一,public,private,protected的區別
public:權限是最大的,可以內部調用,實例調用等。
protected: 受保護類型,用於本類和繼承類調用。
private: 私有類型,只有在本類中使用。
二,實例
復制代碼 代碼如下:
<?php
error_reporting(E_ALL);
class test{
public $public;
private $private;
protected $protected;
static $instance;
public function __construct(){
$this->public = 'public <br>';
$this->private = 'private <br>';
$this->protected = 'protected <br>';
}
static function tank(){
if (!isset(self::$instance[get_class()]))
{
$c = get_class();
self::$instance = new $c;
}
return self::$instance;
}
public function pub_function() {
echo "you request public function<br>";
echo $this->public;
echo $this->private; //private,內部可以調用
echo $this->protected; //protected,內部可以調用
$this->pri_function(); //private方法,內部可以調用
$this->pro_function(); //protected方法,內部可以調用
}
protected function pro_function(){
echo "you request protected function<br>";
}
private function pri_function(){
echo "you request private function<br>";
}
}
$test = test::tank();
echo $test->public;
echo $test->private; //Fatal error: Cannot access private property test::$private
echo $test->protected; //Fatal error: Cannot access protected property test::$protected
$test->pub_function();
$test->pro_function(); //Fatal error: Call to protected method test::pro_function() from context
$test->pri_function(); //Fatal error: Call to private method test::pri_function() from context
?>
從上面的例子中,我們可以看出,
public: 可以class內部調用,可以實例化調用。
private: 可以class內部調用,實例化調用報錯。
protected: 可以class內部調用,實例化調用報錯。
復制代碼 代碼如下:
<?php
class test{
public $public;
private $private;
protected $protected;
static $instance;
public function __construct(){
$this->public = 'public <br>';
$this->private = 'private <br>';
$this->protected = 'protected <br>';
}
protected function tank(){ //私有方法不能繼承,換成public,protected
if (!isset(self::$instance[get_class()]))
{
$c = get_class();
self::$instance = new $c;
}
return self::$instance;
}
public function pub_function() {
echo "you request public function<br>";
echo $this->public;
}
protected function pro_function(){
echo "you request protected function<br>";
echo $this->protected;
}
private function pri_function(){
echo "you request private function<br>";
echo $this->private;
}
}
class test1 extends test{
public function __construct(){
parent::tank();
parent::__construct();
}
public function tank(){
echo $this->public;
echo $this->private; //Notice: Undefined property: test1::$private
echo $this->protected;
$this->pub_function();
$this->pro_function();
$this->pri_function(); //Fatal error: Call to private method test::pri_function() from context 'test1'
}
public function pro_extends_function(){
echo "you request extends_protected function<br>";
}
public function pri_extends_function(){
echo "you request extends_private function<br>";
}
}
error_reporting(E_ALL);
$test = new test1();
$test -> tank(); //子類和父類有相同名字的屬性和方法,實例化子類時,子類的中的屬性和方法會蓋掉父類的。
?>
從上面的例子中,我們可以看出,
public: test中的public可以被繼承。
private: test中的private不可以被繼承。
protected:test中的protected可以被繼承。
static: test中的static可以被繼承。
唉,對於這些東西,老是不喜歡記著,用的時候,總感覺不對,又要去查,所以寫個例子,方便自己查看。