Unable to start a WebView from an AsyncTask

问题

I'd like to start a WebView from my AsyncTask but it doesn't seem to run. This is what my onPostExecute method looks like:

  public class Viewer extends AsyncTask<URI, Integer, URI> {

      private Activity objContext = null;

      public Viewer(Activity objContext) {
        this.objContext = objContext;
      }

      protected void onPostExecute(URI uriWebpage) {
          WebView wbvBrowser = new WebView(this.objContext);
          wbvBrowser.getSettings().setBuiltInZoomControls(true);
          wbvBrowser.getSettings().setJavaScriptEnabled(true);
          wbvBrowser.loadUrl(uriWebpage.toString());
      }

  }

My task is used by two activities in my application and therefore my global objContext variable is of type Activity. If I change the type of my objContext variable to the name of the calling class, it works fine but then I can't instantiate my task from the other calling class. I instantiate my task like this.

Viewer mytask = new Viewer(this);

How can I solve this?

回答1:

Did you setContentView from original layout to webView or you have a container to put webview? otherwise I don't think webView UI appears.

回答2:

Are you sure you execute your AsyncTask

                    @Override
            protected void onPostExecute(Void result){              


            }
        }.execute();

Also need to class name

Viewer mytask = new Viewer(YourclassName.this);

// or This may Helps you

     private Context  mcontext;

          public Viewer(Context  objContext) {
            this.mcontext= objContext;
          }

  protected void onPostExecute(URI uriWebpage) {
          WebView wbvBrowser = new WebView(((Activity)(mcontext)));

      }

回答3:

I have solved the issue. It has nothing to do with the use of Activity or Context. Both work just fine. Some URLs don't seem to load the WebView. I changed the URL of the WebView to point to a site like Google and it worked just fine. Seems like if the URL is incorrect, the WebView doesn't throw an exception but doesn't open up either.

回答4:

I don't know why this happens, but why don't you just start the built in web browser through an Intent in your onPostExecute(Uri uriWebpage)?

Intent intent = new Intent(Intent.ACTION_VIEW);
intent.setData(uriWebPage);
startActivity(intent);

If this solution doesn't satisfy you, then please post the error stack trace from LogCat.

来源：https://stackoverflow.com/questions/12302194/unable-to-start-a-webview-from-an-asynctask