Access the http response headers in a WebView?

Question

Is there a way to view the http response headers in an Activity once a web page has been loaded in a WebView? Seems like this should be possible, but I can't find any methods that expose the headers.

Answer 1

Neither WebView nor WebViewClient provide methods to do that, Though, you can try to implement that manually. You can do something like this:

private WebView webview; public void onCreate(Bundle icicle){     // bla bla bla      // here you initialize your webview     webview = new WebView(this);     webview.setWebViewClient(new YourWebClient()); }  // this will be the webclient that will manage the webview private class YourWebClient extends WebViewClient{      // you want to catch when an URL is going to be loaded     public boolean  shouldOverrideUrlLoading  (WebView  view, String  urlConection){         // here you will use the url to access the headers.         // in this case, the Content-Length one         URL url;         URLConnection conexion;         try {             url = new URL(urlConection);             conexion = url.openConnection();             conexion.setConnectTimeout(3000);             conexion.connect();             // get the size of the file which is in the header of the request             int size = conexion.getContentLength();         }           // and here, if you want, you can load the page normally         String htmlContent = "";         HttpGet httpGet = new HttpGet(urlConection);         // this receives the response         HttpResponse response;         try {             response = httpClient.execute(httpGet);             if (response.getStatusLine().getStatusCode() == 200) {                 // la conexion fue establecida, obtener el contenido                 HttpEntity entity = response.getEntity();                 if (entity != null) {                     InputStream inputStream = entity.getContent();                     htmlContent = convertToString(inputStream);                 }             }          } catch (Exception e) {}           webview.loadData(htmlContent, "text/html", "utf-8");          return true;     }      public String convertToString(InputStream inputStream){         StringBuffer string = new StringBuffer();         BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream));         String line;         try {             while ((line = reader.readLine()) != null) {                 string.append(linea + "\n");             }         } catch (IOException e) {}         return string.toString();     } } 

I can't test it right now, but that's basically what you could do (it's very crazy though :).

Answer 2

inspired by Cristian answer I needed to intercept AJAX calls webview is doing, where I needed to intercept response headers to get some information (cart item count in e-commerce app), which I needed to leverage in app. As the app is using okhttp I've ended up doing this and it's working:

        @TargetApi(Build.VERSION_CODES.LOLLIPOP)         @Override         public WebResourceResponse shouldInterceptRequest(WebView view, WebResourceRequest request) {             Log.i(TAG,"shouldInterceptRequest path:"+request.getUrl().getPath());             WebResourceResponse returnResponse = null;             if (request.getUrl().getPath().startsWith("/cart")) { // only interested in /cart requests                 returnResponse = super.shouldInterceptRequest(view, request);                 Log.i(TAG,"cart AJAX call - doing okRequest");                 Request okRequest = new Request.Builder()                         .url(request.getUrl().toString())                         .post(null)                         .build();                 try {                     Response okResponse = app.getOkHttpClient().newCall(okRequest).execute();                     if (okResponse!=null) {                         int statusCode = okResponse.code();                         String encoding = "UTF-8";                         String mimeType = "application/json";                         String reasonPhrase = "OK";                         Map<String,String> responseHeaders = new HashMap<String,String>();                         if (okResponse.headers()!=null) {                             if (okResponse.headers().size()>0) {                                 for (int i = 0; i < okResponse.headers().size(); i++) {                                     String key = okResponse.headers().name(i);                                     String value = okResponse.headers().value(i);                                     responseHeaders.put(key, value);                                     if (key.toLowerCase().contains("x-cart-itemcount")) {                                         Log.i(TAG,"setting cart item count");                                         app.setCartItemsCount(Integer.parseInt(value));                                     }                                 }                             }                         }                         InputStream data = new ByteArrayInputStream(okResponse.body().string().getBytes(StandardCharsets.UTF_8));                         Log.i(TAG, "okResponse code:" + okResponse.code());                         returnResponse = new WebResourceResponse(mimeType,encoding,statusCode,reasonPhrase,responseHeaders,data);                     } else {                         Log.w(TAG,"okResponse fail");                     }                 } catch (IOException e) {                     e.printStackTrace();                 }             }             return returnResponse;         } 

I hope this may be helpful to others and if somebody has a suggestions for improvement I would be grateful. Unfortunately it's compatible only with LOLLIPOP and higher as from this version you can access/return headers using WebResourceRequest, which was needed for my case.