高效合并文件块

Question

您好，我正在尝试将拆分文件重新合并在一起。我有这个代码工作，但它非常缓慢。有什么想法可以加快速度吗？每个文件块最多可以包含 5mb 个块，并且可以有 100 个或更多块可以重新组合在一起。我将块文件路径“mergeFileNameArray”的数组以及新合并文件的“文件名”传递给它。

非常感谢！

    Dim STo As System.IO.Stream = System.IO.File.Open _
                (filename, _
                 System.IO.FileMode.Create, _
                 System.IO.FileAccess.Write)
    Dim BW As New System.IO.BinaryWriter(STo)

    For Each F In mergeFileNameArray
        Dim STi As System.IO.Stream = System.IO.File.Open _
             (F, _
              System.IO.FileMode.Open, _
              System.IO.FileAccess.Read)
        Dim BR As New System.IO.BinaryReader(STi)
        Do Until (BR.BaseStream.Position = BR.BaseStream.Length)
            BW.Write(BR.ReadByte)
        Loop
        BR.Close()
    Next
    BW.Close()

Answer 1

一次复制一个字节的文件效率并不高。相反，您可以使用缓冲区和FileStreams 复制文件块；这是最基本的：

Option Infer On
Imports System.IO

Module Module1

    Sub ConcatenateFileParts(fileParts As String(), destFile As String)
        Using outStream As New FileStream(destFile, FileMode.Create, FileAccess.Write, FileShare.None)
            Dim bufferLength = 32768
            Dim buffer(bufferLength - 1) As Byte
            Dim bytesRead As Integer
            For Each inFile In fileParts
                Using inStream As New FileStream(inFile, FileMode.Open, FileAccess.Read, FileShare.Read)
                    bytesRead = inStream.Read(buffer, 0, bufferLength)
                    While bytesRead > 0
                        outStream.Write(buffer, 0, bytesRead)
                        bytesRead = inStream.Read(buffer, 0, bufferLength)
                    End While
                End Using
            Next
        End Using

    End Sub

    Sub Main()
        ' I put a couple of files in "C:\temp\subdir" for testing.
        Dim filesToMerge = Directory.GetFiles("C:\temp\subdir")
        Dim dest = "C:\temp\merged.txt"
        Try
            ConcatenateFileParts(filesToMerge, dest)
        Catch ex As Exception
            MsgBox("File merge failed because " & ex.Message)
        End Try

    End Sub

End Module

Using 构造确保文件流被正确关闭和处理。

您可以通过报告进度来使其更加复杂，例如在复制每个文件部分后增加一个计数器。