哪个部分将“Content-Type”设置为“text/HTML”作为响应

Question

这里是一些 Laravel 的路线代码：

Route::get('a', function() {
    return 'hello';
});

调用此路由，Content-Type 标头值为text/HTML。

这种默认行为从何而来？是否设置：

• Nginx?
• PHP?
• Laravel?

Answer 1

Laravel 扩展了 Symphony 的请求/响应，但仍然与它们的默认行为密切相关。此特定功能基于 Symphony 的 Response::prepare 函数。

public function prepare(Request $request)
{
    //does a lot of things, would not go into detail
        // Content-type based on the Request
        if (!$headers->has('Content-Type')) {
            $format = $request->getRequestFormat();
            if (null !== $format && $mimeType = $request->getMimeType($format)) {
                $headers->set('Content-Type', $mimeType);
            }
        }
 //Does a lot more things
}

这是基于$request->getMimeType($format)函数，$format来自$request->getRequestFormat()

public function getRequestFormat($default = 'html')
{
    if (null === $this->format) {
        $this->format = $this->attributes->get('_format');
    }
    return null === $this->format ? $default : $this->format;
}

请注意，当没有明确设置请求格式时，默认值是“html”。如果您还没有明确设置它，它也只会被设置。

mime 类型基于在 https://github.com/symfony/http-foundation/blob/master/Request.php#L1844 初始化的查找

该框架确实超越了这个级别，并提供了替代响应类型，例如JsonResponse（当你做 response()->json() 时 laravel 使用什么）并且这个响应使用不同的默认值。

Answer 2

使用路由时，laravel 会设置 header 值。这是symfony/http-foundation/Response.php的摘录

public function __construct($content = '', $status = 200, $headers = array())
{
    $this->headers = new ResponseHeaderBag($headers);
    $this->setContent($content);
    $this->setStatusCode($status);
    $this->setProtocolVersion('1.0');

    /* RFC2616 - 14.18 says all Responses need to have a Date */
    if (!$this->headers->has('Date')) {
        $this->setDate(\DateTime::createFromFormat('U', time()));
    }
}

希望这会有所帮助！

Answer 3

laravel 会自动将字符串转换成完整的 HTTP 响应。

我在 symfony/http-foundation/response.php 中找到了这个方法。可能是此方法用于创建响应标头。

 public function prepare(Request $request)
 {
    $headers = $this->headers;

    if ($this->isInformational() || $this->isEmpty()) {
        $this->setContent(null);
        $headers->remove('Content-Type');
        $headers->remove('Content-Length');
    } else {
        // Content-type based on the Request
       if (!$headers->has('Content-Type')) {
            $format = $request->getRequestFormat();
            if (null !== $format && $mimeType = $request->getMimeType($format)) {
                $headers->set('Content-Type', $mimeType);
            }
        }

        // Fix Content-Type
        $charset = $this->charset ?: 'UTF-8';
        if (!$headers->has('Content-Type')) {
            $headers->set('Content-Type', 'text/html; charset='.$charset);
        } elseif (0 === stripos($headers->get('Content-Type'), 'text/') && false === stripos($headers->get('Content-Type'), 'charset')) {
            // add the charset
            $headers->set('Content-Type', $headers->get('Content-Type').'; charset='.$charset);
        }

        // Fix Content-Length
        if ($headers->has('Transfer-Encoding')) {
            $headers->remove('Content-Length');
        }

        if ($request->isMethod('HEAD')) {
            // cf. RFC2616 14.13
            $length = $headers->get('Content-Length');
            $this->setContent(null);
            if ($length) {
                $headers->set('Content-Length', $length);
            }
        }
    }

    // Fix protocol
    if ('HTTP/1.0' != $request->server->get('SERVER_PROTOCOL')) {
        $this->setProtocolVersion('1.1');
    }

    // Check if we need to send extra expire info headers
    if ('1.0' == $this->getProtocolVersion() && false !== strpos($this->headers->get('Cache-Control'), 'no-cache')) {
        $this->headers->set('pragma', 'no-cache');
        $this->headers->set('expires', -1);
    }

    $this->ensureIEOverSSLCompatibility($request);

    return $this;
}