如何从C＃或Javascript检查文件是否存在？

Question

We have a application hosted in some other server located in another country, I am going to use that application from different country, while using that application i want to check the user's machine local 'C' drive particular path is having that file is exist or not.

How to achieve this from C# or Javascript?

From the C#

byte[] contents = null;
if (File.Exists("C:\Program Files (x86)\Fruit\fruitList.txt"))
     {
        using (FileStream fileStream = File.OpenRead(scannedFile))
        {
               contents = new byte[fileStream.Length];
        }
     }

but that mentioned 'C' drive path is searching in IIS server only (where we hosted the application). But i want to check in client (user's) machine.

I couldn't find a code in Javascript.

Please help me, to achieve the expected result.

Thank you.

Answer 1

What you are attempting to do is not easily possible. JS will not work as it is blocked from accessing the user's client machine for security reasons. C# cannot access the client at all as it runs on the server.

The alternative is for the user to manually pick the required file from their machine using a <input type="file" /> then upload that file to your server for it to be processed and validated.

Failing that you could write a program which the user installs on their machine which provides methods for your website to retrieve information from the client - however this is an incredibly involved process.

Answer 2

You cant access the clients drive from the server side, would be a major security issue. You will have to ask the client to tell you if they have the file or not or find another work around. This is also whys its searching in IIS server, because it thinks you are looking for a local file. Hope this helps!

Answer 3

In a Website (C#) you will only have access to the files of the server because is the machine who is executing the application.

For Javascript who is execute in the client, that's not possible because client file access is not allowed by design, read this article:

Javascript Security

If you need this you have to develop an application to install in the client's PC and connect the server from this application, this is the only way, you will never have access to the client files since the browser.

Answer 4

Use this way

C#

var fileStream = new FileStream(filePath, FileMode.Open, FileAccess.Read);

Get the file extension from fileStream variable

Javascript:

<input id="File" type="file"/>

$("#File")[0].files[0].name.split(".")