How to refresh Volley caching

问题

I have enabled Volley caching to view data in offline mode also. JSON data is updated with certain time period. But I can't update new json data with SwipeRefreshLayout. If I removed Volley caching code, data is refreshed. I want to expire old cache and load new cache while clicking refresh button.

I have the following code to refresh.

mSwipeRefreshLayout = (SwipeRefreshLayout) findViewById(R.id.swipeRefreshLayout);
mSwipeRefreshLayout.setOnRefreshListener(new SwipeRefreshLayout.OnRefreshListener() {
    @Override
    public void onRefresh() {
        mExampleList.clear();
        parseJSON();
        mSwipeRefreshLayout.setRefreshing(true);

        if (mSwipeRefreshLayout != null && mSwipeRefreshLayout.isRefreshing()) {
            mSwipeRefreshLayout.setRefreshing(false);  // This hides the spinner
        }
    }
});
mExampleList = new ArrayList<>();

mRequestQueue = Volley.newRequestQueue(this);
parseJSON();

Here's how I implemented JSON parsing and enabling volley cache.

private void parseJSON() {

    String url = "http://fitandfineindustries.com/newsapi.php";

    JsonObjectRequest request = new JsonObjectRequest(Request.Method.GET, url, null,
            new Response.Listener<JSONObject>() {
                @Override
                public void onResponse(JSONObject response) {
                    try {
                        JSONArray jsonArray = response.getJSONArray("info");

                        for (int i = 0; i < jsonArray.length(); i++) {
                            JSONObject hit = jsonArray.getJSONObject(i);

                            String creatorName = hit.getString("heading");
                            String img = hit.getString("img");
                            String imageUrl = img.length() == 0 ? "file:///android_asset/fitandfineindustries.jpg" : "http://fitandfineindustries.com/images/plan/"+img;

                            mExampleList.add(new NewsItem(imageUrl, creatorName));
                        }

                        mNewsAdapter = new NewsAdapter(AgroActivity.this, mExampleList);
                        mRecyclerView.setAdapter(mNewsAdapter);
                        mNewsAdapter.setOnItemClickListener(AgroActivity.this);

                    } catch (JSONException e) {
                        e.printStackTrace();
                    }
                }
            }, new Response.ErrorListener() {
        @Override
        public void onErrorResponse(VolleyError error) {
            error.printStackTrace();
        }
    }){
        @Override
        protected Response<JSONObject> parseNetworkResponse(NetworkResponse response) {
            try {
                Cache.Entry cacheEntry = HttpHeaderParser.parseCacheHeaders(response);
                if (cacheEntry == null) {
                    cacheEntry = new Cache.Entry();
                }
                final long cacheHitButRefreshed = 1 * 60 * 1000; // in 1 minutes cache will be hit, but also refreshed on background
                final long cacheExpired = 24 * 60 * 60 * 1000; // in 24 hours this cache entry expires completely
                long now = System.currentTimeMillis();
                final long softExpire = now + cacheHitButRefreshed;
                final long ttl = now + cacheExpired;
                cacheEntry.data = response.data;
                cacheEntry.softTtl = softExpire;
                cacheEntry.ttl = ttl;
                String headerValue;
                headerValue = response.headers.get("Date");

                if (headerValue != null) {
                    cacheEntry.serverDate = HttpHeaderParser.parseDateAsEpoch(headerValue);
                }

                headerValue = response.headers.get("Last-Modified");

                if (headerValue != null) {
                    cacheEntry.lastModified = HttpHeaderParser.parseDateAsEpoch(headerValue);
                }

                cacheEntry.responseHeaders = response.headers;
                final String jsonString = new String(response.data,
                        HttpHeaderParser.parseCharset(response.headers));
                return Response.success(new JSONObject(jsonString), cacheEntry);
            } catch (UnsupportedEncodingException e) {
                return Response.error(new ParseError(e));
            } catch (JSONException e) {
                return Response.error(new ParseError(e));
            }
        }

        @Override
        protected void deliverResponse(JSONObject response) {
            super.deliverResponse(response);
        }

        @Override
        public void deliverError(VolleyError error) {
            super.deliverError(error);
        }

        @Override
        protected VolleyError parseNetworkError(VolleyError volleyError) {
            return super.parseNetworkError(volleyError);
        }
    };
    mRequestQueue.add(request);
}

来源：https://stackoverflow.com/questions/49584210/how-to-refresh-volley-caching