PHP 获取图片的类型

if ( ! function_exists( 'exif_imagetype' ) ) {
    function exif_imagetype ( $filename ) {
        if ( ( list($width, $height, $type, $attr) = getimagesize( $filename ) ) !== false ) {
            return $type;
        }
    return false;
    }
}

# libexif can also be used to parse image info out of id3 tags:

exif_read_data("mp3_with_2.4ID3TAGS, '', true, false);