asp.net|上传|上传图片|缩略图在ASP.NET中上传图片并生成缩略图的C#源码

　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里轻松实炙趼酝?lt;/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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