Question

我正在尝试将代码添加到我没有源代码的第三方ASP.NET Web应用程序的application_start事件中。我是通过继承供应商的Global类来做到这一点的。这是代码（注意“new”关键字和对事件的基类版本的两次调用。这是因为基类方法不是抽象，虚拟或覆盖，我没有更改源代码）：

public class CustomGlobal : VendorNamespace.Global
{
    new protected void Application_Start(object sender, EventArgs e)
    {
        var logName = "SPPCustom";
        if (!System.Diagnostics.EventLog.SourceExists(logName))
        System.Diagnostics.EventLog.CreateEventSource(logName, "Application");
        var text = "Hello from Application Start!";
        System.Diagnostics.EventLog.WriteEntry(logName, "Application started!");
        File.WriteAllText(@"c:\ApplicationStart.txt", text);
        Debug.WriteLine(text);
        base.Application_Start(sender, e);
    }
    new protected void Session_Start(object sender, EventArgs e)
    {
        var logName = "SPPCustom";
        if (!System.Diagnostics.EventLog.SourceExists(logName))
            System.Diagnostics.EventLog.CreateEventSource(logName, "Application");
        System.Diagnostics.EventLog.WriteEntry(logName, "Session started!");
        base.Session_Start(sender, e);
    }
}

我在网站的global.asax文件中引用我的代码，如下所示：

<%@ Application Codebehind="Global.asax.cs" Inherits="MyNamespace.CustomGlobal" Language="C#" %>

Application_Start代码不会执行，但Session_Start代码会执行。我可以编写事件并从Session_Start写出文本文件，但是Application_Start，nadda。

有谁知道这里发生了什么？

编辑：

以下是执行Jan建议后的代码：公共类CustomGlobal：HttpApplication { private readonly Global _global; private readonly MethodInfo _appStartInfo; private readonly MethodInfo _sessionStartInfo;

    public CustomGlobal()
    {
        _global = new Global();
        _appStartInfo = typeof(Global).GetMethod("Application_Start", BindingFlags.Instance | BindingFlags.NonPublic);
        _sessionStartInfo = typeof(Global).GetMethod("Session_Start", BindingFlags.Instance | BindingFlags.NonPublic);
    }

    protected void Application_Start(object sender, EventArgs e)
    {

        var logName = "SPPCustom";
        if (!System.Diagnostics.EventLog.SourceExists(logName))
            System.Diagnostics.EventLog.CreateEventSource(logName, "Application");
        var text = "Hello Patient Portal from Application Start!";
        System.Diagnostics.EventLog.WriteEntry(logName, "Application started!");
        File.WriteAllText(@"c:\PatientPortalApplicationStart.txt", text);
        Debug.WriteLine(text);
        //_sxaGlobal.ApplicationStart(sender, e);
        _appStartInfo.Invoke(_global, new[] {sender, e});
    }
}

现在它抛出以下错误：

[NullReferenceException: Object reference not set to an instance of an object.]

Global.Application_Start（Object sender，EventArgs e）+28

[TargetInvocationException：调用目标抛出了异常。] System.RuntimeMethodHandle._InvokeMethodFast（IRuntimeMethodInfo方法，Object target，Object []参数，SignatureStruct＆amp; sig，MethodAttributes methodAttributes，RuntimeType typeOwner）+0 System.RuntimeMethodHandle.InvokeMethodFast（IRuntimeMethodInfo方法，Object target，Object []参数，Signature sig，MethodAttributes methodAttributes，RuntimeType typeOwner）+72 System.Reflection.RuntimeMethodInfo.Invoke（Object obj，BindingFlags invokeAttr，Binder binder，Object [] parameters，CultureInfo culture，Boolean skipVisibilityChecks）+251 System.Reflection.RuntimeMethodInfo.Invoke（Object obj，BindingFlags invokeAttr，Binder binder，Object []参数，CultureInfo文化）+28 System.Reflection.MethodBase.Invoke（Object obj，Object []参数）+19 CustomGlobal.Application_Start（Object sender，EventArgs e）+231

[HttpException（0x80004005）：调用目标抛出了异常。] System.Web.HttpApplicationFactory.EnsureAppStartCalledForIntegratedMode（HttpContext context，HttpApplication app）+9239341 System.Web.HttpApplication.RegisterEventSubscriptionsWithIIS（IntPtr appContext，HttpContext context，MethodInfo [] handlers）+131 System.Web.HttpApplication.InitSpecial（HttpApplicationState状态，MethodInfo []处理程序，IntPtr appContext，HttpContext上下文）+194 System.Web.HttpApplicationFactory.GetSpecialApplicationInstance（IntPtr appContext，HttpContext context）+339 System.Web.Hosting.PipelineRuntime.InitializeApplication（IntPtr appContext）+253

[HttpException（0x80004005）：调用目标抛出了异常。] System.Web.HttpRuntime.FirstRequestInit（HttpContext context）+9157968 System.Web.HttpRuntime.EnsureFirstRequestInit（HttpContext context）+97 System.Web.HttpRuntime.ProcessRequestNotificationPrivate（IIS7WorkerRequest wr，HttpContext context）+256

Answer 1

它的继承问题。使用new关键字后，调用CustomGlobal.Application_Start()将执行您的代码，但调用((HttpApplication) CustomGlobal).Application_Start()将执行供应商的代码。

解决方案可能是私人会员的模式

public class CustomGlobal : HttpApplication
{
    private readonly VendorGlobal _global;
    private readonly MethodInfo _appStartInfo;

    public CustomGlobal()
    {
        _global = new VendorGlobal();
        _appStartInfo = typeof(VendorGlobal).GetMethod("Application_Start", BindingFlags.Instance | BindingFlags.NonPublic);
    }

    protected void Application_Start(object sender, EventArgs e)
    {
        _appStartInfo.Invoke(_global, new[] {sender, e});
        // your custom code
    }

从供应商的Global.asax继承Global.asax时，不会触发Application_Start

1 个答案: