Android编程判断网络是否可用及调用系统设置项的方法

private boolean checkNetwork() {    boolean flag = false;    ConnectivityManager manager = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);    if (manager.getActiveNetworkInfo() != null)      flag = manager.getActiveNetworkInfo().isAvailable();    if (!flag) {      Builder b = new AlertDialog.Builder(this).setTitle("没有可用的网络").setMessage(          "请开启GPRS或WIFI网络连接");      b.setPositiveButton("确定", new DialogInterface.OnClickListener() {        public void onClick(DialogInterface dialog, int whichButton) {          Intent mIntent = new Intent("/");          ComponentName comp = new ComponentName("com.android.settings",              "com.android.settings.WirelessSettings");          mIntent.setComponent(comp);          mIntent.setAction("android.intent.action.VIEW");          startActivity(mIntent);        }      }).setNeutralButton("取消", new DialogInterface.OnClickListener() {        public void onClick(DialogInterface dialog, int whichButton) {          dialog.cancel();        }      }).create();      b.show();    }    return flag;}

<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" /><uses-permission android:name="android.permission.ACCESS_WIFI_STATE" />