1. __construct()和__destruct()
在實(shí)例被 創(chuàng)建/銷毀 的時(shí)候被調(diào)用，都可以傳遞0個(gè)或多個(gè)參數(shù)。
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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.
關(guān)于構(gòu)造函數(shù)，PHP5.3.3開(kāi)始，一個(gè)定義在某個(gè)特定的命名空間里的class中以類名命名的方法將不再被認(rèn)為是構(gòu)造函數(shù)。在無(wú)命名空間的類中與原來(lái)一樣依舊是構(gòu)造函數(shù)。如：
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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 }} |
如果沒(méi)有namespace Foo; 那么Bar()還將被當(dāng)作構(gòu)造函數(shù)。另外，如果存在下面的情況：
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function __construct() { echo "construct A"; } function A() { echo "build A"; } function __destruct() { echo "destroy A"; } } |
即既包含__construct()又包含與類名同名的函數(shù)，那么將只調(diào)用__construct()。
2. __call()和__callStatic()
當(dāng)嘗試調(diào)用一個(gè)不存在的方法時(shí)調(diào)用該方法。兩個(gè)參數(shù)，一個(gè)是方法名，一個(gè)是被調(diào)用方法的參數(shù)數(shù)組。
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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作為一個(gè)array傳入。運(yùn)行結(jié)果：
Calling object method 'runTest' in object context
Calling static method 'runTest' in static context
還要注意函數(shù)的作用域protected和private：
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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()
當(dāng)試圖讀取一個(gè)對(duì)象并不存在的屬性的時(shí)候被調(diào)用。
Note：我們可以用這個(gè)函數(shù)實(shí)現(xiàn)類似java中反射的各種操作。
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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"; |
輸出：
name not exists
name = abc
4. __toString()
這個(gè)方法類似于java的toString()方法，當(dāng)我們直接打印對(duì)象的時(shí)候回調(diào)用這個(gè)函數(shù)，函數(shù)必須返回一個(gè)string。
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class Test{ private $name = "abc"; private $age = 12; public function __toString() { return "name : $this->name, age : $this->age"; }}$t = new Test();echo $t; |
輸出：
name : abc, age : 12
