psr7-middlewares:PSR-7 HTTP消息对象的中间件

不再维护 而是创建可调用的中间件。 签名： function ( RequestInterface $ request , ResponseInterface $ response , callable $ next ) { // Do something with the request before passing it on. . . . // Pass on to next middleware. $ response = $ next ( $ request , $ response ); // Do something with the response after the next middleware has been called. . . . // Return ultimate response object.