PHP - 访问类的所有函数中的全局变量

$globalVar = "I am a global variable!";

function test() {
    global $globalVar;
    echo $globalVar;
}

test(); // 输出 "I am a global variable!"

$GLOBALS['globalVar'] = "I am a global variable!";

function test() {
    echo $GLOBALS['globalVar'];
}

test(); // 输出 "I am a global variable!"

function test() {
    static $globalVar = "I am a global variable!";
    echo $globalVar;
}

test(); // 输出 "I am a global variable!"

class MyClass {
    public static $globalVar = "I am a global variable!";

    public function test() {
        echo self::$globalVar;
    }
}

$obj = new MyClass();
$obj->test(); // 输出 "I am a global variable!"