CODEWITHSUNDEEP
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Jar Yit
Jar Yit

Reputation: 985

How can check real file type in java?

I will create a sample.txt file. And then I will change extension of sample.txt to sample.tar

How do I know the real type of the sample file?

Upvotes: 4

Views: 5365

Answers (4)

Sebastian Annies
Sebastian Annies

Reputation: 2468

If you just want to know if a file is a tar file you can read the bytes 257, 258, 259, 260, 261. If they are ASCII 'ustar' it is a tar archive.

Upvotes: 0

Achintya Jha
Achintya Jha

Reputation: 12843

import java.net.FileNameMap;
import java.net.URLConnection;

public class FileUtils {

public static String getMimeType(String fileUrl) throws java.io.IOException {
    FileNameMap fileNameMap = URLConnection.getFileNameMap();
    String type = fileNameMap.getContentTypeFor(fileUrl);

    return type;
}

public static void main(String args[]) throws Exception {
    System.out.println(FileUtils.getMimeType("fileName.extension"));
     //for a.txt
    // output : text/plain
}
}

This works fine if the file is not rar or compressed.

Refer to this link. Get the Mime Type from a File.

Upvotes: 0

Peter Lawrey
Peter Lawrey

Reputation: 533510

A file only contains bytes. What you believe those bytes mean is entirely up to you. Any notion that a file has a real type is an illusion. For example you could have called it sample.txt but it was actually a TAR file.

There are tools to guess what the file format might be. However this is just a guess. A file doesn't have a "real" file type.

Upvotes: 5

Óscar López
Óscar López

Reputation: 236004

You can use a library such as Java Mime Magic to check if the supposed MIME type of the file matches its contents.

Upvotes: 2

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