在Asp.Net中從sqlserver檢索(retrieve)圖片
2024-07-10 12:58:04
供稿：網(wǎng)友
介紹：
這篇文章是我寫的"如何把圖片存入sqlserver中"的后續(xù)。我建議你在讀這篇文章之前先看看那篇。
和存儲(chǔ)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(duì)象的binarywrite方法。
同時(shí)設(shè)置圖片的格式。在這篇文章中，我們將討論如何從sqlserver中檢索圖片。
并將學(xué)習(xí)以下幾個(gè)方面的知識(shí).
·如何設(shè)置圖片的格式？
·如何使用binarywrite方法。
我們已經(jīng)在person表中存儲(chǔ)了數(shù)據(jù)，那么我們就寫些代碼來從表中讀取數(shù)據(jù)。
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
看看他是怎么工作的？
上面的例子很簡單。我們所作的就是執(zhí)行一個(gè)sql語句，再循環(huán)讀取所有的記錄（looping through all the records）.
在顯示圖片之前，我們先設(shè)置了圖片的contenttype，然后我們使用binarywrite方法把圖片輸出到瀏覽器。
源代碼：
/// 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>
