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) . ';'); // $b = A::__set_state(array( // 'var1' => 5, // 'var2' => 'foo', // )); var_dump($b); echo "nn"; /** 輸出結果如下： __set_state: Array ( [var1] => 5 [var2] => foo ) object(A)#5 (2) { ["var1"]=> int(5) ["var2"]=> string(3) "foo" } */ // __clone class SubObject { static $instances = 0; public $instance; public function __construct() { $this->instance = ++self::$instances; } public function __clone() { $this->instance = ++self::$instances; } } class MyCloneable { public $object1; public $object2; function __clone() { // Force a copy of this->object, otherwise // it will point to same object. $this->object1 = clone $this->object1; } } $obj = new MyCloneable(); $obj->object1 = new SubObject(); $obj->object2 = new SubObject(); $obj2 = clone $obj; print("__clone, Original Object:n"); print_r($obj); print("__clone, Cloned Object:n"); print_r($obj2); echo "nn"; /** 輸出結果如下： __clone, Original Object: MyCloneable Object ( [object1] => SubObject Object ( [instance] => 1 ) [object2] => SubObject Object ( [instance] => 2 )) __clone, Cloned Object: MyCloneable Object ( [object1] => SubObject Object ( [instance] => 3 ) [object2] => SubObject Object ( [instance] => 2 )) */
