函数放在common.php公共文件即可

function thumb($src = '', $width = 500, $height = 500, $type = 1, $replace = false) {
    $src = './'.$src;
    if(is_file($src) && file_exists($src)) {
        $ext = pathinfo($src, PATHINFO_EXTENSION);
        $name = basename($src, '.'.$ext);
        $dir = dirname($src);
        if(in_array($ext, array('gif','jpg','jpeg','bmp','png'))) {
            $name = $name.'_thumb_'.$width.'_'.$height.'.'.$ext;
            $file = $dir.'/'.$name;
            if(!file_exists($file) || $replace == TRUE) {
                $image = \think\Image::open($src);
                $image->thumb($width, $height, $type);
                $image->save($file);
            }
            $file=str_replace("\\","/",$file);
            $file = '/'.trim($file,'./');
            return $file;
        }
    }
    $src=str_replace("\\","/",$src);
    $src = '/'.trim($src,'./');
    return $src;
}