title: Android WebView cache doesn't expire
body: <p>in my Android App I use a WebView and got a problem with caching.
  After a file is cached the WebView just keeps it forever (or at least until I delete the cache manually).</p>
  
  <p>In the Apache Access-Log I see that the WebView doesn't send requests once the file is cached. How can I setup the WebView to send requests for checking if the file is expired by using common ETags and HTTP-Code 304? On a desktop browser(Firefox, Chrome) the caching works as expected.</p>
  
  <p>Here is my code:</p>
  
  <pre><code>    webView = (WebView) findViewById(R.id.webView);
      webView.getSettings().setJavaScriptEnabled(true);
      webView.getSettings().setDomStorageEnabled(true);
      webView.setWebViewClient(new EWebViewClient(this));
      webView.getSettings().setBuiltInZoomControls(false);
      webView.getSettings().setSupportZoom(true);
      webView.getSettings().setCacheMode(WebSettings.LOAD_DEFAULT);
      webView.setWebChromeClient(new EWebChromeClient(this));
      webView.setBackgroundColor(Color.argb(1,0,0,0));
      webView.setLayerType(View.LAYER_TYPE_SOFTWARE, null);
      webView.loadUrl(url);
  </code></pre>
  
  <p>EWebViewClient only overwrites: "shouldOverrideUrlLoading, onPageFinished, onLoadResource, onReceivedError"</p>
  
  <p>I really appreciate any help you can provide.</p>