Reputation: 3956
Issues with Volley caching mechanism
I have a website which publishes news on daily basis.
Now, I'm sending a JsonArrayRequest to retrieve and parse the title and summary of each news published on the website. The parsed items are then used to populate RecyclerView.
The problem I'm having is the way volley implements caching .
Let's take this scenario: the app is installed, launched and the RecyclerView is populated. The user reads the news and forgets about the app
Later, the user launches the app and the items are fetched and RecyclerView is populated.
Between the first and the second launch, new news are published on the website. But in the second launch, these new items are not displayed. However, if the user manually go to app settings and clear cache of the app, and relaunch, the new items are displayed.
You get my point?
While I don't want to disable Volley caching, how do I make it to always fetch new items?
EDIT
MainActivity
public class MainActivity extends AppCompatActivity {
private final String TAG = "MainActivity";
//Creating a list of newss
private List<NewsItems> mNewsItemsList;
//Creating Views
private RecyclerView recyclerView;
private RecyclerView.Adapter adapter;
private RecyclerView.LayoutManager layoutManager;
private ProgressDialog mProgressDialog;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Log.d(TAG, "onCreate called");
//Initializing Views
recyclerView = (RecyclerView) findViewById(R.id.news_recycler);
LinearLayoutManager layoutManager = new LinearLayoutManager(this);
recyclerView.setLayoutManager(layoutManager);
//Initializing the newslist
mNewsItemsList = new ArrayList<>();
adapter = new NewsAdapter(mNewsItemsList, this);
recyclerView.setAdapter(adapter);
if (NetworkCheck.isAvailableAndConnected(this)) {
//Calling method to get data
getData();
} else {
//Codes for building Alert Dialog
alertDialogBuilder.setPositiveButton(R.string.alert_retry, new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
if (!NetworkCheck.isAvailableAndConnected(mContext)) {
alertDialogBuilder.show();
} else {
getData();
}
}
});
alertDialogBuilder.setNegativeButton(R.string.alert_cancel, new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
finish();
}
});
alertDialogBuilder.show();
}
}
//This method will get data from the web api
private void getData(){
Log.d(TAG, "getData called");
//Codes for Showing progress dialog
//Creating a json request
JsonArrayRequest jsonArrayRequest = new JsonArrayRequest(ConfigNews.GET_URL + getNumber(),
new Response.Listener<JSONArray>() {
@Override
public void onResponse(JSONArray response) {
Log.d(TAG, "onResponse called");
//Dismissing the progress dialog
if (mProgressDialog != null) {
mProgressDialog.hide();
}
//calling method to parse json array
parseData(response);
}
},
new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError error) {
}
});
//Creating request queue
RequestQueue requestQueue = Volley.newRequestQueue(this);
//Adding request to the queue
requestQueue.add(jsonArrayRequest);
}
//This method will parse json data
private void parseData(JSONArray array){
Log.d(TAG, "Parsing array");
for(int i = 0; i<array.length(); i++) {
NewsItems newsItem = new NewsItems();
JSONObject jsonObject = null;
try {
jsonObject = array.getJSONObject(i);
newsItem.setNews_title(jsonObject.getString(ConfigNews.TAG_VIDEO_TITLE));
newsItem.setNews_body(jsonObject.getString(ConfigNews.TAG_VIDEO_BODY));
} catch (JSONException w) {
w.printStackTrace();
}
mNewsItemsList.add(newsItem);
}
adapter.notifyItemRangeChanged(0, adapter.getItemCount());
}
@Override
public void onDestroy() {
super.onDestroy();
Log.d(TAG, "onDestroy called");
if (mProgressDialog != null){
mProgressDialog.dismiss();
Log.d(TAG, "mProgress dialog dismissed");
}
}
}
Upvotes: 0
Views: 1376
Answers (1)
Reputation: 3576
Option 1) Delete Cache
before you make a call you can delete the whole cache by myDiskBasedCache.clear() or specific entries by myDiskBasedCache.remove(entryUrl)
Option 2) Custom CacheParser (in the Request)
@Override
protected Response<Bitmap> parseNetworkResponse(NetworkResponse response) {
Response<Bitmap> resp = super.parseNetworkResponse(response);
if(!resp.isSuccess()) {
return resp;
}
long now = System.currentTimeMillis();
Cache.Entry entry = resp.cacheEntry;
if(entry == null) {
entry = new Cache.Entry();
entry.data = response.data;
entry.responseHeaders = response.headers;
entry.ttl = now + 60 * 60 * 1000; //keeps cache for 1 hr
}
entry.softTtl = 0; // will always refresh
return Response.success(resp.result, entry);
}
Option 3) send requests that does not cache
myRequest.setShouldCache(false);
Option 4) use custom Cache implementation
UPDATE:
Example with your code:
//Creating a json request
JsonArrayRequest jsonArrayRequest = new JsonArrayRequest(ConfigNews.GET_URL + getNumber(),
new Response.Listener<JSONArray>() {
@Override
public void onResponse(JSONArray response) {
Log.d(TAG, "onResponse called");
//Dismissing the progress dialog
if (mProgressDialog != null) {
mProgressDialog.hide();
}
//calling method to parse json array
parseData(response);
}
},
new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError error) {
}
}) {
@Override
protected Response<JSONArray> parseNetworkResponse(NetworkResponse response) {
Response<JSONArray> resp = super.parseNetworkResponse(response);
if(!resp.isSuccess()) {
return resp;
}
long now = System.currentTimeMillis();
Cache.Entry entry = resp.cacheEntry;
if(entry == null) {
entry = new Cache.Entry();
entry.data = response.data;
entry.responseHeaders = response.headers;
entry.ttl = now + 60 * 60 * 1000; //keeps cache for 1 hr
}
entry.softTtl = 0; // will always refresh
return Response.success(resp.result, entry);
}
};
UPDATE 2
Http protocol caching supports many ways to define how the client can cache responses and when to update them. Volley simplifies those rules to:
- entry.ttl (time to live in ms) if greater than the current time then cache can be used otherwise fresh request needs to be made
and
entry.softTtl (soft time to live in ms :) if greater than the current time cache is absolutely valid and no request to the server needs to be made, otherwise new request is still made (even if the ttl is good) and if there is a change new response will be delivered.
note that if ttl is valid and softTtl is not you can receive 2 onResponse calls
Upvotes: 1