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This article mainly introduces ASP.NET MVC in-depth understanding of file upload example analysis, the article introduces in great detail, has a certain reference value, interested friends must read it!

Deep upload

Once again, we do not discuss too much about uploading, such as showing upload progress. If we have such components, we only need to implement the core piece.

We can imagine a scenario like this: for example, in a blog park, every blogger can upload files such as pictures, scripts, etc., and we can create files uploaded by each gardener through the name of the gardener. Next, let's implement such a scenario.

Since it is corresponding to the name of the blog to create a file, that is, you need a class like the corresponding blog. As follows:

Public class BlogSample {public string UserName {get; set;} public string Id {get; set;}}

We create a folder by the name of the blog and create a subfolder under this folder with a unique Id, and store the uploaded files in the attachment (atttachment) under the Id folder. Next we need to sort out the whole process of uploading files. Is it possible to upload the files directly to the corresponding folder? this is obviously not optimal. When the upload is interrupted, the files created in the folder are not complete, then they are junk files, and we directly create a temporary file first. Even if the upload fails, we can regularly clean up the temporary files, that is, junk files, if not interrupted. When the upload is complete, move the temporary files to our corresponding folder. It is obvious from the fact that we downloaded the file that we did the same thing. Next we begin to implement.

(1) We give a UploadManager static class about uploading. We can write down the name of the uploaded folder or customize the uploaded folder name through the configuration file.

Static UploadManager () {/ / get upload folder if (String.IsNullOrWhiteSpace (WebConfigurationManager.AppSettings ["UploadFolder"])) UploadFolderRelativePath = @ "~ / upload"; else UploadFolderRelativePath = WebConfigurationManager.AppSettings ["UploadFolder"]; UploadFolderPhysicalPath = HostingEnvironment.MapPath (UploadFolderRelativePath); if (! Directory.Exists (UploadFolderPhysicalPath)) Directory.CreateDirectory (UploadFolderPhysicalPath);}

The above has shown that you can customize the upload folder in the configuration file (give the upload virtual path), for example:

(2) the core method of saving files

[SuppressMessage ("Microsoft.Usage", "CA2202:Do not dispose objects multiple times")] public static bool SaveFile (Stream stream, string fileName, string userName, string guid) {string tempPath = string.Empty, targetPath = string.Empty; try {string tempFileName = GetTempFilePath (fileName); if (userName! = null) {var contentType = userName; var contentId = guid; tempPath = GetTempFilePath (tempFileName); targetPath = GetTargetFilePath (fileName, contentType, contentId, string.Empty, FilesSubdir) / / if the subfolder of the upload folder does not exist, create var file = new FileInfo (targetPath); if (file.Directory! = null & &! file.Directory.Exists) file.Directory.Create (); using (FileStream fs = File.Open (tempPath, FileMode.Append)) {if (stream.Length > 0) {SaveFile (stream, fs);} fs.Close () } / / move the temporary file to the target file File.Move (tempPath, targetPath);}} catch (Exception) {/ / if the upload error occurs, delete the file uploaded to the folder if (File.Exists (targetPath)) File.Delete (targetPath); / / delete the temporary file if (File.Exists (tempPath)) File.Delete (tempPath); return false } finally {/ / Delete temporary file if (File.Exists (tempPath)) File.Delete (tempPath);} return true;}

(3) Loop read stream to file stream

/ public static void SaveFile (Stream stream, FileStream fs) {var buffer = new byte [4096]; int bytesRead; while ((bytesRead = stream.Read (buffer, 0, buffer.Length)! = 0) {fs.Write (buffer, 0, bytesRead);}}

(4) start writing test data and call the method:

Var testSample = new BlogSample () {UserName = "xpy0928", Id = Guid.NewGuid (). ToString ("N")}; if (ModelState.IsValid) {var fileName = bModel.BlogPhoto.FileName; var success = UploadManager.SaveFile (bModel.BlogPhoto.InputStream, fileName, testSample.UserName, testSample.Id); if (! success) {/ / TODO (your code)} / / var filePath = Server.MapPath (string.Format ("~ / {0}", "File")) / / bModel.BlogPhoto.SaveAs (Path.Combine (filePath, fileName); ModelState.Clear ();}

Next, let's test it by uploading an 84m file to see the effect (wait a moment, the file is a little large).

Sorry, to my great disappointment, unlike yesterday's error, today's error is: exceeds the maximum request length. Let's take a look at what we said yesterday, my IIS is 10.0, that is, on IIS 7 +, it should be no problem to set it that way yesterday. Is it related to another setting? let's take a look at the configuration in the configuration file.

If it is not set, will it make an error if it exceeds its default setting of 28.6m? let's set it to 2G again.

Well, the upload was successful and the above error did not occur.

Conclusion

In this section, we talked about the use of streams to deal with large files, but there is still a small problem, and we will summarize it again yesterday:

(1) in IIS 5 and IIS 6, the default maximum file upload size is 4 megabytes. When the uploaded file size exceeds 4 megabytes, you will get an error message, but we set the file size as shown below.

(2) in IIS 7 upload, the maximum default file upload is 28.6 megabytes. When the default setting size is exceeded, you will also get an error message, but we can set the file upload size as below (also set as above).

The above is all the contents of the article "ASP.NET MVC's in-depth understanding of the sample Analysis of File upload". Thank you for reading! Hope to share the content to help you, more related knowledge, welcome to follow the industry information channel!

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