abstract class Enumeration
{
    public static function enum() 
    {
        $reflect = new ReflectionClass( get_called_class() );
        return $reflect->getConstants();
    }
}


class Test extends Enumeration
{
    const A = 'a';
    const B = 'b';    
}


foreach (Test::enum() as $key => $value) {
    echo "$key -> $value<br>";
}

我也喜欢java的枚举，因此我这样写我的枚举，我认为这是最类似的行为像在java的枚举，当然，如果有人想使用更多的方法从java应该写在这里，或在抽象类，但核心思想是嵌入在下面的代码

class FruitsEnum {

    static $APPLE = null;
    static $ORANGE = null;

    private $value = null;

    public static $map;

    public function __construct($value) {
        $this->value = $value;
    }

    public static function init () {
        self::$APPLE  = new FruitsEnum("Apple");
        self::$ORANGE = new FruitsEnum("Orange");
        //static map to get object by name - example Enum::get("INIT") - returns Enum::$INIT object;
        self::$map = array (
            "Apple" => self::$APPLE,
            "Orange" => self::$ORANGE
        );
    }

    public static function get($element) {
        if($element == null)
            return null;
        return self::$map[$element];
    }

    public function getValue() {
        return $this->value;
    }

    public function equals(FruitsEnum $element) {
        return $element->getValue() == $this->getValue();
    }

    public function __toString () {
        return $this->value;
    }
}
FruitsEnum::init();

var_dump(FruitsEnum::$APPLE->equals(FruitsEnum::$APPLE)); //true
var_dump(FruitsEnum::$APPLE->equals(FruitsEnum::$ORANGE)); //false
var_dump(FruitsEnum::$APPLE instanceof FruitsEnum); //true
var_dump(FruitsEnum::get("Apple")->equals(FruitsEnum::$APPLE)); //true - enum from string
var_dump(FruitsEnum::get("Apple")->equals(FruitsEnum::get("Orange"))); //false

// My Enumeration Class
class Enum
{
    protected $m_actions = array();

    public function __construct($actions)
    {
        $this->init($actions);
    }

    public function init($actions)
    {
        $this->m_actions = array();
        for($i = 0; $i < count($actions); ++$i)
        {
            $this->m_actions[$actions[$i]] = ($i + 1); 
            define($actions[$i], ($i + 1));
        }
    }

    public function toString($index)
    {
        $keys = array_keys($this->m_actions);
        for($i = 0; $i < count($keys); ++$i)
        {
            if($this->m_actions[$keys[$i]] == $index)
            {
                return $keys[$i];
            }
        }

        return "undefined";
    }

    public function fromString($str)
    {
        return $this->m_actions[$str];
    }
}

// Enumeration creation
$actions = new Enum(array("CREATE", "READ", "UPDATE", "DELETE"));

// Examples
print($action_objects->toString(DELETE));
print($action_objects->fromString("DELETE"));

if($action_objects->fromString($_POST["myAction"]) == CREATE)
{
    print("CREATE");
}

四年后，我又遇到了这个。我目前的方法是这样的，因为它允许在IDE中完成代码以及类型安全:

基类:

abstract class TypedEnum
{
    private static $_instancedValues;

    private $_value;
    private $_name;

    private function __construct($value, $name)
    {
        $this->_value = $value;
        $this->_name = $name;
    }

    private static function _fromGetter($getter, $value)
    {
        $reflectionClass = new ReflectionClass(get_called_class());
        $methods = $reflectionClass->getMethods(ReflectionMethod::IS_STATIC | ReflectionMethod::IS_PUBLIC);    
        $className = get_called_class();

        foreach($methods as $method)
        {
            if ($method->class === $className)
            {
                $enumItem = $method->invoke(null);

                if ($enumItem instanceof $className && $enumItem->$getter() === $value)
                {
                    return $enumItem;
                }
            }
        }

        throw new OutOfRangeException();
    }

    protected static function _create($value)
    {
        if (self::$_instancedValues === null)
        {
            self::$_instancedValues = array();
        }

        $className = get_called_class();

        if (!isset(self::$_instancedValues[$className]))
        {
            self::$_instancedValues[$className] = array();
        }

        if (!isset(self::$_instancedValues[$className][$value]))
        {
            $debugTrace = debug_backtrace();
            $lastCaller = array_shift($debugTrace);

            while ($lastCaller['class'] !== $className && count($debugTrace) > 0)
            {
                $lastCaller = array_shift($debugTrace);
            }

            self::$_instancedValues[$className][$value] = new static($value, $lastCaller['function']);
        }

        return self::$_instancedValues[$className][$value];
    }

    public static function fromValue($value)
    {
        return self::_fromGetter('getValue', $value);
    }

    public static function fromName($value)
    {
        return self::_fromGetter('getName', $value);
    }

    public function getValue()
    {
        return $this->_value;
    }

    public function getName()
    {
        return $this->_name;
    }
}

枚举例子:

final class DaysOfWeek extends TypedEnum
{
    public static function Sunday() { return self::_create(0); }    
    public static function Monday() { return self::_create(1); }
    public static function Tuesday() { return self::_create(2); }   
    public static function Wednesday() { return self::_create(3); }
    public static function Thursday() { return self::_create(4); }  
    public static function Friday() { return self::_create(5); }
    public static function Saturday() { return self::_create(6); }      
}

使用示例:

function saveEvent(DaysOfWeek $weekDay, $comment)
{
    // store week day numeric value and comment:
    $myDatabase->save('myeventtable', 
       array('weekday_id' => $weekDay->getValue()),
       array('comment' => $comment));
}

// call the function, note: DaysOfWeek::Monday() returns an object of type DaysOfWeek
saveEvent(DaysOfWeek::Monday(), 'some comment');

注意，同一个枚举条目的所有实例都是相同的:

$monday1 = DaysOfWeek::Monday();
$monday2 = DaysOfWeek::Monday();
$monday1 === $monday2; // true

你也可以在switch语句中使用它:

function getGermanWeekDayName(DaysOfWeek $weekDay)
{
    switch ($weekDay)
    {
        case DaysOfWeek::Monday(): return 'Montag';
        case DaysOfWeek::Tuesday(): return 'Dienstag';
        // ...
}

你也可以通过名称或值创建枚举项:

$monday = DaysOfWeek::fromValue(2);
$tuesday = DaysOfWeek::fromName('Tuesday');

或者你可以从一个现有的枚举条目中获取名称(即函数名):

$wednesday = DaysOfWeek::Wednesday()
echo $wednesDay->getName(); // Wednesday

现在您可以使用The脾脏类来原生构建它。根据官方文件。

脾提供了模拟和创建枚举对象的能力 原生的PHP。

<?php
class Month extends SplEnum {
    const __default = self::January;

    const January = 1;
    const February = 2;
    const March = 3;
    const April = 4;
    const May = 5;
    const June = 6;
    const July = 7;
    const August = 8;
    const September = 9;
    const October = 10;
    const November = 11;
    const December = 12;
}

echo new Month(Month::June) . PHP_EOL;

try {
    new Month(13);
} catch (UnexpectedValueException $uve) {
    echo $uve->getMessage() . PHP_EOL;
}
?>

请注意，这是一个必须安装的扩展，但默认情况下不可用。在PHP网站上描述的特殊类型下。上面的示例取自PHP站点。

类常量呢?

<?php

class YourClass
{
    const SOME_CONSTANT = 1;

    public function echoConstant()
    {
        echo self::SOME_CONSTANT;
    }
}

echo YourClass::SOME_CONSTANT;

$c = new YourClass;
$c->echoConstant();