src/thinkextend/Transform.php
public static function decode($content, $type, $assoc = true, array $config = [])
    {
        self::init($type);
        return self::$handler[$type]->decode($content, $assoc, $config);
    }
public static function decode($content, $type, $assoc = true, array $config = [])
    {
        self::init($type);
        return self::$handler[$type]->decode($content, $assoc, $config);
    }
解码数据
@param  string  $content 要解码的数据
@param  string  $type    数据类型
@param  boolean $assoc   是否返回数组
@param  array   $config  XML配置参数，JSON格式解码无此参数
@return mixed            解码后的数据