php教程之魔術方法的使用示例

 這篇文章主要介紹了php的魔術方法的使用示例(php魔術函數),需要的朋友可以參考下

 代碼如下: /** PHP把所有以__（兩個下劃線）開頭的類方法當成魔術方法。所以你定義自己的類方法時，不要以 __為前綴。 * */   // __toString、__set、__get__isset()、__unset() /*   The __toString method allows a class to decide how it will react when it is converted to a string.   __set() is run when writing data to inaccessible members.   __get() is utilized for reading data from inaccessible members.   __isset() is triggered by calling isset() or empty() on inaccessible members.   __unset() is invoked when unset() is used on inaccessible members.  */ class TestClass {       private $data = array();     public $foo;       public function __construct($foo) {         $this->foo = $foo;     }       public function __toString() {         return $this->foo;     }       public function __set($name, $value) {         echo "__set, Setting '$name' to '$value'n";         $this->data[$name] = $value;     }       public function __get($name) {         echo "__get, Getting '$name'n";         if (array_key_exists($name, $this->data)) {             return $this->data[$name];         }     }       /** As of PHP 5.1.0 */     public function __isset($name) {         echo "__isset, Is '$name' set?n";         return isset($this->data[$name]);     }       /** As of PHP 5.1.0 */     public function __unset($name) {         echo "__unset, Unsetting '$name'n";         unset($this->data[$name]);     }   }   $obj = new TestClass('Hello'); echo "__toString, $objn"; $obj->a = 1; echo $obj->a . "nn"; var_dump(isset($obj->a)); unset($obj->a); var_dump(isset($obj->a)); echo "nn";  /**   輸出結果如下：   __toString, Hello   __set, Setting 'a' to '1'   __get, Getting 'a'   __isset, Is 'a' set?   bool(true)   __unset, Unsetting 'a'   __isset, Is 'a' set?   bool(false)  **/       // __call  __callStatic /*   mixed __call ( string $name , array $arguments )   mixed __callStatic ( string $name , array $arguments )   __call() is triggered when invoking inaccessible methods in an object context.   __callStatic() is triggered when invoking inaccessible methods in a static context.   The $name argument is the name of the method being called.   The $arguments argument is an enumerated array containing the parameters passed to the $name'ed method.  */ class MethodTest {     public function __call($name, $arguments) {         // Note: value of $name is case sensitive.         echo "__call, Calling object method '$name' " . implode(', ', $arguments) . "n";     }       /** As of PHP 5.3.0 */     public static function __callStatic($name, $arguments) {         // Note: value of $name is case sensitive.         echo "__callStatic, Calling static method '$name' " . implode(', ', $arguments) . "n";     }   }   $obj = new MethodTest; $obj->runTest('in object context', 'param2', 'param3'); //MethodTest::runTest('in static context'); // As of PHP 5.3.0 echo "nn";  /**  輸出結果如下：  __call, Calling object method 'runTest' in object context, param2, param3   string(10) "__invoke: "  */       // __invoke /*    The __invoke method is called when a script tries to call an object as a function.   Note: This feature is available since PHP 5.3.0. */ class CallableClass {     function __invoke($x) {         var_dump($x);     } }   $obj = new CallableClass; //$obj(5); var_dump('__invoke: ' . is_callable($obj)); echo "nn";            // __sleep  __wakeup /*   串行化serialize可以把變量包括對象,轉化成連續bytes數據. 你可以將串行化後的變量存在一個文件裡或在網絡上傳輸.    然後再反串行化還原為原來的數據. 你在反串行化類的對象之前定義的類,PHP可以成功地存儲其對象的屬性和方法.    有時你可能需要一個對象在反串行化後立即執行. 為了這樣的目的,PHP會自動尋找__sleep和__wakeup方法.   當一個對象被串行化,PHP會調用__sleep方法(如果存在的話). 在反串行化一個對象後,PHP 會調用__wakeup方法.    這兩個方法都不接受參數. __sleep方法必須返回一個數組,包含需要串行化的屬性. PHP會拋棄其它屬性的值.    如果沒有__sleep方法,PHP將保存所有屬性.下面的例子顯示了如何用__sleep和__wakeup方法來串行化一個對象.    Id屬性是一個不打算保留在對象中的臨時屬性. __sleep方法保證在串行化的對象中不包含id屬性.    當反串行化一個User對象,__wakeup方法建立id屬性的新值. 這個例子被設計成自我保持.    在實際開發中,你可能發現包含資源(如圖像或數據流)的對象需要這些方法  */   class User {       public $name;     public $id;       function __construct() {         //give user a unique ID 賦予一個差別 的ID         $this->id = uniqid();     }       //__sleep返回值的類型是數組，數組中的值是不需要串型化的字段id       function __sleep() {         //do not serialize this->id 不串行化id         return(array("name"));     }       function __wakeup() {         //give user a unique ID         $this->id = uniqid();     }   }   //create object 成立一個器材 $u = new User; $u->name = "Leon"; //serialize it 串行化 留意不串行化id屬性,id的值被遺棄 $s = serialize($u); echo "__sleep, __wakeup, s: $s"; //unserialize it 反串行化 id被重新賦值 $u2 = unserialize($s); //$u and $u2 have different IDs $u和$u2有差別 的ID print_r($u); print_r($u2); echo "nn";  /**  輸出結果如下：   __sleep, __wakeup, s: O:4:"User":1:{s:4:"name";s:4:"Leon";}   User Object   (   [name] => Leon   [id] => 4db1b17640da1   )   User Object   (   [name] => Leon   [id] => 4db1b17640dbc   )  */     // __set_state /*   This static method is called for classes exported by var_export() since PHP 5.1.0.   The only parameter of this method is an array containing exported properties in the form array('property' => value, ...).  */   class A {       public $var1;     public $var2;       public static function __set_state($an_array) { // As of PHP 5.1.0         //$an_array打印出來是數組，而不是調用時傳遞的對象         print_r($an_array);         $obj = new A;         $obj->var1 = $an_array['var1'];         $obj->var2 = $an_array['var2'];         return $obj;     }   }   $a = new A; $a->var1 = 5; $a->var2 = 'foo'; echo "__set_state:n"; eval('$b = ' . var_export($a, true) . ';');  // $b