从Oracle数据库中读出图片
方法1：从数据库中读取数据并以文件形式保留在服务器上
- Dim conn As New OracleClient.OracleConnection
- Dim cmd As New OracleClient.OracleCommand
- Dim myReader As OracleClient.OracleDataReader
- Dim sql As String
- Dim fl As File
-
- sql = "select * from news where newsid=3211" '从数据库中取出图片数据 blob
- conn.ConnectionString = "Password=macro;User ID=gf;Data Source=site"
- cmd.CommandText = sql
- cmd.Connection = conn
-
- conn.Open()
- myReader = cmd.ExecuteReader(CommandBehavior.SequentialAccess)
- myReader.Read()
-
- Label1.Text = myReader("title")
-
- Dim fs As FileStream ' Writes the BLOB to a file (*.bmp).
- Dim bw As BinaryWriter ' Streams the binary data to the FileStream object.
- Dim bufferSize As Integer = 1000 ' The size of the BLOB buffer.
- Dim outbyte(bufferSize - 1) As Byte ' The BLOB byte() buffer to be filled by GetBytes.
- Dim retval As Long ' The bytes returned from GetBytes.
- Dim startIndex As Long = 0 ' The starting position in the BLOB output.
- Dim fpath As String
-
- '将图片数据存成本地文件
- fpath = Server.MapPath(Request.ApplicationPath) & "\Image\photo.bmp"
- fs = New FileStream(fpath, FileMode.OpenOrCreate, FileAccess.Write)
- bw = New BinaryWriter(fs)
-
- ' Reset the starting byte for a new BLOB.
- startIndex = 0
-
- ' Read bytes into outbyte() and retain the number of bytes returned.
- retval = myReader.GetBytes(2, startIndex, outbyte, 0, bufferSize) 'GetBytes
- 返回字段中的可用字节数,第一个参数为从0开始的列序号
-
- ' Continue reading and writing while there are bytes beyond the size of the buffer.
- Do While retval = bufferSize
- bw.Write(outbyte)
- bw.Flush() '清理当前编写器的所有缓冲区，使所有缓冲数据写入基础设备。
-
- ' Reposition the start index to the end of the last buffer and fill the buffer.
- startIndex = startIndex + bufferSize
- retval = myReader.GetBytes(2, startIndex, outbyte, 0, bufferSize)
- Loop
-
- ' Write the remaining buffer.
- bw.Write(outbyte)
- bw.Flush()
-
- ' Close the output file.
- bw.Close()
- fs.Close()
-
- ' Close the reader and the connection.
- myReader.Close()
- conn.Close()
-
- Dim logo As Image '文件格式转换
- logo = Image.FromFile(fpath)
- fpath = Server.MapPath(Request.ApplicationPath) & "\Image\zkjhy.jpeg"
- logo.Save(fpath, System.Drawing.Imaging.ImageFormat.Jpeg)
-
- 'Me.Image1.Width = New Unit(300) '调整显示大小
- 'Me.Image1.Height = New Unit(350)
- Me.Image1.ImageUrl = "image/zkjhy.jpeg"
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