和儲存圖片相比,讀取圖片就要簡單多了。輸出一副圖片我們要做的就是使用Response對象的BinaryWrite方法。
同時設定圖片的格式。在這篇文章中,我們將討論如何從SqlServer中檢索圖片。並將學習以下幾個方面的知識。
·如何設定圖片的格式?
·如何使用BinaryWrite方法。
我們已經在Person表中儲存了資料,那麼我們就寫些代碼來從表中讀取資料。
下面的代碼檢索了所有的值從Person表中。
從sqlserver中讀取圖片的代碼。
Public Sub Page_Load(sender As Object, e As EventArgs)
Dim myConnection As New SqlConnection(ConfigurationSettings.AppSettings("ConnectionString"))
Dim myCommand As New SqlCommand("Select * from Person", myConnection)
Try
myConnection.Open()
Dim myDataReader as SqlDataReader
myDataReader = myCommand.ExecuteReader(CommandBehavior.CloseConnection)
Do While (myDataReader.Read())
Response.ContentType = myDataReader.Item("PersonImageType")
Response.BinaryWrite(myDataReader.Item("PersonImage"))
Loop
myConnection.Close()
Response.Write("Person info successfully retrieved!")
Catch SQLexc As SqlException
Response.Write("Read Failed : " & SQLexc.ToString())
End Try
End Sub
看看他是怎麼工作的?
上面的例子很簡單。我們所作的就是執行一個sql語句,再迴圈讀取所有的記錄(looping through all the records).
在顯示圖片之前,我們先設定了圖片的contentType,然後我們使用BinaryWrite方法把圖片輸出到瀏覽器。
原始碼:
/// retriving.aspx
<%@ Page Language="vb" %>
<%@ Import Namespace="System.Data" %>
<%@ Import Namespace="System.Data.SqlClient" %>
<HTML>
<HEAD>
<title>Retrieving Image from the Sql Server</title>
<script runat=server>
Public Sub Page_Load(sender As Object, e As EventArgs)
' Create Instance of Connection and Command Object
Dim myConnection As New SqlConnection(ConfigurationSettings.AppSettings("ConnectionString"))
Dim myCommand As New SqlCommand("Select * from Person", myConnection)
Try
myConnection.Open()
Dim myDataReader as SqlDataReader
myDataReader = myCommand.ExecuteReader(CommandBehavior.CloseConnection)
Do While (myDataReader.Read())
Response.ContentType = myDataReader.Item("PersonImageType")
Response.BinaryWrite(myDataReader.Item("PersonImage"))
Loop
myConnection.Close()
Response.Write("Person info successfully retrieved!")
Catch SQLexc As SqlException
Response.Write("Read Failed : " & SQLexc.ToString())
End Try
End Sub
</script>
</HEAD>
<body style="font: 10pt verdana">
</body>
</HTML>