C # Implementation of File upload and download function Example _c# Tutorial

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1. C # File Upload

Create a myupload.htm page for testing

<form name= "Form1" method= "Post" action= "uploadfile.aspx" id= "Form1" enctype= "Multipart/form-data"  
> 
  <input type= "File" id= "txtfile" name= "Picfile"/></br> "<input type=" 
  submit "value=" Upload "/> 

Create the Uploadfile.aspx file and type the following code in UploadFile.aspx.cs:

Random rnd = new Random ();   Generate random number private string _directory = @ "/file/uploadfile"; 
      Directory protected void Page_Load (object sender, EventArgs e) {try {if (Requestfilescount > 0) { 
      Determine file size int length = Requestfiles[0]contentlength; 
        if (length > 1048576) {responsewrite ("file is greater than 1M, cannot be uploaded"); 
      Return 
      } String type = Requestfiles[0]contenttype; 
      String fileext = Pathgetextension (requestfiles[0]filename) ToLower (); 
      can only upload pictures, filter the file type can not be uploaded string filefilt = "Gif|jpg|php|jsp|jpeg|png|"; if (Filefiltindexof (Fileext) <=-1) {Responsewrite ("Sorry!)" Please upload pictures!! 
        "); 
      Return else {string fileName = Servermappath (_directory) + "\" + datetimenowtostring ("YYYYMMDDHHMMSSFF 
        F ") + Rndnext (+) ToString () + Fileext; 
        Requestfiles[0]saveas (FileName); Responsewrite ("Upload success!") 
      "); catch {throW new Exception (); 
 } 
}

2. C # File download

To create the downloadfile.aspx, type the following method DownloadFile.aspx.cs:

<summary>///C # file download///</summary>///<param name= "filename" ></param> public void Mydow 
  Nload (string filename) {string path = Servermappath ("/file/" +filename); if (! FileExists (Path)) {Responsewrite ("Sorry!)" File does not exist!! 
    "); 
  Return 
  } systemiofileinfo File = new Systemiofileinfo (path); String filefilt= "asp|aspx|php|jsp|ascx|config|asa|"; 
  Non-downloadable files, be sure to filter the clean string filename = filename; 
  String fileext = Filenamesubstring (Filenamelastindexof ("")) Trim () ToLower (); if (Filefiltindexof (fileext)!=-1) {responsewrite ("Sorry!)" This class file is not allowed to download!! 
  "); 
    else {responseclear (); Responseaddheader ("Content-disposition", "attachment; 
    Filename= "+ httputilityurlencode (fileName)); 
    Responseaddheader ("Content-length", filelengthtostring ()); 
    Responsecontenttype = getContentType (Httputilityurlencode (Fileext)); 
    Responsewritefile (Filefullname); 
  Responseend (); }///<summary>///get download type///</summary>///<param name= "Fileext" ></param>///<returns></returns> public string Getcontenttyp 
  E (String fileext) {string ContentType; 
    Switch (fileext) {case "asf": ContentType = "video/x-ms-asf"; Case "avi": ContentType = "Video/avi"; 
    Break Case "Doc": ContentType = "Application/msword"; 
    Break Case "Zip": ContentType = "Application/zip"; 
    Break Case "xls": ContentType = "Application/vndms-excel"; 
    Break Case "gif": ContentType = "Image/gif"; 
    Break Case "jpg": ContentType = "Image/jpeg"; 
    Break Case "JPEG": ContentType = "Image/jpeg"; 
    Break Case "wav": ContentType = "Audio/wav"; 
    Break Case "MP3": ContentType = "Audio/mpeg3"; 
    Break Case "mpg": ContentType = "Video/mpeg"; 
    Break Case "MEPG": ContentType = "Video/mpeg"; 
    Break Case "RTF": ContentType = "Application/rtf"; 
    Break CasE "html": ContentType = "text/html"; 
    Break Case "htm": ContentType = "text/html"; 
    Break Case "TXT": ContentType = "Text/plain"; 
    Break 
      Default:contenttype = "Application/octet-stream"; 
  Break 
return ContentType;  }

* How to get the ContentType property of an existing file

<summary> 
///Get contenttype properties of existing Files 
///</summary> 
///<param name= "filename" >< /param> 
///<returns></returns> public 
string Getfilecontenttype (string filename) 
{ 
  string[] Array = filenamesplit ('); 
  string result = Stringempty; 
  string suffix = "" + array[arraylength-1]; 
  Microsoftwinregistrykey RG = microsoftwinregistryclassesrootopensubkey (suffix); 
  Object obj = Rggetvalue ("Content Type"); 
  result = obj!= null? Objtostring (): Stringempty; 
  Rgclose (); 
  return result; 
}  

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