Android volley - Override Cache Timeout for JSON request

Question

I'm trying to cache JSON requests from a server, however, they are incorrectly using the Cache-Control header, amongst others (everything expires in the past). I want to override it so that calls are cached for say, 3 hours, regardless of what the server requests. Is that possible? The documentation for Volley is Scarce.

Answer 1

You might subclass the JsonObjectRequest class and overwrite parseNetworkResponse. You will notice the call to HttpHeaderParser.parseCacheHeaders - it's a good place to start :] just wrap this call or replace it and provide your own dummy Cache header configuration object [with your proprietary clientside cache time] to Response.success.

In my implementation it looks like this:

parseNetworkResponse

return Response.success(payload, enforceClientCaching(HttpHeaderParser.parseCacheHeaders(response), response));

with enforceClientCaching related members being

protected static final int defaultClientCacheExpiry = 1000 * 60 * 60; // milliseconds; = 1 hour

protected Cache.Entry enforceClientCaching(Cache.Entry entry, NetworkResponse response) {
    if (getClientCacheExpiry() == null) return entry;

    long now = System.currentTimeMillis();

    if (entry == null) {
        entry = new Cache.Entry();
        entry.data = response.data;
        entry.etag = response.headers.get("ETag");
        entry.softTtl = now + getClientCacheExpiry();
        entry.ttl = entry.softTtl;
        entry.serverDate = now;
        entry.responseHeaders = response.headers;
    } else if (entry.isExpired()) {
        entry.softTtl = now + getClientCacheExpiry();
        entry.ttl = entry.softTtl;
    }

    return entry;
}

protected Integer getClientCacheExpiry() {
    return defaultClientCacheExpiry;
}

It handles 2 cases:

• no Cache headers were set
• Server cache entry indicates expired item

So if the server starts sending correct cache headers with expiry in the future, it will still work.