ReflectionClass::getConstants

(PHP 5, PHP 7)

ReflectionClass::getConstants — 获取一组常量

说明

public array ReflectionClass::getConstants ( void )

获取某个类的全部已定义的常量，不管可见性如何定义。

Warning

本函数还未编写文档，仅有参数列表。

参数

此函数没有参数。

返回值

常量的数组，常量名是数组的键，常量的值是数组的值。

参见

User Contributed Notes

Sandor Toth 21-Nov-2016 11:50
You can pass $this as class for the ReflectionClass. __CLASS__ won't help if you extend the original class, because it is a magic constant based on the file itself.

<?php

class Example {
  const TYPE_A = 1;
  const TYPE_B = 'hello';

  public function getConstants()
  {
    $reflectionClass = new ReflectionClass($this);
    return $reflectionClass->getConstants();
  }
}

$example = new Example();
var_dump($example->getConstants());

// Result:
array ( size = 2)
  'TYPE_A' => int 1
  'TYPE_B' => (string) 'hello'
davide dot renzi at gmail dot com 16-Jul-2014 08:21
If you want to return the constants defined inside a class then you can also define an internal method as follows:

<?php
class myClass {
    const NONE = 0;
    const REQUEST = 100;
    const AUTH = 101;

    // others...

    static function getConstants() {
        $oClass = new ReflectionClass(__CLASS__);
        return $oClass->getConstants();
    }
}
?>
shgninc at gmail dot com 20-Nov-2013 07:00
I use a functions to do somthing base on the class constant name as below. This example maybe helpful for everybody.
<?php
public function renderData($question_type = NULL, $data = array()) {
        $types = array();
        $qt = new ReflectionClass(questionType);
        $types = $qt->getConstants();
        if ($type = array_search($question_type, $types)){
                //.....Do somthing
}
}
?>
djhob1972 at yahoo dot com dot au 16-Dec-2009 02:42
I was trying to determine how to get a var_dump of constants that are within an interface.  Thats right, not using any classes but the interface itself.

Along my travels I found it quite interesting that the ReflectionClass along with a direct call to the interface will also dump its constants.  Perfect!!!!

This was using PHP 5.3.1 and my example as below:-

1st File:

constants.php

<?php
<?php>

interface MyConstants
{
    // --------------------------
    // Programmatic Level
    // --------------------------
    const DEBUG_MODE_ACTIVE       = FALSE;
    const PHP_VERSION_REQUIREMENT = "5.1.2";
}
?>

=======
Second file:
=======

test.php

<?php>
include_once ("constants.php");

$oClass = new ReflectionClass ('MyConstants');
$array = $oClass->getConstants ();
var_dump ($array);
unset ($oClass);
?>

what you would get from the command line:-

?:\???\htdocs\????>php test.php
array(2) {
  ["DEBUG_MODE_ACTIVE"]=> bool(false)
  ["PHP_VERSION_REQUIREMENT"]=> string(5) "5.1.2"

But as you can see this can work quite well to your advantage in many ways so I truely hope this helps someone else with a similar headache in the future to come!

Enjoy!