从Oracle数据库中读出图片的方法（代码教程）

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"