PHP5 has a complete reflection API, adding the ability to reverse engineer classes, interfaces, functions, methods and extensions.

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 include: automatically loading plug-ins, automatically generating 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.

We usually use the ReflectionClass class and ReflectionMethod class, for example:

<?php
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;
 public function 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;
 }
}

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

1. Constants
2. Property Names
3. Method Method Names static
4. Static Properties
5. Namespace
6. Whether the Person class is final or abstract
7. Whether the Person class has a certain method

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

$class = new ReflectionClass('Person'); // 建立 Person这个类的反射类  
$instance  = $class->newInstanceArgs($args); // 相当于实例化Person 类

1) Get properties (Properties):

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

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

$private_properties = $class->getProperties(ReflectionProperty::IS_PRIVATE);

Available parameter list:

ReflectionProperty::IS_STATIC
ReflectionProperty::IS_PUBLIC
ReflectionProperty::IS_PROTECTED
ReflectionProperty::IS_PRIVATE

You can get the attribute name through $property->getName().

2) Get comments:

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

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

3) Get the method of the class

getMethods()       来获取到类的所有methods。
hasMethod(string)  是否存在某个方法
getMethod(string)  获取方法

4) Execute the method of the class:

$instance->getName(); // 执行Person 里的方法getName
// 或者：
$method = $class->getmethod('getName'); // 获取Person 类中的getName方法
$method->invoke($instance);    // 执行getName 方法
// 或者：
$method = $class->getmethod('setName'); // 获取Person 类中的setName方法
$method->invokeArgs($instance, array('snsgou.com'));

2. Through ReflectionMethod, we can get the information of a certain method of the Person class:

1. Whether it is "public" or "protected" ”, “private”, “static” types
2. Parameter list of the method
3. Number of parameters of the method
4. Method of decalling the class

// 执行detail方法
$method = new ReflectionMethod('Person', 'test');
if ($method->isPublic() && !$method->isStatic()) {
 echo 'Action is right';
}
echo $method->getNumberOfParameters(); // 参数个数
echo $method->getParameters(); // 参数对象数组

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