Question

The Andriod app I’m developing is using Http Gets/Posts using PHP files on my website to perform transactions on a mysql database.

On the PHP side, I wrap the data up with JSON to parse on the java end of the app when receiving a response. I recently modified one of the tables and eliminated unnecessary values from the table. When I poll using the PHP scripts from my website, it polls correctly. When I use the app, which uses the same PHP script for polling, it returns the additional values I already removed from the database.

I’ve restarted Eclipse, cleaned the project, and restarted the android VDM to refresh it; however, it continues to find those values that were removed. Any ideas as to what is going on?

Here is the php script I’m connecting to from the app:

<?php
mysql_connect("localhost", "******", "******");
mysql_select_db("bouncet2_pogoapp");

$query = "SELECT * FROM Event_Table ORDER BY Event ASC";
$sql = mysql_query($query);

while($row=mysql_fetch_assoc($sql))
$output[]=$row;

print(json_encode($output));

mysql_close();
?>

As for my code in the app using the script:

try {
        String response = CustomHttpClient.executeHttpGet("http://www.*****.com/****/****/***/GetEvents.php");
        //System.out.println(response);

        try {
            eventArray = new JSONArray(response);
            //Log.i(SelectEventActivity.class.getName(), "Number of entries " + eventArray.length());

            m_adapterForSpinner = new ArrayAdapter<String>(this, android.R.layout.simple_spinner_item);
            m_adapterForSpinner.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);

            event_Spinner.setAdapter(m_adapterForSpinner);          

            for (int i = 0; i < eventArray.length(); i++) {
                JSONObject jsonObject = eventArray.getJSONObject(i);
                m_adapterForSpinner.add(jsonObject.getString("Event"));
                //Log.i(AddJumpersActivity.class.getName(), jsonObject.getString("Event"));
            }

        } catch (Exception e) {
            e.printStackTrace();
        }           
    } catch (Exception e) {
        e.printStackTrace();
    }

The function executeHttpGet(URL) is part of a class CustomHttpClient and is as follows:

public static String executeHttpGet(String url) throws Exception {

    StringBuilder builder = new StringBuilder();
    HttpClient client = getHttpClient();
    HttpGet request = new HttpGet();
    request.setURI(new URI(url));

    try {            
        HttpResponse response = client.execute(request);
        StatusLine statusLine = response.getStatusLine();
        int statusCode = statusLine.getStatusCode();

        if (statusCode == 200) {
            Log.i(CustomHttpClient.class.toString(), "System Status OK");
            HttpEntity entity = response.getEntity();
            InputStream content = entity.getContent();
            BufferedReader reader = new BufferedReader(new InputStreamReader(content));
            String line;
            while ((line = reader.readLine()) != null) {
                builder.append(line);
            }
        } else {
            Log.e(CustomHttpClient.class.toString(), "Failed to download file");
        } 
    } catch (ClientProtocolException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    }

    return builder.toString();            
}

Answer 1

It looks like your response is getting cached somewhere, ether in a cache server between your phone and your server, or in the phone itself.

If the cache is happening outside the phone, adding the appropriate headers to disable caching would do the trick. This would be added to the headers of the response by the server. There are several ways to do this, but I think this should work…

header("Expires: Tue, 03 Jul 2001 06:00:00 GMT");

On the phone side, depending on the HTTP Client you get from getHttpClient, it could be a client which has caching turned on. In Ice Cream Sandwich, Google added caching to the HttpURLConnection HTTP Client. Caching has to be turned on according to the docs, but many people seem to have issues with the cache being on when they where unaware. I’m not to familiar with the interworkings of the various HTTP Clients on Android, but this should be a good start…

http://developer.android.com/reference/java/net/HttpURLConnection.html

A quick and dirty check to see if something is caching the response would be to add a random, unused param to your URL when calling the server, something like…

url += "?unused=" + UUID.randomUUID();

With this in place, you should not get cached anywhere, then you can at least determine if it is a caching issue or something else, and go from there.