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.EventArgse) 
{
  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);
  }
 }
}
</FONT>
</FONT>
</FONT>

<FONT color=#ff0000 size=4>
======================================================================================</FONT>

<FONT size=4>
功能：1。把图片文件(JPG GIF PNG)上传，2。保存到指定的路径（在web.config中设置路径，以文件的原有格式保存），3。并自动生成指定宽度的（在web.config中设置宽度）4。和指定格式的（在web.config中指定缩略图的格式）5。和原图比例相同的缩略图(根据宽度和原图的宽和高计算所略图的高度)6。可以判断是否已经存在文件7。如果不覆盖，则给出错误8。如果选中"覆盖原图"checkbox，则覆盖原图。9。可以根据要求，在webform上设置1个以上的file input和相应的checkbox10。并在文件上传完毕后，显示原图的文件名，尺寸，字节，和11。缩略图的文件名尺寸。12。缩略图的文件名格式：原图+"_thumb."+指定格式，如：test.jpg_thumb.gif,以便于管理。--------------------public void UploadFile(object sender, System.EventArgs e)
{
string imgNameOnly, imgNameNoExt, imgExt;
string imgThumbnail;
int erroNumber = 0;
System.Drawing.Image oriImg, newImg;
string strFePicSavePath = ConfigurationSettings.AppSettings["FePicSavePath"].ToString();
string strFePicThumbFormat = ConfigurationSettings.AppSettings["FePicThumbFormat"].ToString().ToLower();
int intFeThumbWidth = Int32.Parse(ConfigurationSettings.AppSettings["FePicThumbWidth"]);
string fileExt;
StringBuilder picInfo = new StringBuilder();
if(Page.IsValid)
{
for(int i = 0;
i < Request.Files.Count;
 i++)
{
HttpPostedFile PostedFile = Request.Files[i];
fileExt = (System.IO.Path.GetExtension(PostedFile.FileName)).ToString().ToLower();
imgNameOnly = System.IO.Path.GetFileName(PostedFile.FileName);
if(fileExt == ".jpg" || fileExt == ".gif" || fileExt == ".png")
{
if(System.IO.File.Exists(strFePicSavePath + imgNameOnly) && (checkboxlistRewrite.Items[i].Selected == false))
{
erroNumber = erroNumber + 1;
picInfo.Append("<b>错误：</b>文件("+ (i+1) +") " + imgNameOnly + " 已经存在，请修改文件名<br/>" );
}
}
else
{
erroNumber = erroNumber + 1;
picInfo.Append("<b>
错误：</b>
文件("+ (i+1) +") " + imgNameOnly + " 扩展名 " + fileExt + " 不被许可<br/>" );
}
}
if(erroNumber >
 0)
{
picInfo.Append("<font color=red>全部操作均未完成，请修改错误，再进行操作</font><br/>");
}
else
{
for(int i = 0;
i < Request.Files.Count;
 i++)
{
HttpPostedFile PostedFile = Request.Files[i];
imgNameOnly = System.IO.Path.GetFileName(PostedFile.FileName);
imgNameNoExt = System.IO.Path.GetFileNameWithoutExtension(PostedFile.FileName);
imgExt = System.IO.Path.GetExtension(PostedFile.FileName).ToString().ToLower();
oriImg = System.Drawing.Image.FromStream(PostedFile.InputStream);
newImg = oriImg.GetThum
4000
bnailImage(intFeThumbWidth, intFeThumbWidth * oriImg.Height/oriImg.Width,null,new System.IntPtr(0));
switch(imgExt)
{
//case ".jpeg":case ".jpg":oriImg.Save(strFePicSavePath + imgNameOnly , System.Drawing.Imaging.ImageFormat.Jpeg);
break;
case ".gif":oriImg.Save(strFePicSavePath + imgNameOnly , System.Drawing.Imaging.ImageFormat.Gif);
break;
case ".png":oriImg.Save(strFePicSavePath + imgNameOnly , System.Drawing.Imaging.ImageFormat.Png);
break;
}
//oriImg.Save(ConfigurationSettings.AppSettings["FePicSavePath"] + imgNameNoExt + ".jpg", System.Drawing.Imaging.ImageFormat.Jpeg);
switch(strFePicThumbFormat)
{
//jpeg format can get the smallest file size, and the png is the largest size//case "jpeg":case "jpg":newImg.Save(strFePicSavePath + imgNameOnly + "_thumb.jpg",System.Drawing.Imaging.ImageFormat.Jpeg);
imgThumbnail = imgNameOnly + "_thumb.jpg";
break;
case "gif":newImg.Save(strFePicSavePath + imgNameOnly + "_thumb.gif",System.Drawing.Imaging.ImageFormat.Gif);
imgThumbnail = imgNameOnly + "_thumb.gif";
break;
case "png":newImg.Save(strFePicSavePath + imgNameOnly + "_thumb.png",System.Drawing.Imaging.ImageFormat.Png);
imgThumbnail = imgNameOnly + "_thumb.png";
break;
default:newImg.Save(strFePicSavePath + imgNameOnly + "_thumb.jpg",System.Drawing.Imaging.ImageFormat.Jpeg);
imgThumbnail = imgNameOnly + "_thumb.jpg";
break;
}
//switchpicInfo.Append("<b>文件　名：</b>" + imgNameOnly + " ( " + oriImg.Width + " x " + oriImg.Height + " ) " + PostedFile.ContentLength/1024 + "KB<br/>");
picInfo.Append("<b>缩略图名：</b>" + imgThumbnail + " ( " + newImg.Width + " x " + newImg.Height + " )<br/><br/>");
oriImg.Dispose();
newImg.Dispose();
}
//forpicInfo.Append("<font color=red>所有操作成功</font><br/>");
}
// if erronumber = 0}
else
{
picInfo.Append("<font color=red>有错误，请检查。操作未成功</font><br/>");
}
lblPicInfo.Text = picInfo.ToString();
}