android 中查看当前是否联网
方法如下：
ConnectivityManager cwjManager=(ConnectivityManager)getSystemService(Context.CONNECTIVITY_SERVICE);NetworkInfo info = cwjManager.getActiveNetworkInfo();if (info != null && info.isAvailable()){//正常操作}else{//不能联网AlertDialog.Builder builder= new AlertDialog.Builder(this);builder.setTitle("出错啦").setMessage("当前操作需要联网，请配置网络连接后，重试！").setPositiveButton("确定", new DialogInterface.OnClickListener(){public void onClick(DialogInterface dialog,int which){SysApplication.getInstance().exit();}}).show();}同时需要在AndroidManifest.xml中进行配置
<uses-permission android:name=”android.permission.ACCESS_NETWORK_STATE”/>
