IHttpHandler GetHandler( HttpContext context, string requestType, string url, string path )
下面是在实现 IHttpHandlerFactory 的类中 GetHandler 函数中得到的值（Web.Config 中已经在 HttpHandlers 设置中，将 path=* 映射到了这个HttpHandlerFactory 上：
访问地址：http://localhost/myweb/
path: d:\vhosts\myweb\
url: /myweb/
context.Request.Path: /myweb/
访问地址：http://localhost/myweb/a
path: d:\vhosts\myweb\a
url: /myweb/a
context.Request.Path: /myweb/a
访问地址：http://localhost/myweb/a/
path: d:\vhosts\myweb\a
url: /myweb/a/
context.Request.Path: /myweb/a/
访问地址：http://localhost/myweb/a/
path: d:\vhosts\myweb\a\
url: /myweb/a/
context.Request.Path: /myweb/a/
访问地址：http://localhost/myweb/a.aspx
path: d:\vhosts\myweb\a.aspx
url: /myweb/a.aspx
context.Request.Path: /myweb/a.aspx
访问地址：http://localhost/myweb/a.aspx?b=c
path: d:\vhosts\myweb\a.aspx
url: /myweb/a.aspx
context.Request.Path: /myweb/a.aspx
访问地址：http://localhost/myweb/a.aspx/b
path: d:\vhosts\myweb\a.aspx
url: /myweb/a.aspx
context.Request.Path: /myweb/a.aspx/b
访问地址：http://localhost/myweb/a.aspx/b.aspx/c.aspx
path: d:\vhosts\myweb\a.aspx
url: /myweb/a.aspx
context.Request.Path: /myweb/a.aspx/b.aspx/c.aspx