PostSharp 应用小结

PostSharp 使用IL静态注入实现AOP，

下面例子对登录操作进行静态注入，使用Web application ,记录每次登录

PostSharp的使用方法很简单，将自定义的属性 LoggerTrace直接加在需要注册的方法上就可以（事件是特殊的方法）

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using PostSharpLogger;
namespace PostSharpWebForm.Account
{
    public partial class Login : Page
    {


        [LoggerTrace]
        protected void Page_Load(object sender, EventArgs e)
        {
            try
            {
                RegisterHyperLink.NavigateUrl = "Register";
                OpenAuthLogin.ReturnUrl = Request.QueryString["ReturnUrl"];

                var returnUrl = HttpUtility.UrlEncode(Request.QueryString["ReturnUrl"]);
                if (!String.IsNullOrEmpty(returnUrl))
                {
                    RegisterHyperLink.NavigateUrl += "?ReturnUrl=" + returnUrl;
                }
            }
            catch (Exception)
            {

                throw;
            }
            finally
            {
                Response.Write("Hi ^<>^");
            }
        }

        protected void Page_Load2(object sender, EventArgs e)
        {
            RegisterHyperLink.NavigateUrl = "Register";
            OpenAuthLogin.ReturnUrl = Request.QueryString["ReturnUrl"];

            var returnUrl = HttpUtility.UrlEncode(Request.QueryString["ReturnUrl"]);
            if (!String.IsNullOrEmpty(returnUrl))
            {
                RegisterHyperLink.NavigateUrl += "?ReturnUrl=" + returnUrl;
            }
        }
    }
}

下面是 创建的自定义属性，具体用法可以查看PostSharp的文档

using PostSharp.Aspects;
using System;

namespace PostSharpLogger
{
    [Serializable]
    public class LoggerTraceAttribute : OnMethodBoundaryAspect
    {
        public override void OnEntry(MethodExecutionArgs args)
        {
            WriteLog.Log(string.Format("Before Entering {0}.{1}.", args.Method.DeclaringType.FullName, args.Method.Name));
            args.ReturnValue = "I'm onEntry";
            
        }
        public override void OnSuccess(MethodExecutionArgs args)
        {
            WriteLog.Log(string.Format("Before Entering {0}.{1}.", args.Method.DeclaringType.FullName, args.Method.Name));
        }
        public override void OnExit(MethodExecutionArgs args)
        {
            WriteLog.Log(string.Format(" After Entering {0}.{1}.", args.Method.DeclaringType.FullName, args.Method.Name));
            args.ReturnValue = args.MethodExecutionTag;
            args.FlowBehavior = FlowBehavior.Return;
        }

        public override void OnException(MethodExecutionArgs args)
        {
            WriteLog.Log(string.Format("Error Entering {0}.{1}.", args.Method.DeclaringType.FullName, args.Method.Name));
        }
    }
}

编译Web application 之后，使用　　ILSpy查看 Web application的DLL

被注入的方法编译后变成：

using PostSharp.Aspects;
using PostSharp.Aspects.Internals;
using PostSharp.ImplementationDetails_c77a9d44;
using System;
using System.Reflection;
using System.Runtime.CompilerServices;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
namespace PostSharpWebForm.Account
{
	public class Login : Page
	{
		protected HyperLink RegisterHyperLink;
		protected OpenAuthProviders OpenAuthLogin;
		protected void Page_Load(object sender, EventArgs e)
		{
			MethodExecutionArgs methodExecutionArgs = new MethodExecutionArgs(this, new Arguments<object, EventArgs>
			{
				Arg0 = sender,
				Arg1 = e
			});
			MethodExecutionArgs arg_27_0 = methodExecutionArgs;
			MethodBase  = <>z__a_1._1;
			arg_27_0.Method = ;
			<>z__a_1.a0.OnEntry(methodExecutionArgs);
			if (methodExecutionArgs.FlowBehavior != FlowBehavior.Return)
			{
				try
				{
					try
					{
						this.RegisterHyperLink.NavigateUrl = "Register";
						this.OpenAuthLogin.ReturnUrl = base.Request.QueryString["ReturnUrl"];
						string returnUrl = HttpUtility.UrlEncode(base.Request.QueryString["ReturnUrl"]);
						if (!string.IsNullOrEmpty(returnUrl))
						{
							HyperLink expr_A4 = this.RegisterHyperLink;
							expr_A4.NavigateUrl = expr_A4.NavigateUrl + "?ReturnUrl=" + returnUrl;
						}
					}
					catch (Exception)
					{
						throw;
					}
					finally
					{
						base.Response.Write("Hi ^<>^");
					}
					<>z__a_1.a0.OnSuccess(methodExecutionArgs);
				}
				catch (Exception exception)
				{
					methodExecutionArgs.Exception = exception;
					<>z__a_1.a0.OnException(methodExecutionArgs);
					switch (methodExecutionArgs.FlowBehavior)
					{
					case FlowBehavior.Default:
					case FlowBehavior.RethrowException:
						IL_11E:
						throw;
					case FlowBehavior.Continue:
						methodExecutionArgs.Exception = null;
						return;
					case FlowBehavior.Return:
						methodExecutionArgs.Exception = null;
						return;
					case FlowBehavior.ThrowException:
						throw methodExecutionArgs.Exception;
					}
					goto IL_11E;
				}
				finally
				{
					<>z__a_1.a0.OnExit(methodExecutionArgs);
				}
			}
		}
		protected void Page_Load2(object sender, EventArgs e)
		{
			this.RegisterHyperLink.NavigateUrl = "Register";
			this.OpenAuthLogin.ReturnUrl = base.Request.QueryString["ReturnUrl"];
			string returnUrl = HttpUtility.UrlEncode(base.Request.QueryString["ReturnUrl"]);
			if (!string.IsNullOrEmpty(returnUrl))
			{
				HyperLink expr_5F = this.RegisterHyperLink;
				expr_5F.NavigateUrl = expr_5F.NavigateUrl + "?ReturnUrl=" + returnUrl;
			}
		}
		[CompilerGenerated]
		static Login()
		{
			<>z__a_1.Initialize();
		}
	}
}

　　原有的方法被加载一个try catch 中