Webform (File upload)

1.HTML Encoding:

<input type= "File"/>

2. Control: FileUpload

It is used to select files to upload, and a button is required to upload the selected files to the server

String path = "images/" + fileupload1.filename;
Fileupload1.saveas (Server.MapPath (path));

Optimization 1: The file retains its original name and suffix

String path = "images/" + fileupload1.filename;

Optimization 2: Prevent duplicate names, or multiple people at the same time upload the same name file

String path = "images/" + DateTime.Now.ToString ("Yyyymmddhhssmmms") + request.cookies["Ures"]. Value + fileupload1.filename;

Optimization 3: Can upload large files, default is 4MB,4096KB
Method: Expansion

Add the following sentence to the system.web tag in Web. config:

Note: Do not expand too much, because if multiple people upload large files at the same time, it may cause server memory overflow, causing the server to crash.

Optimization 4: Exceeding the size of the upload request, preventing uploading and prompting the file to be too large
C # Side resolution:

if (fileupload1.postedfile.contentlength> (1024*1024*10)) {labei1.text= "file more than 10M, do not upload such a large! "; return;}

C # End is bad, because if the file exceeds the maximum length, the C # end is limited, and the program crashes directly

JS End:

document.getElementById ("Button1"). onclick = function () {        //Remove the upload element        var fi1 = document.getElementById (" FileUpload1 ");        Determine if there is a selected file        if (fi1.value.length <= 0) {            alert (' Please select a file to upload! ');            return false;        }        else {            //Verify that the selected file length meets the condition            if (fi1.files[0].size > (1024x768 *))            {                alert (' file is too large to allow uploading! ');                return false;}}    ;

Optimization 5: Limit the types of files that can be selected

In the FileUpload property, add accept= ". Jpg,.jpeg,.png"

Breakpoint Continuation:

 1 using System;  2 using System.Data;  3 using System.Configuration;  4 using System.Collections;  5 using System.Web;  6 using System.Web.Security;  7 using System.Web.UI;  8 using System.Web.UI.WebControls; 9 using System.Web.UI.WebControls.WebParts; Ten using System.Web.UI.HtmlControls; One using System.IO; Public partial class DFile:System.Web.UI.Page {protected void Page_Load (object sender, EventArgs e) 15 {16} protected void Linbtndfile_click (object sender, EventArgs e) 18 {19//Create one-bit array [byte[] buffer = new byte[10240]; 21 Specifies the path to the file to download. String filePath = @ "D:\-ji-ai-nook. rar"; 23//or take file name including extension of string filename = Path.getfilename (FilePath); Stream fileStream = null; $ try 27 {28//Open File FileStream = new FileStream (FilePath, FileMode.Open, FileAccess.Read, FileShare.Read); Se. Clear (); 31//Get file Size: FileSize = filestream.length; A long sum = 0; if (request.headers["Range"] = null) {Response.statuscode = 206;//HTTP returned to the clientAn integer that outputs the state. The default value is 200. PNS sum = long. Parse (request.headers["Range"). Replace ("bytes=", ""). Replace ("-", "")); (sum! = 0) Response.AddHeader ("Content-range", "bytes" + sum.) ToString () + "-" + ((long) (fileSize)). ToString () + "/" + filesize.tostring ()); 42} 43//Get partial HTTP header information for Response.AddHeader ("Content-length", ((Long) (Filesize-sum)). ToString ()); Response.ContentType = "Application/octet-stream"; 46//Get File Source Response.AddHeader ("content-disposition", "attachment; Filename= "+ Httputility.urlencode (Request.ContentEncoding.GetBytes (fileName)); //Response.Flush (); filestream.position = sum; Sets the current flow position of fileSize = filesize-sum; 51//When the size of the file is greater than 0 is into the loop of the (FileSize > 0) 53 {54//Determine if the client is still connected to the server if (response.isclientconnected) 56 {57//Get Slow The total number of bytes in the flush area. filestream.read int length = n/A (buffer, 0, 10240); 59//Write Data Response.OutputStream.Write (buffer, 0, length); 61//The output of the buffer is sent to client Response.Flush (); Buffer = new byte[10240]; FileSize = FilesizE-length;  $67} (68) (if the user disconnects and exits the loop, fileSize =-1;) (Exception ex) ("Error: "+ Ex. Message);  $80 {81//Close file Filestream.close (); response.end} (); 85} 86} 87---  }

Webform (file upload)