有时使用 VB.NET 将 BLOB 保存到 MySQL 数据库会失败。我正在保存 PDF。
当我在我的电脑上打开 PDF 时，效果很好。然后我将它保存为 db，并且通常它可以找到。我再次从数据库中检索 pdf，将其保存到文件中，然后我可以打开它。
但是有时 Acrobat Reader 不想打开新保存的 PDF，说文件已损坏。
我不确定我的代码到底哪里有缺陷。如果有人可以提供帮助，那就太好了。谢谢你。
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 " & _
"expense_invoicename=@expense_invoicename," & _
"expense_invoicefilesize=@expense_invoicefilesize," & _
"expense_invoiceblob=@expense_invoiceblob," & _
"expense_invoicetype=@expense_invoicetype, " & _
"expense_invoiceexistsinguid=@expense_invoiceexistsinguid " & _
"WHERE " & _
"expense_guid=@expense_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