Android HttpURLConnection setRequestMethod PUT

Question

I'm trying to connect an Android app to a restful server with HttpURLConnection. The GET requests are successful but the PUT requests aren't. Every PUT request arrives at the server as a GET request.

@Override
protected Boolean doInBackground(Method... params) {
    Boolean result = false;
    try {
        URL url = new URL("http://server.com/api");
       HttpURLConnection connection = (HttpURLConnection) url.openConnection();

        switch (params[0]) {
            case PUT:
                connection.setDoOutput(true);
                connection.setRequestMethod("PUT");
                Log.d(TAG, "Method: " + connection.getRequestMethod()); // Correctly "Method: PUT"
                OutputStreamWriter out = new OutputStreamWriter(
                    connection.getOutputStream());
                out.write("Message");
                out.close();
                break;
            case GET:
                connection.setRequestMethod("GET");
                connection.connect();
                break;
            default:
                connection.setRequestMethod("GET");
                connection.connect();
                break;
        }

        if (connection.getResponseCode() == HttpURLConnection.HTTP_OK) {
            InputStream in = connection.getInputStream();

            JsonReader reader = new JsonReader(new InputStreamReader(in, "UTF-8"));

            reader.beginObject();
            while (reader.hasNext()) {
                String name = reader.nextName();
                if (name.equals("state")) {
                    result = true;
                    if (reader.nextInt() == 1) {
                        state = true;
                        Log.d(TAG, "state: 1");
                    } else {
                        state = false;
                        Log.d(TAG, "state: -1");
                    }
                } else if (name.equals("method")) {
                    method = reader.nextString(); // Server respone is "Method: GET"
                }
            }
            reader.endObject();
            in.close();
        } else {
            Log.d(TAG, "Connection failed");
        }
        connection.disconnect();
    } catch (Exception e) {
        Log.e("Exception", e.toString());
        e.printStackTrace();
    }
    return result;
}

The request method is correctly set to PUT before connection.connect();. What am I missing? I don't want to send data. The PUT request changes a counter, so no data is necessary.

Same function is implemented in Javascript with JQuery for a webfrontend and works

$.ajax({
    url: '/api',
    method: 'PUT'
});

EDIT: Maybe it's a problem with the server. Currently I'm using an php file

<?php
    echo(var_dump($_SERVER)); // ["REQUEST_METHOD"]=> string(3) "GET"
    function get ($db) {
        $state = $db->querySingle('SELECT state FROM states WHERE name="main"');
        echo('{"state": ' . $state . ', "method": "get"}');
    }
    function put ($db) {
        $state = $db->querySingle('SELECT state FROM states WHERE name="main"');
        $db->exec('UPDATE states SET state=' . ($state+1)%2 . ' WHERE name="main"');
        $state = $db->querySingle('SELECT state FROM states WHERE name="main"');
        echo('{"state": ' . $state . ', "method": "put"}');
}

    if ($db = new SQLite3('database.sqlite')) {
        switch($_SERVER['REQUEST_METHOD']){
            case 'GET':
                get($db);
                break;
            case 'PUT':
                put($db);
                break;
        }
        $db->close();
    } else {
    }
?>

I tried my app with http://httpbin.org/put and it worked.

Answer 1

I found the problem. I have to append a trailing slash to the url otherwise the request is redirected and transformed to a GET request. I don't exactly understand the problem but I found a solution for me.

I have to change

URL url = new URL("http://server.com/api");

to

URL url = new URL("http://server.com/api/");

And now it works. Maybe someone can explain it to me. When I try to open http://server.com/api with curl I get a 303 redirect to http://server.com/api.