PHP类中的魔术方法（Magic Method）简明总结

1. __construct()和__destruct()

在实例被 创建/销毁 的时候被调用，都可以传递0个或多个参数。

class A {  function A()  {   echo "build A";  }  function __destruct()  {   echo "destroy A";  } } $obj = new A(); //unset($obj);

Note：The destructor method will be called as soon as there are no other references to a particular object, or in any order during the shutdown sequence.

　　关于构造函数，PHP5.3.3开始，一个定义在某个特定的命名空间里的class中以类名命名的方法将不再被认为是构造函数。在无命名空间的类中与原来一样依旧是构造函数。如：

namespace Foo;class Bar {  public function Bar() {    // treated as constructor in PHP 5.3.0-5.3.2    // treated as regular method as of PHP 5.3.3  }}

如果没有namespace Foo; 那么Bar()还将被当作构造函数。另外，如果存在下面的情况：

function __construct()  {   echo "construct A";  }  function A()  {   echo "build A";  }  function __destruct()  {   echo "destroy A";  } }

即既包含__construct()又包含与类名同名的函数，那么将只调用__construct()。

2. __call()和__callStatic()

当尝试调用一个不存在的方法时调用该方法。两个参数，一个是方法名，一个是被调用方法的参数数组。

class MethodTest{  public function __call($name, $arguments)  {    // Note: value of $name is case sensitive.    echo "Calling object method '$name' "       . implode(' ', $arguments). "<br>";  }  public static function __callStatic($name, $arguments)  {    // Note: value of $name is case sensitive.    echo "Calling static method '$name' "       . implode(' ', $arguments). "<br>";  }}$obj = new MethodTest;$obj->runTest('in','object','context');MethodTest::runTest('in','static','context');

其中，$arguments作为一个array传入。运行结果：

Calling object method 'runTest' in object context
Calling static method 'runTest' in static context

还要注意函数的作用域protected和private：

class TestMagicCallMethod {  public function foo()  {    echo __METHOD__.PHP_EOL."<br>";  }  public function __call($method, $args)  {    echo __METHOD__.PHP_EOL."<br>";    if(method_exists($this, $method))    {      $this->$method();    }  }    protected function bar()  {    echo __METHOD__.PHP_EOL."<br>";  }  private function baz()  {    echo __METHOD__.PHP_EOL."<br>";  }}$test  =  new TestMagicCallMethod();$test->foo();/** * Outputs: * TestMagicCallMethod::foo */$test->bar();/** * Outputs: * TestMagicCallMethod::__call * TestMagicCallMethod::bar */$test->baz();/** * Outputs: * TestMagicCallMethod::__call * TestMagicCallMethod::baz */

3.__get()和__set()