1. Introduction

-- PHP5 adds a new feature: Reflection. This feature enables PHP to reverse-engineer class, interface, function, method and extension. Through PHP code, you can get all the information of an object and interact with it.

-- What is reflection?

It refers to extending the analysis of PHP programs in the running state of PHP and exporting or extracting detailed information about classes, methods, properties, parameters, etc., including comments. This function of dynamically obtaining information and dynamically calling methods of objects is called reflection API. Reflection is an API for manipulating meta-models in the Object-oriented paradigm. It is very powerful and can help us build complex and scalable applications.

Its uses are: Automatically load plug-ins, automatically generate documents, and can even be used to expand the PHP language.

The PHP reflection API consists of several classes that help us access the metadata of the program or interact with related annotations. With the help of reflection, we can obtain the methods implemented by the class, create an instance of the class (different from creating with new), call a method (also different from the regular call), pass parameters, and dynamically call the static methods of the class.

Reflection API is PHP's built-in OOP technology extension, including some classes, exceptions and interfaces. Used together, they can be used to help us analyze other classes, interfaces, methods, properties, methods and extensions. These oop extensions are called reflection.

Through ReflectionClass, we can get the following information of the Person class:

1) Constant Contents

2) Property Property Names

3) Method Names Static

4) Properties Static Properties

5) Namespace Namespace

6) Whether the Person class is final or abstract

2. Specific example

Create a Person class and then use ReflectionClass to reflect it

2.1) [Create Persion class]

class Person { 
 /** 
   * For the sake of demonstration, we"re setting this private
   */
 private $_allowDynamicAttributes = false; 
 /** type=primary_autoincrement */
 protected $id = 0; 
 /** type=varchar length=255 null */
 protected $name; 
 /** type=text null */
 protected $biography; 
 publicfunction getId() 
   { 
 return $this->id; 
   } 
 public function setId($v) 
   { 
 $this->id = $v; 
   } 
 public function getName() 
   { 
 return $this->name; 
   } 
 public function setName($v) 
   { 
 $this->name = $v; 
   } 
 public function getBiography() 
   { 
 return $this->biography; 
   } 
 public function setBiography($v) 
   { 
 $this->biography = $v; 
   } 
 }
Persion

2.2) [Reflection Process]

Next to reflect it, just pass the class name "Person" to ReflectionClass. ：

$class = new ReflectionClass('Person');//建立 Person這個(gè)類的反射類
$instance = $class->newInstanceArgs($args);//相當(dāng)于實(shí)例化Person 類

2.3) [Use after reflection]

2.3.1) Get properties (Properties)

$properties = $class->getProperties(); 
 foreach($properties as $property) { 
 echo $property->getName()."\n"; 
 } 
 // 輸出:
 // _allowDynamicAttributes
 // id
 // name
 // biography

By default, ReflectionClass will obtain all properties, including private and protected ones. If you only want to get private properties, you need to pass an additional parameter:

privateproperties=privateproperties=class->getProperties(ReflectionProperty::IS_PRIVATE);

Available Parameter list:

• ReflectionProperty::IS_STATIC

• ReflectionProperty::IS_PUBLIC

• ReflectionProperty:: IS_PROTECTED

• ReflectionProperty::IS_PRIVATE

#If you want to get both public and private properties, write like this: ReflectionProperty::IS_PUBLIC | ReflectionProperty:: IS_PROTECTED.

The property name can be obtained through $property->getName().

2.3.2) [Get comments]

You can get the comments written to the property through getDocComment.

foreach($propertiesas$property) { 
 if($property->isProtected()) { 
 $docblock = $property->getDocComment(); 
   preg_match('/ type\=([a-z_]*) /', $property->getDocComment(), $matches); 
 echo$matches[1]."\n"; 
  } 
 } 
 // Output:
 // primary_autoincrement
 // varchar
 // text

2.3.3) [Get methods of class]

Get methods (methods): Get all methods of the class through getMethods().

2.3.4) [Execution class method]

 $instance->getBiography(); //執(zhí)行Person 里的方法getBiography
 //或者：
 $ec=$class->getmethod('getName'); //獲取Person 類中的getName方法
 $ec->invoke($instance);  //執(zhí)行g(shù)etName 方法

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