Apache Tika and Json

Question

When I use Apache Tika to determine the file type from the content. XML file is fine but not the json. If content type is json, it will return "text/plain" instead of "application/json".

Any help?

public static String tiKaDetectMimeType(final File file) throws IOException {
    TikaInputStream tikaIS = null;
    try {
        tikaIS = TikaInputStream.get(file);
        final Metadata metadata = new Metadata();
        return DETECTOR.detect(tikaIS, metadata).toString();
    } finally {
        if (tikaIS != null) {
            tikaIS.close();
        }
    }
}

Answer 1

JSON is based on plain text, so it's not altogether surprising that Tika reported it as such when given only the bytes to work with.

Your problem is that you didn't also supply the filename, so Tika didn't have that to work with. If you had, Tika could've said bytes=plain text + filename=json => json and given you the answer you expected

The line you're missing is:

metadata.set(Metadata.RESOURCE_NAME_KEY, filename);

So the fixed code snippet would be:

tikaIS = TikaInputStream.get(file);
final Metadata metadata = new Metadata();
metadata.set(Metadata.RESOURCE_NAME_KEY, file.getName());
return DETECTOR.detect(tikaIS, metadata).toString();

With that, you'll get back an answer of JSON as you were expecting

Answer 2

For those not dealing with a file I've found it easiest to just run the payload through Jackson to see if it can be parsed or not. If Jackson can parse it you know 1) you are working with JSON and 2) the JSON is valid.

private static final ObjectMapper MAPPER = new ObjectMapper();
public static boolean isValidJSON(final String json) {
    boolean valid = true;
    try {
        MAPPER.readTree(json);
    } catch (IOException e) {
        valid = false;
    }
    return valid;
}