ASP. NET Image Upload instance (with source code ),
Because the image upload function is required, it takes some time to find relevant information on the Internet, as shown below:
The following are the solutions and uploaded images:
The following code is used:
1. interface code
<% @ Page Language = "C #" AutoEventWireup = "true" CodeBehind = "UploadPic. aspx. cs" Inherits = "Pic_Try.UploadPic" %> <! DOCTYPE html PUBLIC "-// W3C // dtd xhtml 1.0 Transitional // EN "" http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd "> <Html xmlns =" http://www.w3.org/1999/xhtml "> <Head runat =" server "> <title> upload and display images </title> <style type =" text/css ">. pic_text {color: Red ;}. pic_label {color: Gray; margin-top: 5px; margin-bottom: 5px ;}. pic_image {margin: 5px ;} </style>
2. Background code
Using System; using System. collections. generic; using System. linq; using System. web; using System. web. UI; using System. web. UI. webControls; using System. IO; using System. security. cryptography; using System. web. security; namespace Pic_Try {public partial class UploadPic: System. web. UI. page {protected void Page_Load (object sender, EventArgs e) {} protected void btn_upload_Click (object sender, EventArgs e ){ Boolean fileOk = false; if (pic_upload.HasFile) // verify whether the file contains the file {// obtain the file extension and convert it to lowercase string fileExtension = Path. getExtension (pic_upload.FileName ). toLower (); // verify whether the image format of the uploaded file is fileOk = IsImage (fileExtension); if (fileOk) {// check the size of the uploaded file, the limit file cannot exceed 8 Mb if (pic_upload.PostedFile.ContentLength <8192000) {string filepath = "/images/"; if (Directory. exists (Server. mapPath (filepath) = false) // create a file folder if it does not exist {Directory. createDirectory (Server. mapPath (filepath);} string virpath = filepath + CreatePasswordHash (pic_upload.FileName, 4) + fileExtension; // This is the virtual path stored on the Server string mappath = Server. mapPath (virpath); // converts it to the physical path pic_upload.PostedFile.SaveAs (mappath) on the server; // saves the image // displays the image pic. imageUrl = virpath; // The lbl_pic.Text = "";} else {pic. imageUrl = ""; lbl_pic.Text = "the file size exceeds 8 Mb! Please select again! ";}} Else {pic. ImageUrl =" "; lbl_pic.Text =" the type of the file to be uploaded is incorrect! Please select again! ";}} Else {pic. ImageUrl =" "; lbl_pic.Text =" select the image to upload! ";}} /// <Summary> /// verify whether the specified image format is used. /// </summary> /// <param name = "str"> </param> /// <returns> </returns> public bool IsImage (string str) {bool isimage = false; string thestr = str. toLower (); // only jpg and GIF image string [] allowExtension = {". jpg ",". gif ",". bmp ",". png "}; // perform a pair of for (int I = 0; I <allowExtension. length; I ++) {if (thestr = allowExtension [I]) {isimage = true; break ;}} return isimage ;} /// <summary> /// create a random salt value of the specified length /// </summary> public string CreateSalt (int saltLenght) {// generate an encrypted random number RNGCryptoServiceProvider rng = new RNGCryptoServiceProvider (); byte [] buff = new byte [saltLenght]; rng. getBytes (buff); // returns the return Convert string of a Base64 random number. toBase64String (buff);} // <summary> // return the encrypted string /// </summary> public string CreatePasswordHash (string pwd, int saltLenght) {string strSalt = CreateSalt (saltLenght); // connect the password to Salt string saltAndPwd = String. concat (pwd, strSalt); // hash the password string hashenPwd = FormsAuthentication. hashPasswordForStoringInConfigFile (saltAndPwd, "sha1"); // convert it to lowercase characters and extract the first 16 strings hashenPwd = hashenPwd. toLower (). substring (0, 16); // return the hash value return hashenPwd ;}}}
3. Finally, to prevent the upload of large file images from returning an error, add configuration in the configuration file
<? Xml version = "1.0" encoding = "UTF-8"?> <! -- How to configure ASP. NET application details --> <configuration> <system. web> <compilation debug = "true" targetFramework = "4.0"/>
Automatic ASP. NET Image Upload and partial refresh displaySource code download.
I hope you will like this article.
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