將二進制轉換爲圖像的錯誤

Question

我嘗試將圖像從mssql varbinary（max）列導入到iTextSharp。 但它總是顯示了錯誤「的NullReferenceException」「phrase.Add（imageChunk）」

我的代碼是：

Dim conn As New SqlConnection(ConfigurationManager.ConnectionStrings("dbconnection").ConnectionString) 

Dim q As String = "select top 1 pic_id from pic" 
Dim cmd As SqlCommand = New SqlCommand(q, conn) 
conn.Open() 
Dim sr As SqlDataReader = cmd.ExecuteReader 

While sr.Read 
    Dim byt() As Byte = CType(sr.Item("pic_id"), Byte()) 
    Dim ms As MemoryStream = New MemoryStream(byt) 
    Dim sdi As System.Drawing.Image = System.Drawing.Image.FromStream(ms) 
    Dim img As Image = Image.GetInstance(sdi, ImageFormat.Jpeg) 

    Dim imageChunk As Chunk = New Chunk(img, 0, 0) 
    phrase.Add(imageChunk) 
End While 

該列的數據類型爲「VARBINARY（最大）」和數據是這樣的：（0x89504E470D0A1A0A0000000D494 ....................）

Answer 1

你的變量「phrase」沒有設置，它是Nothing/null。確保將正確的「短語」傳遞給你的方法，它很可能會解決你的問題。