ashx的使用

1、必须实现IHttpHandler（如果需要使用Session，则还需要实现IRequiresSessionState接口，这只是个标记接口，实际上没有方法），完成方法public void ProcessRequest(HttpContext context)。例如提供一个文件下载：

        public void ProcessRequest(HttpContext context)
        {
            //context.Response.ContentType = ".*";
            //context.Response.Charset = "utf-8";

            //如果要直接打开则注释以下部分，或把"attachment"要改为“inline”
            string downName = "下载时的文件名.txt";
            context.Response.AddHeader("content-disposition",
                string.Format("attachment; filename={0}", context.Server.UrlEncode(downName)));

            //输出原文件
            string srcPath = context.Server.MapPath("~/readme.txt");
            context.Response.WriteFile(srcPath);
        }

2、在web.config中，加入以下代码：

   <httpHandlers>
      <remove verb="*" path="*.asmx"/>
      <add verb="*" path="ashx/IHttpHandler1.ashx" type="TestJavascript.IHttpHandler1, TestJavascript" />
      <add verb="*" path="*.asmx" validate="false" type="System.Web.Script.Services.ScriptHandlerFactory, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/>
      <add verb="*" path="*_AppService.axd" validate="false" type="System.Web.Script.Services.ScriptHandlerFactory, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/>
      <add verb="GET,HEAD" path="ScriptResource.axd" type="System.Web.Handlers.ScriptResourceHandler, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" validate="false"/>
    </httpHandlers>

3、如果是IIS7，则Web.config中还需要加入：

  <system.webServer>
    <validation validateIntegratedModeConfiguration="false"/>
    <modules runAllManagedModulesForAllRequests="true"/>
    <handlers>
      <add verb="*" name="IHttpHandler1" path="ashx/IHttpHandler1.ashx" type="TestJavascript.IHttpHandler1, TestJavascript" />
    </handlers>
  </system.webServer>

4、如果是MVC，需要在Global.asax文件中忽略路由：

        public static void RegisterRoutes(RouteCollection routes)
        {
            routes.("{resource}.axd/{*pathInfo}");
            routes.IgnoreRoute("{folder}/{resource}.ashx/{*pathInfo}");

            routes.MapRoute(
                "Default", // Route name
                "{controller}/{action}/{id}", // URL with parameters
                new { controller = "Home", action = "Index", id = UrlParameter.Optional } // Parameter defaults
            );
        }

接下来，就可以使用：http://localhost/ashx/IHttpHandler1.ashx来访问了