如何使外部类对象（在类外部实例化）可供php中的任何其他类访问

有4个文件，database.php、encryption.php、notify.php和index.php。前3个文件仅实例化一次。它们可以在任何文件或类中调用。如何调用或访问在类外部实例化的类的对象。例如：

# database.php #
class Database
{
    public function connect(){ //code }
    public function select(){ //code }
    public function insert(){ //code }
    public function update(){ //code }
    public function delete(){ //code }
}

# encryption.php #
class Crypt
{
    public function encrypt(){ //code }
    public function decrypt(){ //code }
}

# notify.php #
class notify
{
    public function setNotify(){ //code }
    public function getNotify(){ //code }
}

# index.php #
include ('database.php');
include ('encryption.php');
include ('notify.php');
$db = new Database();
$crypt = new Crypt();
$notify = new notify();

class one
{
    function execute()
    {
        $db->select(); // $db is the external object of Database class (database.php)
        $notify->setNotify(); // $notify is the external object of Notify class (notify.php)
    }
    function store()
    {
        $db->insert(); // $db is the external object of Database class (database.php)
        $notify->setNotify(); // $notify is the external object of Notify class (notify.php)
    }

}

class two
{
    function cypher()
    {
        $crypt->encrypt(); // $crypt is the external object of Crypt class (crypt.php)
        $db->update(); // $db is the external object of Database class (database.php)
        $notify->setNotify(); // $notify is the external object of Notify class (notify.php)
    }

}

$one = new one();
$two = new two();
$one->execute();
$two->cypher();
$one->store();

---

是在index.php中的类1和类2之外实例化的对象。如何访问

一类{}

和

二类{}

中的对象

$db

、

$crypt

和

$notify

？如何使这些对象像一个全局对象一样工作？

您要寻找的是一个全局对象。在软件中引入全局状态时要小心，因为它以后可能会导致问题

针对您的特定问题的一种可能的解决方案：

$db = new Database();
$crypt = new Crypt();
$notify = new notify();

---

请注意，php5.4+中提供了“可调用”类型提示，这可以通过依赖项注入来完成。你可以找到几个例子。

class SingletonManager
{

/**
 * Stores singleton instances
 * @var array
 */
protected static $_instances = array();

/**
 * Used to instantiate singletons
 * @param callable $factoryMethod
 * @return object of type returned by $factoryMethod or null
 */
public static function factory(callable $factoryMethod)
{
    /**
     * @var object
     */
    $singleton = $factoryMethod();
    // save reference to created object
    self::$_instances[get_class($singleton)] = $singleton;
    // return object
    return $singleton;
}

/**
 * Returns singleton object
 * @param string $className
 * @return object|null
 */
public static function instance($className)
{
    // check if there is an instance of $className
    if (isset(self::$_instances[$className])) {
        return self::$_instances[$className];
    }

    return null;
}

}
// end class definition

// mock database class
class Database
{
    public $username = '';
}

// create database object for the first time
SingletonManager::factory(function(){
    $database = new Database();
    $database->username = "username";
    return $database;
});

// access database object later from anywhere
$databaseObject = SingletonManager::instance("Database");
print_r($databaseObject);