和存储图片相比,读取图片就要简单多了。输出一副图片我们要做的就是使用Response对象的BinaryWrite方法。
同时设置图片的格式。在这篇文章中,我们将讨论如何从SqlServer中检索图片。并将学习以下几个方面的知识。
·如何设置图片的格式?
·如何使用BinaryWrite方法。
我们已经在Person表中存储了数据,那么我们就写些代码来从表中读取数据。
下面的代码检索了所有的值从Person表中。
从sqlserver中读取图片的代码。
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)TrymyConnection.Open()Dim myDataReader as SqlDataReadermyDataReader = myCommand.ExecuteReader(CommandBehavior.CloseConnection)Do While (myDataReader.Read())Response.ContentType = myDataReader.Item("PersonImageType")Response.BinaryWrite(myDataReader.Item("PersonImage"))LoopmyConnection.Close()Response.Write("Person info successfully retrieved!")Catch SQLexc As SqlExceptionResponse.Write("Read Failed : " & SQLexc.ToString())End TryEnd Sub
看看他是怎么工作的?
上面的例子很简单。我们所作的就是执行一个sql语句,再循环读取所有的记录(looping through all the records).
在显示图片之前,我们先设置了图片的contentType,然后我们使用BinaryWrite方法把图片输出到浏览器。
源代码:
/// 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 ObjectDim myConnection As New SqlConnection(ConfigurationSettings.AppSettings("ConnectionString"))Dim myCommand As New SqlCommand("Select * from Person", myConnection)TrymyConnection.Open()Dim myDataReader as SqlDataReadermyDataReader = myCommand.ExecuteReader(CommandBehavior.CloseConnection)Do While (myDataReader.Read())Response.ContentType = myDataReader.Item("PersonImageType")Response.BinaryWrite(myDataReader.Item("PersonImage"))LoopmyConnection.Close()Response.Write("Person info successfully retrieved!")Catch SQLexc As SqlExceptionResponse.Write("Read Failed : " & SQLexc.ToString())End TryEnd Sub</script></HEAD><body style="font: 10pt verdana"></body></HTML>