string fullpath = context.Server.MapPath("hello.htm");    //得到hello.htm的全路径

string content = System.IO.File.ReadAllText();        //读入文件内容

context.Response.Write(content);            //将hello.htm的内容打出来

string username = context.Request["UserName"];        //获得URL中UserName参数的值

if (string.IsNullOrEmpty(username))            //判断是否有值

{

    context.Response.Write("直接进入");

}else{

    context.Response.Write("提交进入");

}