联网判断

判断是否联网

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

private void getDoing() {
    final AlertDialog.Builder builder = new AlertDialog.Builder(HomeActivity.this);
    builder.setMessage("网络有误，请设置网络...");
    builder.setPositiveButton("确定", new DialogInterface.OnClickListener() {
        @Override
        public void onClick(DialogInterface dialogInterface, int i) {
            //跳转网络设置界面
            startActivity(new Intent(Settings.ACTION_WIRELESS_SETTINGS));
        }
    });
    builder.setNegativeButton("取消", new DialogInterface.OnClickListener() {
        @Override
        public void onClick(DialogInterface dialogInterface, int i) {
            select();
            alertDialog.dismiss();
        }
    });
    alertDialog = builder.create();
    alertDialog.show();
}

在AndroidManifext.xml添加访问当前网络的权限

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