404是您***的选择.根据HTTP RFC， http://www.ietf.org/rfc/rfc2616.txt，"400错误请求"表示:

404 is your best response. According the HTTP RFC, http://www.ietf.org/rfc/rfc2616.txt, a 400 Bad Request means:

由于语法格式错误，服务器无法理解该请求.

The request could not be understood by the server due to malformed syntax.

其中404指出:

服务器未找到与请求URI匹配的任何内容.

The server has not found anything matching the Request-URI.

整个URI是您的资源标识符，而您没有找到该特定标识符的匹配资源.

The entire URI is your resource identifier, and you're not finding a matching resource for that particular identifier.