Android网络判断

判断IsOnline如果为true 有网就做有网的判断， 否则的好没网就会单出对话框 

 @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        if(isOnline()) {            //有网，联网请求数据网络的执行方法           // getData();        }else{            //弹出提示对话框            showDialog();        }    }

这个方法是做的是判断数据是有网还是没网的状态

public boolean isOnline() {        //得到一个连接管理者        ConnectivityManager connMgr = (ConnectivityManager)getSystemService(Context.CONNECTIVITY_SERVICE);        //得到联网信息        NetworkInfo networkInfo = connMgr.getActiveNetworkInfo();        //判断设备是否联网        return (networkInfo != null && networkInfo.isConnected());    }

弹出对话框做联网还是不联网

    private void showDialog(){        AlertDialog.Builder builder = new AlertDialog.Builder(this);        builder.setMessage("怎么可没网呢");        builder.setNegativeButton("不联网，",new DialogInterface.OnClickListener() {            @Override            public void onClick(DialogInterface dialog, int which) {                //不连接网络                           }        });        builder.setPositiveButton("联网", new DialogInterface.OnClickListener() {            @Override            public void onClick(DialogInterface dialog, int which) {                //跳转网络设置界面                startActivity(new Intent(Settings.ACTION_WIRELESS_SETTINGS));            }        });        builder.create().show();    }