关于Request.QueryString解决思路

关于Request.QueryString
例如地址栏:
http://localhost:19304/BalloonShopTest/Catalog.aspx?DepartmentID=1&CategoryID=1

string departmentId = Request.QueryString["DepartmentID"];
string categoryId = Request.QueryString["CategoryID"];

为什么categoryId是空的，取不到值1

------解决方案--------------------------------------------------------
aspx?DepartmentID=1&CategoryID=1 把&换成&试试


------解决方案--------------------------------------------------------
一般 我们地址栏上的是这样儿的
http://localhost:19304/BalloonShopTest/Catalog.aspx?DepartmentID=1&CategoryID=1


------解决方案--------------------------------------------------------
http://localhost:19304/BalloonShopTest/Catalog.aspx?DepartmentID=1&CategoryID=1

&换成& 
string departmentId = Request.QueryString["DepartmentID"];
string categoryId = Request.QueryString["CategoryID"];

------解决方案--------------------------------------------------------
aspx?DepartmentID=1&CategoryID=1
1楼正解
------解决方案--------------------------------------------------------

C# code

HtmlEncode： 将 Html 源文件中不允许出现的字符进行编码，通常是编码以下字符"<"、">"、"&" 等。HtmlDecode： 刚好跟 HtmlEncode 相关，解码出来原本的字符。
------解决方案--------------------------------------------------------
string str=String.Format("Catalog.aspx?DepartmentID={0}&CategoryID={1}", departmentID, categoryID);
str = str.Replace("&amp;","&");