Server will comply with Upgrade header and change to different protocol. (New in HTTP 1.1)

Everything's fine; document follows for GET and POST requests. This is the default for servlets; if you don't use setStatus, you'll get this.

Server created a document; the Location header indicates its URL.

No new document; browser should continue to display previous document. This is a useful if the user periodically reloads a page and you can determine that the previous page is already up to date. However, this does not work for pages that are automatically reloaded via the Refresh response header or the equivalent <META HTTP-EQUIV="Refresh" ...> header, since returning this status code stops future reloading. JavaScript-based automatic reloading could still work in such a case, though.

No new document, but browser should reset document view. Used to force browser to clear CGI form fields. (New in HTTP 1.1)

Client sent a partial request with a Range header, and server has fulfilled it. (New in HTTP 1.1)

Document requested can be found several places; they'll be listed in the returned document. If server has a preferred choice, it should be listed in the Location response header.

Requested document is elsewhere, and the URL for it is given in the Location response header. Browsers should automatically follow the link to the new URL.

Similar to 301, except that the new URL should be interpreted as a temporary replacement, not a permanent one. Note: the message was "Moved Temporarily" in HTTP 1.0, and the constant in HttpServletResponse is SC_MOVED_TEMPORARILY, not SC_FOUND.Very useful header, since browsers automatically follow the link to the new URL. This status code is so useful that there is a special method for it, sendRedirect. Using response.sendRedirect(url) has a couple of advantages over doing response.setStatus(response.SC_MOVED_TEMPORARILY) and response.setHeader("Location", url). First, it is easier. Second, with sendRedirect, the servlet automatically builds a page containing the link (to show to older browsers that don't automatically follow redirects). Finally, sendRedirect can handle relative URLs, automatically translating them to absolute ones.

Note that this status code is sometimes used interchangeably with 301. some servers will send 301 and others will send 302.

Technically, browsers are only supposed to automatically follow the redirection if the original request was GET. See the 307 header for details.

Like 301/302, except that if the original request was POST, the redirected document (given in the Location header) should be retrieved via GET. (New in HTTP 1.1)

Client has a cached document and performed a conditional request (usually by supplying an If-Modified-Since header indicating that it only wants documents newer than a specified date). Server wants to tell client that the old, cached document should still be used.

Requested document should be retrieved via proxy listed in Location header. (New in HTTP 1.1)

This is identical to 302 ("Found" or "Temporarily Moved"). It was added to HTTP 1.1 since many browsers erroneously followed the redirection on a 302 response even if the original message was a POST, even though it really ought to have followed the redirection of a POST request only on a 303 response. This response is intended to be unambigously clear: follow redirected GET and POST requests in the case of 303 responses, only follow the redirection for GET requests in the case of 307 responses. Note: for some reason there is no constant in HttpServletResponse corresponding to this status code. (New in HTTP 1.1)

Client tried to access password-protected page without proper authorization. Response should include a WWW-Authenticate header that the browser would use to pop up a username/password dialog box, which then comes back via the Authorization header.

Resource is not available, regardless of authorization. Often the result of bad file or directory permissions on the server.

No resource could be found at that address. This is the standard "no such page" response. This is such a common and useful response that there is a special method for it in HttpServletResponse: sendError(message). The advantage of sendError over setStatus is that, with sendError, the server automatically generates an error page showing the error message.

Resource indicated generates a MIME type incompatible with that specified by the client via its Accept header. (New in HTTP 1.1)

Usually associated with PUT requests; used for situations such as trying to upload an incorrect version of a file. (New in HTTP 1.1)

Document is gone; no forwarding address known. Differs from 404 in that the document is is known to be permanently gone in this case, not just unavailable for unknown reasons as with 404. (New in HTTP 1.1)

Server cannot process request unless client sends a Content-Length header. (New in HTTP 1.1)

Some precondition specified in the request headers was false. (New in HTTP 1.1)

The requested document is bigger than the server wants to handle now. If the server thinks it can handle it later, it should include a Retry-After header. (New in HTTP 1.1)

Value in the Expect request header could not be met. (New in HTTP 1.1)

Generic "server is confused" message. It is often the result of CGI programs or (heaven forbid!) servlets that crash or return improperly formatted headers.

Server doesn't support functionality to fulfill request. Used, for example, when client issues command like PUT that server doesn't support.

Used by servers that act as proxies or gateways; indicates that initial server got a bad response from the remote server.

Server cannot respond due to maintenance or overloading. For example, a servlet might return this header if some thread or database connection pool is currently full. Server can supply a Retry-After header.

Used by servers that act as proxies or gateways; indicates that initial server didn't get a response from the remote server in time. (New in HTTP 1.1)

Server doesn't support version of HTTP indicated in request line. (New in HTTP 1.1)