在《Rails Way》103 页中有这样一段深入讲解 redirect_to 的。英语比较差，不能理解这段的意思，请问一下大义是什么？ Sebastian says . . . Which redirect is the right one? When you use Rails’s redirect_to method, you tell the user agent (i.e., the browser) to perform a new request for a different URL. That response can mean different things, and it’s why modern HTTP has four different status codes for redirection.The old HTTP 1.0 had two codes: 301 aka Moved Permanently and 302 aka Moved Temporarily. A permanent redirect meant that the user agent should forget about the old URL and use the new one from now on, updating any references it might have kept (i.e., a bookmark or in the case of Google, its search databases). A temporary redirect was a one-time only affair. The original URL was still valid, but for this particular request the user agent should fetch a new resource from the redirection URL. But there was a problem: If the original request had been a POST, what method should be used for the redirected request? For permanent redirects it was safe to assume the new request should be a GET, since that was the case in all usage scenarios. But temporary redirects were used both for redirecting to a view of a resource that had just been modified in the original POST request (which happens to be the most common usage pattern), and also for redirecting the entire original POST request to a new URL that would take care of it. HTTP 1.1 solved this problem with the introduction of two new status codes: 303 meaning See Other and 307 meaning Temporary Redirect. A 303 redirect would tell the user agent to perform a GET request, regardless of what the original verb was, whereas a 307 would always use the same method used for the original request. These days, most browsers handle 302 redirects the same way as 303, with a GET request, which is the argument used by the Rails Core team to keep using 302 in redirect_to. A 303 status would be the better alternative, because it leaves no room for interpretation (or confusion), but I guess nobody has found it annoying enough to push for a patch. If you ever need a 307 redirect, say, to continue processing a POST request in a different action, you can always accomplish your own custom redirect by assigning a path to response.header["Location"] and then rendering with render : status => 307. Redirection happens