用asp.net实现将上传的图片变小存入数据库！（暑假里就开始想做

2022-07-15 80酷酷网 80kuku.com

　　asp.net|上传|数据|数据库我校的学生网：www.ehang.com.cn中有校友录和图库等的项目有上传图片的功能，我将图片数据存入数据库中，需要将图片变小后和原图片一块存入数据库中，这样先可显示很多小图，点击后再显示大图！在asp.net中是这么做的：
changimage.aspx中代码：
<% Page Language="vb" AutoEventWireup="false" Codebehind="changimage.aspx.vb" Inherits="uploadimage.changimage"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML>
    <HEAD>
        <title></title>
        <meta name="GENERATOR" content="Microsoft Visual Studio.NET 7.0">
        <meta name="CODE_LANGUAGE" content="Visual Basic 7.0">
        <meta name="vs_defaultClientScript" content="JavaScript">
        <meta name="vs_targetSchema" content="http://schemas.microsoft.com/intellisense/ie5">
    </HEAD>
    <body MS_POSITIONING="GridLayout">
        <form id="Form1" method="post" enctype="multipart/form-data" runat="server">
            <FONT face="宋体"><INPUT id="File1" 101; LEFT: 291px; WIDTH: 180px; POSITION: absolute; TOP: 119px; HEIGHT: 45px" type="file" size="10" name="File1" runat="server">                        <asp:Button id="cmdupload" 103; LEFT: 402px; POSITION: absolute; TOP: 194px" runat="server" Text="上传图片" Width="81px" Height="42px"></asp:Button>
            </FONT>
        </form>
    </body>
</HTML>
changimage.aspx.vb中代码如下:
Public Class changimage
    Inherits System.Web.UI.Page
    Protected WithEvents cmddemo As System.Web.UI.WebControls.Button
    Protected WithEvents cmdupload As System.Web.UI.WebControls.Button
    Protected WithEvents SqlConn As System.Data.SqlClient.SqlConnection
    Protected WithEvents SqlComm As System.Data.SqlClient.SqlCommand
    Protected WithEvents File1 As System.Web.UI.HtmlControls.HtmlInputFile

#Region " Web Form Designer Generated Code "

    'This call is required by the Web Form Designer.
    <System.Diagnostics.DebuggerStepThrough()> Private Sub InitializeComponent()
        Me.SqlConn = New System.Data.SqlClient.SqlConnection()
        Me.SqlComm = New System.Data.SqlClient.SqlCommand()

    End Sub

    Private Sub Page_Init(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Init
       Form Designer
       InitializeComponent()
    End Sub

#End Region

    Private Sub Page_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
    End Sub

    Private Sub cmdupload_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cmdupload.Click
        Dim image As System.Drawing.Image, newimage As System.Drawing.Image
        Dim callb As System.Drawing.Image.GetThumbnailImageAbort
        Dim f As System.IO.File, fs As System.IO.FileStream
        Dim temppath As String
        Dim bigdata As Byte(), smalldata As Byte()   '大图片数据、小图片数据
        Dim pic As System.Data.SqlClient.SqlParameter, picsmall As System.Data.SqlClient.SqlParameter
        '检察上传文件是否合标准,check函数是我根据网站需要写的了
        If check(File1.PostedFile.FileName) <> "ok" Then
            Response.Write(check(File1.PostedFile.FileName))
            Exit Sub
        End If
        '设置临时路径，为了防止多用户访问时的冲突，设了一个application对象
        If Application("image") = "" Then
            Application("image") = 0
        End If
        Application.Lock()
        temppath = Server.MapPath(CStr(Application("image")))  '临时路径
        Application("image") = Application("image") + 1
        Application.UnLock()
        '读取图片的数据
        ReDim bigdata((Me.File1.PostedFile.InputStream.Length)
        Me.File1.PostedFile.InputStream.Read(bigdata, 0, UBound(bigdata))  '将原图片数据读到bigdata中
        '改变图片的大小
        image = System.Drawing.Image.FromStream(Me.File1.PostedFile.InputStream)
'newimage里面的size也可另外设置，我只用了80*60和60*80两种
        If image.Width > image.Height Then
            newimage = image.GetThumbnailImage(80, 60, callb, New System.IntPtr(0))
        Else
            newimage = image.GetThumbnailImage(60, 80, callb, New System.IntPtr(0))
        End If
        image.Dispose()
'将新图片及图片变小后存到临时路径中
        newimage.Save(temppath, System.Drawing.Imaging.ImageFormat.Jpeg)
        newimage.Dispose()
'读取临时文件数据到smalldata中
        fs = New System.IO.FileStream(temppath, IO.FileMode.Open, IO.FileAccess.Read)
        ReDim smalldata(fs.Length)
        fs.Read(smalldata, 0, UBound(smalldata))
        fs.Close()
'上述获得小图片的方法我原本想用system.io.memorystream的，可是行不通：代码如下：
'dim m as system.io.memorystream
'm=new system.io.memorystream()
'newimage.save(m,System.Drawing.Imaging.ImageFormat.Jpeg)
'redim smalldata(m.length)
'm.read(smalldata,0,m.length)
'可是上述方法读出来的smalldata全是空的，不知道原因，请指教
        '删除临时文件
        If f.Exists(temppath) Then
            f.Delete(temppath)
        End If
        '将数据加入数据库中
'由于数据库中有image字段，我用sql插不进去，就用一个存储过程
'请教各位大虾用sql语句插入有image字段的表该怎么写
'用insert into talbe(pic,picsmall) values("&bigdata&","&smalldata&")这样不行，用'"&bigdata&"'也不行呀！
        SqlConn = New System.Data.SqlClient.SqlConnection(connstr)  '可自己设置connstr连接数据库服务器
        SqlComm = New System.Data.SqlClient.SqlCommand()
        SqlComm.CommandType = CommandType.StoredProcedure
        SqlComm.CommandText = "dbo.image"
        pic = New System.Data.SqlClient.SqlParameter("pic", SqlDbType.Image)
        pic.Value = bigdata
        picsmall = New System.Data.SqlClient.SqlParameter("picsmall", SqlDbType.Image)
        picsmall.Value = smalldata
        SqlComm.Parameters.Add(pic)
        SqlComm.Parameters.Add(picsmall)
        SqlComm.Connection = SqlConn
        SqlComm.Connection.Open()
        SqlComm.ExecuteNonQuery()
        SqlComm.Connection.Close()
        SqlComm.Dispose()
        SqlConn.Dispose()
    End Sub
End Class

dbo.image存储过程如下:
create proc dbo.image
  pic image,
  picsmall image
as
  insert into table(pic,picsmall) values (pic,picsmall)