FileNotFoundException for HttpURLConnection in Ice Cream Sandwich

Question

I have an Android app that works fine with Android 2.x and 3.x, but it fails when run on Android 4.x.

The problem is in this section of code:

URL url = new URL("http://blahblah.blah/somedata.xml");
HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();
urlConnection.setRequestMethod("GET");
urlConnection.setDoOutput(true);
urlConnection.connect();

InputStream inputStream = urlConnection.getInputStream();

When the application is running on Android 4.x, the getInputStream() call results in a FileNotFoundException. When the same binary is running on earlier versions of Android, it succeeds. The URLs also work fine in web browsers and with curl.

Apparently something about HttpURLConnection has changed in ICS. Does anybody have any idea what has changed, and/or what the fix might be?

Famine

The docs say that setDoOutput(true) implies setRequestMethod("POST"). Which do you mean? – Emanate

It's meant to do a GET. (I didn't write the code, so I don't know why setDoOutput(true) was there.) – Famine

FWIW, setRequestMethod("GET") and setDoOutput(true) appear in a lot of sample code for using HttpURLConnection. Where is it documented that it forces a POST? – Famine

HTTP Methods HttpURLConnection uses the GET method by default. It will use POST if setDoOutput(true) has been called. developer.android.com/reference/java/net/HttpURLConnection.html – Emanate

it's quite old, but what i did is just i ommited the conn.setRequestMethod("GET") , we set the conn.setDoOutput(true) which means it's a POST and vis versa – Tumescent

from docs: setDoOutput(true) :Sets the flag indicating whether this {@code URLConnection} allows output. It cannot be set after the connection is established. – Procurable

Answer 1

Try removing the setDoOutput call. Taken from this blog: a blog

Edit: This is needed when using a POST call.

Two

Yeah, sure enough, removing that line makes it work on ICS, and it seems to still work on older Android as well. – Famine

Note that this is needed, when making a POST request! In that case, it should be kept in place. – Stir

Hey guys. What do you do when you are using a POST call? – Heterogenous

Answer 2

A FileNotFoundException may also been thrown if the server returns a bad error code (e.g., 400 or 401). You can handle this as follows:

int responseCode = con.getResponseCode(); //can call this instead of con.connect()
if (responseCode >= 400 && responseCode <= 499) {
    throw new Exception("Bad authentication status: " + responseCode); //provide a more meaningful exception message
}
else {
    InputStream in = con.getInputStream();
    //etc...
}

Dagenham

I was getting response code 500, because I hadn't set Content-Type, thanks for pointing out that this exception might be thrown in those cases. – Smocking

For anyone wondering why they don't have the "getResponseCode()" method: just cast your connection to a HttpURLConnection – Letdown

Does anyone know why Android throws a FileNotFoundException on codes which clearly aren't 404? – Uplift

@DavidLord I had this error because my URL wasn't properly formatted. I used URLEncoder.encode(myURL, "UTF-8"); for the part of my URL that contained a space character, and it all went well. – Patentor

Answer 3

I Don't know why, but dealing manually with redirection resolves the problem.

connection.setInstanceFollowRedirects(false);

Rebel

In my situation, I was using an Authorization header to load a script on my website, which redirects to a pre-signed URL on Digital Ocean Spaces (S3 compatible). Android was also sending the Authorization header with the redirected request and that was causing Spaces to return a 400 error. This is on Android 5; later versions don't do this. – Olander

Answer 4

A little late but you can also verify the accepted content. You can add this line to accept all kinds of contents

urlConnection.setRequestProperty("Accept","*/*");

Comedic