php类中的$this，static，final，const，self这几个关键字使用方法

<?php
class MyClass{
 private $name;
 public function __construct($name){
 $this->name=$name;
 }
 public function getname(){
 return $this->name;
 }
 public function printName(){
 echo $this->getname();
 }
}
$myclass= new MyClass("I Like www.jb51.net");
$myclass->printName();//输出：I Like www.jb51.net
?>

static $val='';

<?php
class MyObject{
 public static $myStaticVar=0;
 function myMethod(){
 self::$myStaticVar+=2;
 echo self::$myStaticVar;
 }
}
$instance1=new MyObject();
$instance1->myMethod();
$instance2=new MyObject();
$instance2->myMethod();
　　//结果将分别打印2、4

<?php
class Book{
 static $num=0;
 public function showMe(){
 echo"您是滴".self::$num."位访客";
 self::$num++;
 }
}
$book1=new Book();
$book1->showMe();
echo"<br>";
$book2=new Book();
$book2->showMe();
echo"<br>";
echo"您是滴".Book::$num."位访客";
?>

final class MyClass{//此类将不允许被继承
　　final function fun1(){......}//此方法将不允许被重写
　　}

 < ?PHP  
  final class BaseClass {  
  public function test() {  
  echo "BaseClass::test() calledn";  
  }  
  final public function moreTesting() {  
  echo "BaseClass::moreTesting() calledn";  
  }  
  }  
  class ChildClass extends BaseClass {  
  public function moreTesting() {  
  echo "ChildClass::moreTesting() calledn";  
  }  
  }  
  // Results in Fatal error: Cannot override final method BaseClass::moreTesting()  
  ?> 

<?php
class clss_a{
 private static $name="static class_a"; 
 const PI=3.14; 
 public $value; 
 public static function getName(){ 
 return self::$name; 
 } 
 //这种写法有误，静态方法不能访问非静态属性 
 public static function getName2(){ 
 return self::$value; 
 } 
 public function getPI(){ 
 return self::PI; 
 }
}