[转载]更灵活,更易维护的WebHandler之通用webHandler编码方案(2)

/* *
 * name     : ExecuteHandler.cs 
 * author   : newmin
 * date     : 09/29 2010
 * note     : 用来处理请求,请求的URI参数如:Exc.ashx?cmd=IP,GetIP,127.0.0.1
 * 
 * 要执行操作的类必需要程序集名称命名空间下:
 * 如要执行AtNet.Security下的User类,则User类的命名空间为:HuiShi.Security.User
 * 调用方式**.ashx?cmd=User,GetScore,newmin
 * 
 * */
namespace AtNet.Web
{
    using System;
    using System.Web;
    using System.Reflection;
    using System.Collections.Generic;

    public abstract class ExecuteHandler : IHttpHandler
    {
        //绑定类型用于获取程序集,只能在子类的静态构造函数中赋值
        protected static Type _type;
        #region IHttpHandler 成员
        public bool IsReusable{ get; set; }
        
        public void ProcessRequest(HttpContext context)
        {
            string cmd=context.Request["cmd"].Replace("+"," ");         //将空格做为+号替换

            string[] args = cmd.Split(',');
            if (args.Length > 2)
            {
                //获取执行当前代码的程序集并创建实例
               Assembly ass = Assembly.GetAssembly(_type);
                object obj = ass.CreateInstance(_type.Namespace+"."+args[0], true);

                //获取实例类型
                Type type=obj.GetType();

                //未添加WebExecuteAttribute特性的类将不被执行
                object[] attrs= type.GetCustomAttributes(typeof(WebExecuteAttribute), false);
                WebExecuteAttribute attr =attrs.Length>0?attrs[0] as WebExecuteAttribute:null;
                if (attr == null) { context.Response.Write("此模块不允许被执行!"); return; }

                //获取方法并执行
                MethodInfo method =type.GetMethod(args[1],BindingFlags.Instance|BindingFlags.Public|BindingFlags.IgnoreCase);
                object returnObj=method.GetParameters() != null?method.Invoke(obj,cmd.Substring(args[0].Length + args[1].Length + 2).Split(','))
                        :method.Invoke(obj, null);

                //如国返回String类型或值类型则输出到页面
                if (method.ReturnType == typeof(string) ||obj is ValueType)
                    context.Response.Write(returnObj.ToString());
            }
        }

        #endregion
    }
}

namespace AtNet.Web.Tools
{
    using System;
    using System.Reflection;

    public class WebHandler:AtNet.Web.ExecuteHandler
    {
        static WebHandler()
        {
           _type = typeof(WebHandler);
       }
    }
}