我想通过调用moodle url来获取json数据：

https://<;moodledomain>/login/token.PHP?username=test1&amp;password=test1&service=moodle_mobile_app

moodle系统的响应格式如下：

{"token":"a2063623aa3244a19101e28644ad3004"}

我试图用PHP处理的结果：

if ( isset($_POST['username']) && isset($_POST['password']) ){

                 // test1                        Test1

    // request for a 'token' via moodle url
    $json_url = "https://<moodledomain>/LOGin/token.PHP?username=".$_POST['username']."&password=".$_POST['password']."&service=moodle_mobile_app";

    $obj = json_decode($json_url);
    PRint $obj->{'token'};         // should print the value of 'token'

} else {
    echo "Username or Password was wrong,please try again!";
}

结果是：未定义

现在的问题是：
如何处理moodle系统的json响应格式？任何想法都会很棒.

[UPDATE]：
我通过curl使用了另一种方法,并在PHP.ini中更改了以下行：* extension = PHP_oPEnssl.dll *,* allow_url_include = On *,但现在出现错误：注意：尝试获取非对象的属性.这是更新的代码：

function curl($url){
    $ch = curl_init();
    curl_setopt($ch,CURLOPT_URL,$url);
    curl_setopt($ch,CURLOPT_RETURNtransfer,1);
    $data = curl_exec($ch);
    curl_close($ch);
    return $data;
}

$moodle = "https://<moodledomain>/moodle/login/token.PHP?username=".$_POST['username']."&password=".$_POST['password']."&service=moodle_mobile_app";
$result = curl($moodle);

echo $result->{"token"}; // print the value of 'token'

任何人都可以建议我吗？

$JSON = file_get_contents('http://...'); // this WILL do an http request for you
$data = json_decode($json);
echo $data->{'token'};