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。html' target='_blank'>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() 当试图读取一个对象并不存在的属性的时候被调用。 Note：我们可以用这个函数实现类似java中反射的各种操作。class Test public function __get($key) echo $key . " not exists"; public function __set($key,$value) echo $key . " = ".$value;$t = new Test();echo $t- name." br $t- name = "abc";输出： name not exists name = abc4. __toString() 这个方法类似于java的toString()方法，当我们直接打印对象的时候回调用这个函数，函数必须返回一个string。 class Test private $name = "abc"; private $age = 12; public function __toString() return "name : $this- name, age : $this- age";$t = new Test();echo $t;输出：name : abc, age : 12PHP教程
