
    File.ReadAllBytes("example1.pdf"),
    File.ReadAllBytes("example2.pdf"),
    File.ReadAllBytes("example3.pdf"),
    File.ReadAllBytes("example4.pdf")
};

// Convert each byte array to a PdfDocument
List<PdfDocument> pdfsToMerge = new List<PdfDocument>();
for (int i = 0; i < pdfByteArrays.Count; i++)
{
    pdfsToMerge.Add(new PdfDocument(pdfByteArrays[i]));
}

// Merge all documents in one call
PdfDocument combinedPdf = PdfDocument.Merge(pdfsToMerge);
byte[] finalPdfBytes = combinedPdf.BinaryData;

// Apply compression if the result is large
if (finalPdfBytes.Length > 1024 * 1024 * 10) // 10 MB
{
    combinedPdf.CompressImages(90);
    finalPdfBytes = combinedPdf.BinaryData;
}

Imports System.IO

' Load four PDFs as byte arrays
Dim pdfByteArrays As New List(Of Byte()) From {
    File.ReadAllBytes("example1.pdf"),
    File.ReadAllBytes("example2.pdf"),
    File.ReadAllBytes("example3.pdf"),
    File.ReadAllBytes("example4.pdf")
}

' Convert each byte array to a PdfDocument
Dim pdfsToMerge As New List(Of PdfDocument)()
For i As Integer = 0 To pdfByteArrays.Count - 1
    pdfsToMerge.Add(New PdfDocument(pdfByteArrays(i)))
Next

' Merge all documents in one call
Dim combinedPdf As PdfDocument = PdfDocument.Merge(pdfsToMerge)
Dim finalPdfBytes As Byte() = combinedPdf.BinaryData

' Apply compression if the result is large
If finalPdfBytes.Length > 1024 * 1024 * 10 Then ' 10 MB
    combinedPdf.CompressImages(90)
    finalPdfBytes = combinedPdf.BinaryData
End If

public string MergePdfDocumentsFromDatabase(List<int> documentIds)
{
    List<PdfDocument> documents = new List<PdfDocument>();

    try
    {
        foreach (int id in documentIds)
        {
            // Fetch PDF byte array from database
            byte[] pdfData = GetPdfFromDatabase(id); // Replace with your data access logic

            if (pdfData == null || pdfData.Length == 0)
            {
                Console.WriteLine($"Warning: Document {id} is empty or not found");
                continue;
            }

            documents.Add(new PdfDocument(pdfData));
        }

        if (documents.Count == 0)
        {
            return "Error: No valid documents found to merge";
        }

        // Merge all documents
        PdfDocument mergedDocument = PdfDocument.Merge(documents);

        // Add page numbers to the footer
        mergedDocument.AddHtmlFooters(new HtmlHeaderFooter()
        {
            HtmlFragment = "<center>Page {page} of {total-pages}</center>",
            DrawDividerLine = true
        });

        // Save back to the database
        byte[] resultBytes = mergedDocument.BinaryData;
        SaveMergedPdfToDatabase(resultBytes);

        return "Document successfully combined and saved.";
    }
    catch (Exception ex)
    {
        Console.WriteLine($"Error merging PDFs: {ex.Message}");
        return $"Merge failed: {ex.Message}";
    }
}

Imports System

Public Function MergePdfDocumentsFromDatabase(documentIds As List(Of Integer)) As String
    Dim documents As New List(Of PdfDocument)()

    Try
        For Each id As Integer In documentIds
            ' Fetch PDF byte array from database
            Dim pdfData As Byte() = GetPdfFromDatabase(id) ' Replace with your data access logic

            If pdfData Is Nothing OrElse pdfData.Length = 0 Then
                Console.WriteLine($"Warning: Document {id} is empty or not found")
                Continue For
            End If

            documents.Add(New PdfDocument(pdfData))
        Next

        If documents.Count = 0 Then
            Return "Error: No valid documents found to merge"
        End If

        ' Merge all documents
        Dim mergedDocument As PdfDocument = PdfDocument.Merge(documents)

        ' Add page numbers to the footer
        mergedDocument.AddHtmlFooters(New HtmlHeaderFooter() With {
            .HtmlFragment = "<center>Page {page} of {total-pages}</center>",
            .DrawDividerLine = True
        })

        ' Save back to the database
        Dim resultBytes As Byte() = mergedDocument.BinaryData
        SaveMergedPdfToDatabase(resultBytes)

        Return "Document successfully combined and saved."
    Catch ex As Exception
        Console.WriteLine($"Error merging PDFs: {ex.Message}")
        Return $"Merge failed: {ex.Message}"
    End Try
End Function