在Asp.Net中从sqlserver检索(retrieve)图片
浏览：27日期：2023-04-18
出处：www.ASPAlliance.com介绍：这篇文章是我写的"如何把图片存入sqlServer中"的后续。我建议你在读这篇文章之前先看看那篇。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 SqlDataReader myDataReader = 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 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 SqlExceptionResponse.Write("Read Failed : " & SQLexc.ToString())End TryEnd Sub;;;;</script> </HEAD><body style="font: 10pt verdana"></body></HTML>
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