在ASP.NET里轻松实现缩略图
<%@ Page Language="vb" AutoEventWireup="false" Codebehind="Thumbnail.aspx.cs"
Inherits="aspxWeb.Thumbnail" %>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML>
<HEAD>
<title>在ASP.NET里轻松实现缩略图</title>
<meta content="Microsoft Visual Studio.NET 7.0" name="GENERATOR">
<meta content="Visual Basic 7.0" name="CODE_LANGUAGE">
<meta content="JavaScript" name="vs_defaultClientScript">
<meta content="http://schemas.microsoft.com/intellisense/ie5" name="vs_targetSchema">
</HEAD>
<body MS_POSITIONING="GridLayout">
<asp:Label id="Label1" runat="server"></asp:Label>
<form id="Form1" method="post" runat="server" enctype="multipart/form-data">
<INPUT type="file" name="file" width="600"><br><br>
<asp:Button id="Button1" runat="server"></asp:Button>
</form>
</body>
</HTML>
Inherits="aspxWeb.Thumbnail" %> <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> <HTML> <HEAD> <title>在ASP.NET里轻松实现缩略图</title> <meta content="Microsoft Visual Studio.NET 7.0" name="GENERATOR"> <meta content="Visual Basic 7.0" name="CODE_LANGUAGE"> <meta content="JavaScript" name="vs_defaultClientScript"> <meta content="http://schemas.microsoft.com/intellisense/ie5" name="vs_targetSchema"> </HEAD> <body MS_POSITIONING="GridLayout"> <asp:Label id="Label1" runat="server"></asp:Label> <form id="Form1" method="post" runat="server" enctype="multipart/form-data"> <INPUT type="file" name="file" width="600"><br><br> <asp:Button id="Button1" runat="server"></asp:Button> </form> </body> </HTML> 后台代码 using System; using System.Collections; using System.ComponentModel; using System.Data; using System.Drawing; using System.Web; using System.Web.SessionState; using System.Web.UI; using System.Web.UI.WebControls; using System.Web.UI.HtmlControls; using System.IO; using System.Drawing.Imaging; namespace eMeng.Exam 
{ 
/// <summary> 
/// Thumbnail 的摘要说明。 
/// </summary> public class Thumbnail : System.Web.UI.Page { protected System.Web.UI.WebControls.Label Label1; protected System.Web.UI.WebControls.Button Button1; private void Page_Load(object sender, System.EventArgs e) { // 在此处放置用户代码以初始化页面 Label1.Text = "<h3>在ASP.NET里轻松实现缩略图</h3>"; Button1.Text = "上载并显示缩略图"; } #region Web 窗体设计器生成的代码 override protected void OnInit(EventArgs e) { // // CODEGEN: 该调用是 ASP.NET Web 窗体设计器所必需的。 // InitializeComponent(); base.OnInit(e); } /// <summary> /// 设计器支持所需的方法 - 不要使用代码编辑器修改 /// 此方法的内容。 /// </summary> private void InitializeComponent() { this.Button1.Click += new System.EventHandler(this.Button1_Click); this.Load += new System.EventHandler(this.Page_Load); } #endregion private void Button1_Click(object sender, System.EventArgs e) { HttpFileCollection MyFileColl = HttpContext.Current.Request.Files; HttpPostedFile MyPostedFile = MyFileColl[0]; if (MyPostedFile.ContentType.ToString().ToLower().IndexOf("image") < 0) { Response.Write("无效的图形格式。"); return; } GetThumbNail(MyPostedFile.FileName, 100, 100, MyPostedFile.ContentType.ToString(), false, MyPostedFile.InputStream); } private System.Drawing.Imaging.ImageFormat GetImageType(object strContentType) { if ((strContentType.ToString().ToLower()) == "image/pjpeg") { return System.Drawing.Imaging.ImageFormat.Jpeg; } else if ((strContentType.ToString().ToLower()) == "image/gif") { return System.Drawing.Imaging.ImageFormat.Gif; } else if ((strContentType.ToString().ToLower()) == "image/bmp") { return System.Drawing.Imaging.ImageFormat.Bmp; } else if ((strContentType.ToString().ToLower()) == "image/tiff") { return System.Drawing.Imaging.ImageFormat.Tiff; } else if ((strContentType.ToString().ToLower()) == "image/x-icon") { return System.Drawing.Imaging.ImageFormat.Icon; } else if ((strContentType.ToString().ToLower()) == "image/x-png") { return System.Drawing.Imaging.ImageFormat.Png; } else if ((strContentType.ToString().ToLower()) == "image/x-emf") { return System.Drawing.Imaging.ImageFormat.Emf; } else if ((strContentType.ToString().ToLower()) == "image/x-exif") { return System.Drawing.Imaging.ImageFormat.Exif; } else if ((strContentType.ToString().ToLower()) == "image/x-wmf") { return System.Drawing.Imaging.ImageFormat.Wmf; } else { return System.Drawing.Imaging.ImageFormat.MemoryBmp; } } private void GetThumbNail(string strFileName, int iWidth, int iheight, string strContentType, bool blnGetFromFile, System.IO.Stream ImgStream) { System.Drawing.Image oImg; if (blnGetFromFile) { oImg = System.Drawing.Image.FromFile(strFileName); } else { oImg = System.Drawing.Image.FromStream(ImgStream); } oImg = oImg.GetThumbnailImage(iWidth, iheight, null, IntPtr.Zero); string strGuid = System.Guid.NewGuid().ToString().ToUpper(); string strFileExt = strFileName.Substring(strFileName.LastIndexOf(".")); Response.ContentType = strContentType; MemoryStream MemStream = new MemoryStream(); oImg.Save(MemStream, GetImageType(strContentType)); MemStream.WriteTo(Response.OutputStream); } } } 
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