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php教程之魔术方法的使用示例


 这篇文章主要介绍了php的魔术方法的使用示例(php魔术函数),需要的朋友可以参考下

 代码如下:

/** PHP把所有以__(两个下划线)开头的类方法当成魔术方法。所以你定义自己的类方法时,不要以 __为前缀。 * */

 

// __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"; 

/**

  输出结果如下:

  __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"; 

/**

 输出结果如下:

 __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可以把变量包括对象,转化成连续bytes数据. 你可以将串行化后的变量存在一个文件里或在网络上传输. 

  然后再反串行化还原为原来的数据. 你在反串行化类的对象之前定义的类,PHP可以成功地存储其对象的属性和方法. 

  有时你可能需要一个对象在反串行化后立即执行. 为了这样的目的,PHP会自动寻找__sleep和__wakeup方法.

  当一个对象被串行化,PHP会调用__sleep方法(如果存在的话). 在反串行化一个对象后,PHP 会调用__wakeup方法. 

  这两个方法都不接受参数. __sleep方法必须返回一个数组,包含需要串行化的属性. PHP会抛弃其它属性的值. 

  如果没有__sleep方法,PHP将保存所有属性.下面的例子显示了如何用__sleep和__wakeup方法来串行化一个对象. 

  Id属性是一个不打算保留在对象中的临时属性. __sleep方法保证在串行化的对象中不包含id属性. 

  当反串行化一个User对象,__wakeup方法建立id属性的新值. 这个例子被设计成自我保持. 

  在实际开发中,你可能发现包含资源(如图像或数据流)的对象需要这些方法

 */

 

class User {

 

    public $name;

    public $id;

 

    function __construct() {

        //give user a unique ID 赋予一个差别 的ID

        $this->id = uniqid();

    }

 

    //__sleep返回值的类型是数组,数组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 成立一个器材

$u = new User;

$u->name = "Leon"; //serialize it 串行化 留意不串行化id属性,id的值被遗弃

$s = serialize($u);

echo "__sleep, __wakeup, s: $s"; //unserialize it 反串行化 id被重新赋值

$u2 = unserialize($s); //$u and $u2 have different IDs $u和$u2有差别 的ID

print_r($u);

print_r($u2);

echo "nn"; 

/**

 输出结果如下:

  __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打印出来是数组,而不是调用时传递的对象

        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"; 

/**

  输出结果如下:

  __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";

/**

 输出结果如下:

 __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

  )) 

 */

 

www.phpzy.comtrue/php/29071.htmlTechArticlephp教程之魔术方法的使用示例 这篇文章主要介绍了php的魔术方法的使用示例(php魔术函数),需要的朋友可以参考下 代码如下: /** PHP把所有以__(两个下划线)开头的类方法当成魔术方法。...

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