在web.config中修改修改属性
1：<configSections><configSections>中加下面代码
<configSections>
<sectionGroup name="system.web.extensions" type="System.Web.Configuration.SystemWebExtensionsSectionGroup, System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35">
<sectionGroup name="scripting" type="System.Web.Configuration.ScriptingSectionGroup, System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35">
<section name="scriptResourceHandler" type="System.Web.Configuration.ScriptingScriptResourceHandlerSection, System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" requirePermission="false" allowDefinition="MachineToApplication"/>
<sectionGroup name="webServices" type="System.Web.Configuration.ScriptingWebServicesSectionGroup, System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35">
<section name="jsonSerialization" type="System.Web.Configuration.ScriptingJsonSerializationSection, System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" requirePermission="false" allowDefinition="Everywhere"/>
<section name="profileService" type="System.Web.Configuration.ScriptingProfileServiceSection, System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" requirePermission="false" allowDefinition="MachineToApplication"/>
<section name="authenticationService" type="System.Web.Configuration.ScriptingAuthenticationServiceSection, System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" requirePermission="false" allowDefinition="MachineToApplication"/>
</sectionGroup>
以前发过一个.NET上传文件的方法的，不过那个方法中对文件类型的判断只是对后缀名来进行判断的，这样假如我把一个txt文本文件的后缀名改为jpg了也可以上传，这样无意中就造成了安全问题。
刚刚从网上找了个方法，试验了一下，是能够辨认出正确的文件类型的，如下：
using System;
using System.Collections.Generic; ......
using System;
using System.Collections.Generic;
using System.Text;
using System.Web;
namespace pub.mo
{
public class request
{
private request() { }
/// <summary>
/// 获取session
/// </summary>
/// <param name="_session_name" ......
