IImage--factory

<?php
/* 实例4 */
/* 使用工厂类解析图像工作 */
interface IImage {
    function getWidth();
    function getHeight();
    function getData();
}
class Image_PNG implements IImage {
    protected $_width, $height, $_data;

    public function __construct($file) {
        $this->_file = $file;
        $this->_parse();
    }

    private function _parse() {
        //完成PNG格式的解析工作
        //并填充$_width, $_height, $_data
        $this->_data = getimagesize($this->_file);
        list($this->_width, $this->_height) = $this->_data;
    }

    public function getWidth() {
        return $this->_width;
    }

    public function getHeight() {
        return $this->_height;
    }

    public function getData() {
        return $this->_data;
    }
}
class Image_JPGE implements IImage {

    protected $_width, $_height, $_data;

    public function __construct($file) {
        $this->_file = $file;
        $this->_parse();
    }

    private function _parse() {
        //完成JPGE格式的解析工作
        //并填充$_width, $_height, $_data
        //$this->_width = imagesx($this->_file);
        //$this->_height = imagesx($this->_file);
        $this->_data = getimagesize($this->_file);
        list($this->_width, $this->_height) = $this->_data;
    }

    public function getWidth(){
        return $this->_width;
    }

    public function getHeight(){
        return $this->_height;
    }

    public function getData() {
        return $this->_data;
    }
}
class ImageFactory {
    public static function factory($file) {
        $filename = pathinfo($file);
        switch(strtolower($filename['extension'])){
            case 'jpg':
                $return = new Image_JPEG($file);
                break;
            case 'png':
                $return = new Image_PNG($file);
                break;
            default:
                echo '图片类型不正确';
                break;
        }
        if($return instanceof IImage) {
            return $return ;
        } else {
            echo '出错了';
            exit();
        }
    }

}
$image = ImageFactory::factory('path/my.png');
var_dump($image->getWidth());
echo '<br>';
print_r($image->getheight());
echo '<br>';
print_r($image->getData());