WebView - 没有连接和内容片段

Question

我想在应用程序连接到互联网时显示正常的 webview（实际上这就是我所拥有的并想要添加第二个片段），但是当它没有连接到互联网时（它可以工作，但它显示网页不可用，默认android 浏览器，我不想要它），我想显示另一个带有文本视图和按钮 TRY AGAIN 的片段。有人可以帮助我吗？我正在使用 SherlockFragment，在下面我使用 Webview 发布代码，而没有另一个片段。感谢您的任何回答。

    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {
        View v = inflater.inflate(R.layout.layout, container, false);
        if (isOnline()){
        WebView myWebView = (WebView) v.findViewById(R.id.id);

        final ProgressDialog progressDialog;
        progressDialog = new ProgressDialog(getActivity());
        progressDialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);
        progressDialog.setMessage("Prosím čakajte. Prebieha načítavanie...");
        progressDialog.setCancelable(true);
        progressDialog.setProgress(0);
        progressDialog.show();

        myWebView.setWebChromeClient(new WebChromeClient() {
            public void onProgressChanged(WebView view, int progress) {
                  if(progressDialog != null)
                      progressDialog.setProgress(0);
                      getActivity().setProgress(progress * 1000);
                      progressDialog.incrementProgressBy(progress);
                      if (progress == 100 && progressDialog.isShowing())
                          progressDialog.dismiss();
                  }

      });

        myWebView.getSettings().setBuiltInZoomControls(false); 
        myWebView.getSettings().setSupportZoom(false);
        myWebView.getSettings().setJavaScriptCanOpenWindowsAutomatically(true);   
        myWebView.getSettings().setAllowFileAccess(true); 
        myWebView.getSettings().setDomStorageEnabled(true);
        myWebView.getSettings().setJavaScriptEnabled(true);

        myWebView.loadUrl("webpage");        
    }
        else{
            Intent intent = new Intent(getActivity(), class.class);
            getActivity().startActivity(intent);
        }
        return v;
    }
    private boolean isOnline() {

        ConnectivityManager conMgr = (ConnectivityManager) context.getSystemService (Context.CONNECTIVITY_SERVICE);
        if (conMgr.getActiveNetworkInfo() != null
        && conMgr.getActiveNetworkInfo().isAvailable()
        && conMgr.getActiveNetworkInfo().isConnected()) {
        return true;

        } else {
        Log.v(getTag(), "Internet Connection Not Present");
        return false;
        }
    }
  }

记录猫

12-08 09:17:57.852: E/AndroidRuntime(17630): FATAL EXCEPTION: main
12-08 09:17:57.852: E/AndroidRuntime(17630): java.lang.NullPointerException
12-08 09:17:57.852: E/AndroidRuntime(17630):    at sk.soszm.polytechnicka.Novinky.isOnline(Novinky.java:71)
12-08 09:17:57.852: E/AndroidRuntime(17630):    at sk.soszm.polytechnicka.Novinky.onCreateView(Novinky.java:31)
12-08 09:17:57.852: E/AndroidRuntime(17630):    at android.support.v4.app.Fragment.performCreateView(Fragment.java:1478)
12-08 09:17:57.852: E/AndroidRuntime(17630):    at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:927)
12-08 09:17:57.852: E/AndroidRuntime(17630):    at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1104)
12-08 09:17:57.852: E/AndroidRuntime(17630):    at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:682)
12-08 09:17:57.852: E/AndroidRuntime(17630):    at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1460)
12-08 09:17:57.852: E/AndroidRuntime(17630):    at android.support.v4.app.FragmentManagerImpl$1.run(FragmentManager.java:440)
12-08 09:17:57.852: E/AndroidRuntime(17630):    at android.os.Handler.handleCallback(Handler.java:725)
12-08 09:17:57.852: E/AndroidRuntime(17630):    at android.os.Handler.dispatchMessage(Handler.java:92)
12-08 09:17:57.852: E/AndroidRuntime(17630):    at android.os.Looper.loop(Looper.java:137)
12-08 09:17:57.852: E/AndroidRuntime(17630):    at android.app.ActivityThread.main(ActivityThread.java:5039)
12-08 09:17:57.852: E/AndroidRuntime(17630):    at java.lang.reflect.Method.invokeNative(Native Method)
12-08 09:17:57.852: E/AndroidRuntime(17630):    at java.lang.reflect.Method.invoke(Method.java:511)
12-08 09:17:57.852: E/AndroidRuntime(17630):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
12-08 09:17:57.852: E/AndroidRuntime(17630):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
12-08 09:17:57.852: E/AndroidRuntime(17630):    at dalvik.system.NativeStart.main(Native Method)

Answer 1

您可以监控设备是否连接到互联网。如果未连接，只需将WebView 的可见性设置为GONE 并显示一条短信。

使用它来检查互联网连接：

ConnectivityManager cm =
        (ConnectivityManager)context.getSystemService(Context.CONNECTIVITY_SERVICE);

NetworkInfo activeNetwork = cm.getActiveNetworkInfo();
boolean isConnected = activeNetwork != null &&
                      activeNetwork.isConnectedOrConnecting();

来源：http://developer.android.com/training/monitoring-device-state/connectivity-monitoring.html

获得连接状态后，请执行以下操作：

if(isConnected) {
  //your WebView code
} else {
  //TextView showing "Try Again"
}

您可以使用setVisibility(int) 以编程方式显示/隐藏视图

来源：http://developer.android.com/reference/android/view/View.html#setVisibility%28int%29