VB.NET某些文件的MySQL blob保存失败

有时使用VB.NET将一个BLOB保存到一个MySQL数据库失败。我正在保存PDF文件。VB.NET某些文件的MySQL blob保存失败

当我在计算机上打开PDF时，效果很好。然后我将它保存为db，并且大多数情况下它都可以找到。我再次从数据库中检索pdf，将其保存到一个文件，我可以打开它。

但是有时Acrobat Reader不想打开新保存的PDF文件，说该文件已损坏。

我不确定在我的代码中有什么缺陷。如果有人能帮忙，这将是非常好的。谢谢。

Private Function pUpdateInvoice(ByVal uGUID As String, ByVal uPath As String) As Boolean 

    Dim rawData() As Byte 
    Dim fs As FileStream 

    Try 
     fs = New FileStream(uPath, FileMode.Open, FileAccess.Read) 

     Dim iFileSize As UInt32 
     iFileSize = fs.Length 

     rawData = New Byte(iFileSize) {} 
     fs.Read(rawData, 0, iFileSize) 
     fs.Close() 

     If Not g_CnWebDB.Ping Then 
      InitMySQL() 
     End If 

     Dim sFileName$ 
     sFileName = CleanFile(uPath, False) 

     Dim sSQL 
     sSQL = "UPDATE expenses SET " & _ 
      "[email protected]_invoicename," & _ 
      "[email protected]_invoicefilesize," & _ 
      "[email protected]_invoiceblob," & _ 
      "[email protected]_invoicetype, " & _ 
      "[email protected]_invoiceexistsinguid " & _ 
      "WHERE " & _ 
      "[email protected]_guid" 

     Dim cmd As New MySqlCommand 
     cmd.Connection = g_CnWebDB 
     cmd.CommandText = sSQL 
     cmd.Parameters.AddWithValue("expense_invoicename", sFileName) 
     cmd.Parameters.AddWithValue("expense_invoicefilesize", iFileSize) 
     cmd.Parameters.AddWithValue("expense_invoiceblob", rawData) 
     cmd.Parameters.AddWithValue("expense_invoicetype", eInvoiceType.eIT_Digital) 
     cmd.Parameters.AddWithValue("expense_invoiceexistsinguid", "") 
     cmd.Parameters.AddWithValue("expense_guid", uGUID) 

     cmd.ExecuteNonQuery() 

     Return True 

    Catch ex As Exception 
     MessageBox.Show("There was an error: " & ex.Message, "Error", _ 
      MessageBoxButtons.OK, MessageBoxIcon.Error) 
    End Try 

    Return False 

End Function 

Private Sub pShowPDF(ByVal uGUID As String) 

    If Not g_CnWebDB.Ping Then 
     InitMySQL() 
    End If 

    Dim cmdSel As New MySqlCommand("SELECT * FROM expenses WHERE expense_guid=" & Apo(uGUID), g_CnWebDB) 
    Dim r As MySqlDataReader 
    r = cmdSel.ExecuteReader 

    If Not r.HasRows Then 
     Stop 
    End If 

    r.Read() 

    Dim FileSize As UInt32 
    FileSize = r.GetUInt32(r.GetOrdinal("expense_invoicefilesize")) 
    Dim rawData() As Byte 
    rawData = New Byte(FileSize) {} 

    r.GetBytes(r.GetOrdinal("expense_invoiceblob"), 0, rawData, 0, FileSize) 
    r.Close() 

    Dim sPath$ 
    sPath = "m:\temp.pdf" 
    modIO.DeleteFile(sPath) 

    Dim fs As FileStream 
    fs = New FileStream(sPath, FileMode.OpenOrCreate, FileAccess.Write) 
    fs.Write(rawData, 0, FileSize) 
    fs.Close() 

    Dim id As Integer 
    id = System.Diagnostics.Process.Start(sPath).Id 

End Sub

来源

2013-05-10 tmighty

我会尝试在写入流关闭之前添加'fs.Flush（）;'。并且可能在创建和关闭时使用声明以确保正确处理流。不能在这里测试，所以，如果它工作让我知道 – Steve 2013-05-10 11:23:16

@Steve谢谢你，但没有帮助。 – tmighty 2013-05-10 11:29:08

我发现（使用WinHex）我的磁盘上的pdf（我保存到数据库）中的某个点上有0个数据，而来自db的pdf有更多的数据。我想r.GetBytes（r.GetOrdinal（“expense_invoiceblob”），0，rawData，0，FileSize）填充一些垃圾。也许FileSize（声明为UInt32）是错误的？ – tmighty 2013-05-10 11:42:33

我在db中选择了“blob”作为列类型。相反，我应该选择“longblob”。

来源

2013-05-10 11:58:14 tmighty

VB.NET某些文件的MySQL blob保存失败

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