Search order of HttpRequest indexer

问题

If you do a simple index into Request's items via Request[key], it looks in 4 locations. What's the order? Someone makes a guess on that page at "Cookies, ServerVariables, Form and QueryString". Does anyone know for sure? Documentation would be a bonus :)

回答1:

public string this[string key] { get; }

Declaring Type: System.Web.HttpRequest Assembly: System.Web, Version=2.0.0.0

public string this[string key]
{
    get
    {
        string str = this.QueryString[key];
        if (str != null)
        {
            return str;
        }
        str = this.Form[key];
        if (str != null)
        {
            return str;
        }
        HttpCookie cookie = this.Cookies[key];
        if (cookie != null)
        {
            return cookie.Value;
        }
        str = this.ServerVariables[key];
        if (str != null)
        {
            return str;
        }
        return null;
    }
}

回答2:

Just use Reflector and you can see it for yourself. The order is QueryString, Form, Cookies, then ServerVariables.

回答3:

This is from an ASP site, but it still applies to ASP.NET:

All request object variables can be accessed directly by calling Request(variable) without the collection name. In this case, the Web server searches the collections in the following order:

1. QueryString
2. Form
3. Cookies
4. ClientCertificate
5. ServerVariables

来源：https://stackoverflow.com/questions/1632969/search-order-of-httprequest-indexer