I am trying to block facebook on system browser

问题

For this,first i am getting the top activity from the stack and then matching the string of Facebook in logcat.. I am using this Code,

public class MyService extends Service 
{
    public static  String Tag  = "Task";
    public static  String Tag1 = "Top Running Task";
    ActivityManager am ;
    String packageName ;
    Handler handler;
    int count=0;
      @Override
      public int onStartCommand(Intent intent,int flags, int startId) 
      {
            // TODO Auto-generated method stub
            super.onStartCommand(intent, flags,startId);
            Toast.makeText(this, "Service running", Toast.LENGTH_SHORT).show();

            handler = new Handler(){

                @Override
                public void handleMessage(Message msg) 
                {
                    // TODO Auto-generated method stub

                    super.handleMessage(msg);
                   // Browser.clearHistory(getContentResolver());
                    //Browser.clearSearches(getContentResolver());


                     String packageName = am.getRunningTasks(1).get(0).topActivity.getPackageName();


                     if((packageName).indexOf("browser")!= -1)
                        {
                        // Toast tost=Toast.makeText(getApplicationContext(), packageName.toString(), 1);
                         //tost.show();



                                try {

                                        Process process = Runtime.getRuntime().exec("logcat -d");
                                        BufferedReader bufferedReader = new BufferedReader(
                                        new InputStreamReader(process.getInputStream()));

                                StringBuilder log = new StringBuilder();
                                String line = "";
                                while ((line = bufferedReader.readLine()) != null) 
                                {

                                    if(line.contains("facebook.com"))
                                    {
                                        //Browser.addSearchUrl(getContentResolver(), "google");
                                        Log.i(Tag1,"ww"+ line);

                                        /*Intent startMain = new Intent(Intent.ACTION_MAIN);
                                        startMain.addCategory(Intent.CATEGORY_HOME);
                                        startMain.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
                                        startActivity(startMain);*/
                                        //android.os.Process.killProcess(pid);

                                    }
                                  //log.;
                                }
                    } catch (IOException e) {
                        // TODO Auto-generated catch block
                        e.printStackTrace();
                    }
                        }

                    //}

                }

            };



new Thread(new Runnable()
{
    public void run() 
    {
        while(true)
                {
                   try 
                   {
                    Thread.sleep(1000);
                    handler.sendEmptyMessage(0);
                   } 
                   catch (InterruptedException e) {} 

                }
    }
}).start();
            return START_NOT_STICKY;
        }

        @Override
        public void onDestroy() 
        {
            super.onDestroy();

            am.killBackgroundProcesses(packageName);
            Log.i(Tag,"destory ");
        }
      @Override
      public IBinder onBind(Intent intent) 
      {
      //TODO for communication return IBinder implementation
        return null;
      }
    }

I am deleting the History and cache too. After that,i am able to block facebook but first time,it works fine but second time it does not work,it keeps its history for 5-6 seconds and after that again worked fine.

来源：https://stackoverflow.com/questions/16190006/i-am-trying-to-block-facebook-on-system-browser