Loading Cache when Offline in Android Webview

问题

I have an application which loads urls from a website. Now I want that the application to use the cache when offline. But I just get the failure page which says that im not connected to the website. At first I set the Cachemode to Load_Normal but this doesn't help. Next I tried a realy "silly" approach using the ConnectivityManager:

cm = (ConnectivityManager) this.getSystemService(Activity.CONNECTIVITY_SERVICE);
if(cm.getActiveNetworkInfo().isConnected()){
  mfnWebView.getSettings().setCacheMode(WebSettings.LOAD_DEFAULT);
  mfnWebView.loadUrl(url);
}
else{
  mfnWebView.getSettings().setCacheMode(WebSettings.LOAD_CACHE_ELSE_NETWORK);
  mfnWebView.loadUrl(url);
}

but this just leads to crashing the application.

Is there a simple way to load the cache when offline and existing and just if not existing showing the failure message.

回答1:

OK. The code is fine above. The permission needed to be added are:

.INTERNET

.ACCESS_NETWORK_STATE

.ACCESS_WIFI_STATE

回答2:

In addition to the permissions

.INTERNET

.ACCESS_NETWORK_STATE

.ACCESS_WIFI_STATE

mentioned in another answer, I also needed the following changes to the code:

if(cm != null && cm.getActiveNetworkInfo() != null && cm.getActiveNetworkInfo().isConnected()){
    webView.getSettings().setCacheMode(WebSettings.LOAD_DEFAULT);
}
else{
    webView.getSettings().setCacheMode(WebSettings.LOAD_CACHE_ELSE_NETWORK);
}

Otherwise the app would crash when trying to get the network info on first startup, if I were not connected to either WiFi or Mobile Network.

来源：https://stackoverflow.com/questions/3787800/loading-cache-when-offline-in-android-webview

标签

android

caching

webview

offline