ConnectivityManager判断是否有网络

/** * 检测是否开启wify或gprs * @param context * @return */public boolean checkNetwork(final Context context){        ConnectivityManager manager = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);        //mobile 3G Data Network        State mobile = manager.getNetworkInfo(ConnectivityManager.TYPE_MOBILE).getState();        //wifi        State wifi = manager.getNetworkInfo(ConnectivityManager.TYPE_WIFI).getState();                //如果3G网络和wifi网络都未连接，且不是处于正在连接状态 则进入Network Setting界面 由用户配置网络连接        if(mobile==State.CONNECTED||mobile==State.CONNECTING)            return true;        if(wifi==State.CONNECTED||wifi==State.CONNECTING)        return true;                        Builder b = new android.app.AlertDialog.Builder(context).setTitle("没有可用的网络").setMessage("请开启GPRS或WIFI网络连接");b.setPositiveButton("设置网络", new DialogInterface.OnClickListener() {public void onClick(DialogInterface dialog, int whichButton) {context.startActivity(new Intent(Settings.ACTION_WIRELESS_SETTINGS));//进入无线网络配置界面//context.startActivity(new Intent(Settings.ACTION_WIFI_SETTINGS)); //进入手机中的wifi网络设置界面}}).setNeutralButton("取消", new DialogInterface.OnClickListener() {public void onClick(DialogInterface dialog, int whichButton) {dialog.cancel();}}).create();b.show();return false;            }

App自动更新之通知栏下载
http://www.cnblogs.com/qianxudetianxia/archive/2011/04/12/2010919.html