c#多图片上传并生成缩略图的实例代码

前端技术 2023/09/08 .NET

前台代码:

复制代码 代码如下:


 <%@ Page Language=\"C#\" AutoEventWireup=\"true\" CodeFile=\"upload.aspx.cs\" Inherits=\"upload\" %>

 <!DOCTYPE html>

 <html xmlns=\"http://www.w3.org/1999/xhtml\">
 <head runat=\"server\">
     <meta http-equiv=\"Content-Type\" content=\"text/html; charset=utf-8\" />
     <title></title>
     <style type=\"text/css\">
         li
         {
             list-style: none;
             padding-top: 10px;
         }
     </style>
     <script type=\"text/javascript\" src=\"js/jquery-1.6.2.min.js\"></script>
     <script type=\"text/javascript\">
         function ValidImage(id, msg) {
             $(id).parent().append(\"<span>\" + msg + \"</span>\");
             return false;
         }
     </script>
 </head>
 <body>
     <form id=\"form1\" runat=\"server\" enctype=\"multipart/form-data\" method=\"post\">
         <div>
                       <ul>
                 <li>
                     <input type=\"file\" id=\"upload1\" name=\"upload\" />
                 </li>
                 <li>
                     <input type=\"file\" id=\"upload2\" name=\"upload\" />
                 </li>
                 <li>
                     <input type=\"file\" id=\"upload3\" name=\"upload\" />
                 </li>
                 <li>
                     <input type=\"file\" id=\"upload4\" name=\"upload\" /></li>
                 <li>
                     <input type=\"file\" id=\"upload5\" name=\"upload\" />

                 </li>
                 <li>
                     <input type=\"submit\" id=\"btnPostFile\" runat=\"server\" onserverclick=\"btnPostFile_ServerClick\" value=\"开始上传\" />
                 </li>
             </ul>
         </div>
     </form>
 </body>
 </html>

前台就是几个控件和一个ValidImage方法。

后台代码：

复制代码 代码如下:


  protected void btnPostFile_ServerClick(object sender, EventArgs e)
     {
         string filePath = Server.MapPath(\"/uploadImg\");
         const int size = 5242880;
         if (!Directory.Exists(filePath))
         {
             Directory.CreateDirectory(filePath);
         }
         if (Request.Files.Count > 0)
         {
             for (int i = 0; i < Request.Files.Count; i++)
             {
                 HttpPostedFile postFile = Request.Files[i];
                 string uploadFileID = string.Format(\"#upload{0}\", i + 1);  //当前的上传控件ID,因为jquery要调用就加了#
                 string msg = null;                 //提示信息
                 if (postFile.FileName.Trim().Length <= 0)
                 {
                     continue;
                 }
                 if (postFile.ContentLength > size)
                 {
                     msg = \"文件太大\";
                     Page.ClientScript.RegisterStartupScript(GetType(), \"\", \"ValidImage(\" + uploadFileID + \",\" + msg + \")\", true);//将提示信息发送到客户端
                     continue;
                 }
                 string savePath = Path.Combine(filePath, postFile.FileName);        //图片的保存地址
                 if (!File.Exists(savePath))
                 {
                     postFile.SaveAs(Path.Combine(filePath, postFile.FileName));     //如果文件不存在就保存
                 }
                 else
                 {
                     msg = \"文件\" + postFile.FileName + \"已经存在\";
                     Page.ClientScript.RegisterStartupScript(GetType(), \"\", \"ValidImage(\" + uploadFileID + \",\" + msg + \")\", true);//将提示信息发送到客户端
                     continue;
                 }
                 if (IsImg(savePath))            //通过IsImg方法验证文件是否是图片，或者格式是否正确
                 {
                     SmallImg(postFile.InputStream, postFile.FileName);
                 }
                 else
                 {
                     msg = \"只能上传JGP、PNG类型的图片，请检查文件格式是否正确\";
                     Page.ClientScript.RegisterStartupScript(GetType(), \"\", \"ValidImage(\" + uploadFileID + \",\" + msg + \")\", true);//将提示信息发送到客户端
                     File.Delete(savePath);  //如果不是图片就删除
                 }
             }
         }
     }

复制代码 代码如下:

  #region 验证上传文件的格式
     /// <summary>
     /// 验证上传文件是否是图片
     /// </summary>
     /// <param name=\"FilePath\">文件的保存路径</param>
     /// <returns></returns>
     private bool IsImg(string FilePath)
     {
         using (FileStream fs = new FileStream(FilePath, FileMode.Open, FileAccess.Read))
         {
             bool result = false;
             BinaryReader br = new BinaryReader(fs, System.Text.Encoding.UTF8);
             string strImg = \"\";
             byte buffer;
             try
             {
                 buffer = br.ReadByte();
                 strImg = buffer.ToString();
                 buffer = br.ReadByte();
                 strImg += buffer.ToString();
             }
             catch
             {
                 fs.Close();
                 br.Close();

             }
             if (strImg == \"255216\" || strImg == \"13780\")//说明255216是jpg;7173是gif;6677是BMP,13780是PNG;7790是exe,8297是rar
             {
                 result = true;
             }
             return result;
         }
     }
     #endregion

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