PHP SPL库

SPL，PHP 标准库（Standard PHP Library） ，此从 PHP 5.0 起内置的组件和接口，并且从 PHP5.3 已逐渐的成熟。SPL 其实在所有的 PHP5 开发环境中被内置，同时无需任何设置。

一.spl_autoload_register

更加方便的惰性加载

二.Iterator:迭代器

迭代器是比较重要的一种设计模式.普遍用于数组遍历.php的Iterator接口,预定义了以下方法:

Iterator extends Traversable {
	/* 方法 */
	abstract public mixed current ( void )
	abstract public scalar key ( void )
	abstract public void next ( void )
	abstract public void rewind ( void )
	abstract public boolean valid ( void )
}

　

任何类只要实现了该接口,则该类就可以迭代:
示例代码:

class Users implements Iterator
{
    protected $position = 0;
    protected $storage = array();

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

    public function getWithData()
    {
        $this->storage[] = array(
            array('id' => 1, 'name' => 'john'),
            array('id' => 2, 'name' => 'jake')
        );
    }

    public function current()
    {
        return $this->storage[$this->position];
    }

    public function next()
    {
        $this->position ++;
    }

    public function key()
    {
        return $this->position;
    }

    public function valid()
    {
        return isset($this->storage[$this->position]);
    }

    public function rewind()
    {
        $this->position = 0;
    }

}

$users = new Users();
foreach ($users as $key => $value) {
    echo $key;
    var_dump($value);
}

$users->rewind();

// 或者
while ($users->valid()) {
    $cur = $users->current();
    $users->next();
    var_dump($cur);
}

　　

SPL内置的迭代器类,可以方便的实现一些功能,比如迭代一个文件夹:

RecursiveIterator
RecursiveIteratorIterator
OuterIterator
IteratorIterator
FilterIterator
RecursiveFilterIterator
ParentIterator
SeekableIterator
LimitIterator
GlobIterator
CachingIterator
RecursiveCachingIterator
NoRewindIterator
AppendIterator
RecursiveIteratorIterator
InfiniteIterator
RegexIterator
RecursiveRegexIterator
EmptyIterator
RecursiveTreeIterator
ArrayIterator

　　

ps:
注意区分ArrayIterator和ArrayAccess的区别;
ArrayAccess:提供像访问数组一样访问对象的能力的接口

三.ArrayAccess接口:

ArrayAccess {
/* 方法 */
abstract public boolean offsetExists ( mixed $offset )
abstract public mixed offsetGet ( mixed $offset )
abstract public void offsetSet ( mixed $offset , mixed $value )
abstract public void offsetUnset ( mixed $offset )
}

　　

示例代码(结合单例模式):

class Config implements ArrayAccess
{
    private static $instance = null;
    private $configs;

    private function __construct()
    {
        $this->configs = array(
            'db_type' => 'mysql',
            'db_user' => 'root'
        );
    }

    public static function getInstance()
    {
        if (is_null(self::$instance)) {
            self::$instance = new Config();
        }
        return self::$instance;
    }

    public function offsetExists($offset)
    {
        return isset($this->configs[$offset]);
    }

    public function offsetGet($offset)
    {
        return $this->configs[$offset];
    }

    public function offsetSet($offset, $value)
    {
        $this->configs[$offset] = $value;
    }

    public function offsetUnset($offset)
    {
        unset($this->configs[$offset]);
    }

    public function __toString()
    {
        return (string)var_export($this->configs, true);
    }

    private function __clone()
    {
    }
}

$config = Config::getInstance();
print $config['db_type'];
print "\n";
$config['db_pwd'] = '1123';
print $config;

　　

四.SplFixedArray

SplFixedArray 实例化一个固定长度的数组.SplFixedArray数组相比标准的PHP数组更接近于C语言的数组，而且由于splFixedArray没有使用散列(Hash)存储方式，因此效率更高.