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Getting A File"s Mime Type In Java



I was just wondering how most people fetch a mime type from a file in Java? So far I've tried two utils: JMimeMagic & Mime-Util. The first gave me memory exceptions, the second doesn't close its streams off properly. I was just wondering if anyone else had a method/library that they used and worked correctly?




Comments

  1. Getting A File’s Mime Type In Java

    ReplyDelete
  2. Unfortunately,

    mimeType = file.toURL().openConnection().getContentType();


    does not work, since this use of URL leaves a file locked, so that, for example, it is undeletable.

    However, you have this:

    mimeType= URLConnection.guessContentTypeFromName(file.getName());


    and also the following, which has the advantage of going beyond mere use of file extension, and takes a peek at content

    InputStream is = new BufferedInputStream(new FileInputStream(file));
    mimeType = URLConnection.guessContentTypeFromStream(is);
    //...close stream


    However, as suggested by the comment above, the built-in table of mime-types is quite limited, not including, for example, MSWord and PDF. So, if you want to generalize, you'll need to go beyond the built-in libraries, using, e.g., Mime-Util (which is a great library, using both file extension and content).

    ReplyDelete
  3. The JAF API is part of JDK 6. Look at javax.activation package.

    Most interesting classes are javax.activation.MimeType - an actual MIME type holder - and javax.activation.MimetypesFileTypeMap - class whose instance can resolve MIME type as String for a file:

    String fileName = "/path/to/file";
    MimetypesFileTypeMap mimeTypesMap = new MimetypesFileTypeMap();

    // only by file name
    String mimeType = mimeTypesMap.getContentType(fileName);

    // or by actual File instance
    File file = new File(fileName);
    mimeType = mimeTypesMap.getContentType(file);

    ReplyDelete
  4. From roseindia:

    FileNameMap fileNameMap = URLConnection.getFileNameMap();
    String mimeType = fileNameMap.getContentTypeFor("alert.gif");

    ReplyDelete

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