How to use Cache offline, else use network

Question

I am trying to create a application that shows a WebView. I want it to display the cached version when there is no network. Else if there is a network available, it should load the WebView from the URL.

So far so good, except that it uses cached version all the time, even when there is network available. So I would like to ask if there is anything wrong with the code below. It seems that I am missing something.

I have tried both with the code below, and without it. I've found the following: no matter what I try, it seems that the app is always using the "cached" version. At this point i'm not even sure that it's truly using the cache, since I can only get it to load the website from URL again, when I have cleared App Data (not the cache).

Android version 6.0.1 API level 23

mWebView.getSettings().setAppCachePath(getApplicationContext().getCacheDir().getAbsolutePath() );
mWebView.getSettings().setAllowFileAccess( true );
mWebView.getSettings().setAppCacheEnabled( true );
mWebView.getSettings().setJavaScriptEnabled( true );
mWebView.getSettings().setCacheMode( WebSettings.LOAD_DEFAULT );

if ( !isNetworkAvailable() ) { // loading offline
mWebView.getSettings().setCacheMode(WebSettings.LOAD_CACHE_ELSE_NETWORK);
}

mWebView.loadUrl("https://path.to.my/website/index.html");

Expected result: When phone has network, I expect it to fetch the website from the URL.

Actual result: When the installation is fresh, the website has been fetched from the url. Then after that, it will only use the cached version. (Or perhaps the verion stored in App Data. Not sure how that works.)

UPDATE:

I got it working, and it's now looking like this: (Unsure if this is the "best-practice" way to do it, though)

WebSettings webSettings = mWebView.getSettings();

        webSettings.setAppCacheEnabled(true);
        webSettings.setAllowFileAccess( true );
        webSettings.setAppCachePath(getBaseContext().getCacheDir().getPath());
        //webSettings.setJavaScriptEnabled( true );

        if ( !isNetworkAvailable() ) { // loading offline
            webSettings.setCacheMode( WebSettings.LOAD_CACHE_ONLY );
            Toast.makeText(mContext, "DEBUG: No net",Toast.LENGTH_SHORT).show();
        }

        mWebView.loadUrl("https://path.to.my/website/index.html");

score 0 · Answer 1 · edited Jun 20 '20 at 09:12

0

The problem is with LOAD_DEFAULT. From official documentation:

LOAD_DEFAULT

Default cache usage mode. If the navigation type doesn't impose any specific behavior, use cached resources when they are available and not expired, otherwise load resources from the network.

It'll load from cache when you want it to load from network.

Try this when there is network:

mWebView.getSettings().setCacheMode(WebSettings.LOAD_NO_CACHE);

And when there isn't network, use:

mWebView.getSettings().setCacheMode(WebSettings.LOAD_CACHE_ONLY);

See this answer for more info.

edited Jun 20 '20 at 09:12

Community

1
1

answered Apr 22 '19 at 10:37

ronginat

1,910
1
12
23

Thank you for trying to help! This did not solve it, however. Only manually clearing the apps data will get it to load from URL. I have tried using both Wi-fi and the regular mobile network. (In case the isNetworkAvailable() didn't trigger on Wi-fi, only mobile). Still no luck. – Web Apr 22 '19 at 11:16
Maybe not calling `setAppCacheEnabled(true)` and `setAppCachePath(path)` will help – ronginat Apr 22 '19 at 12:27
Thank you for the advice. Did not work, sadly. I have gotten it to work by removing ```setJavaScriptEnabled(true)``` and also removing ```webSettings.setCacheMode( WebSettings.LOAD_NO_CACHE);``` I have updated my original post. – Web Apr 22 '19 at 18:45

score 0 · Answer 2 · edited Apr 22 '19 at 11:47

0

   if (!isNetworkAvailable()) { // loading offline
        mWebView.getSettings().setCacheMode(WebSettings.LOAD_CACHE_ELSE_NETWORK);
   } else {
     mWebView.getSettings().setCacheMode(WebSettings.LOAD_DEFAULT);
   }

edited Apr 22 '19 at 11:47

Iwo Kucharski

3,735
3
50
66

answered Apr 22 '19 at 10:41

Darshan

4,020
2
18
49

How to use Cache offline, else use network

2 Answers2