如何通过反射添加BackgroundWorker RunWorkerCompleted事件？

Question

通常我会说：

bgwExportGrid.RunWorkerCompleted += ReportManager.RunWorkerCompleted;

ReportManager类是一个静态类，其中包含我要使用的事件处理程序。

public static class ReportManager
{
        public static void RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
        {
        ...
        }
}

现在，我已经创建了一个BackgroundWorker，并希望按照ReportManager中的定义附加RunWorkerCompleted事件。但是，不能引用ReportManager，否则会发生循环引用，因此需要反射。

任何帮助都将不胜感激。

我已经看过以下内容，但还没有走得太远：

        Assembly assem = Utils.GetAssembly("WinUI.Reporting.Common.dll");
        Type reportManagerType = assem.GetModule("WinUI.Reporting.Common.dll").GetType("WinUI.Reporting.Common.ReportManager");
        EventInfo evWorkerCompleted = reportManagerType.GetEvent("RunWorkerCompleted");
        Type tDelegate = evWorkerCompleted.EventHandlerType;

Answer 1

我认为，如果您将接口从ReportManager缩减为两个程序集都可以引用的接口，那么将来您的代码将更容易维护。但是，如果这对你来说不是一个选择，我认为你正在尝试实现这样的事情：

namespace WindowsFormsApplication1
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
            AttachEventHandler(backgroundWorker1,
                  Type.GetType("WindowsFormsApplication1.EventHandlers"),
                  "RunWorkerCompleted");
            backgroundWorker1.RunWorkerAsync();
        }

        private void AttachEventHandler(BackgroundWorker bgw, Type targetType,
            string eventHandlerMethodName)
        {
            object targetInstance = Activator.CreateInstance(targetType);
            bgw.RunWorkerCompleted += 
                (RunWorkerCompletedEventHandler)Delegate.CreateDelegate(
                    typeof(RunWorkerCompletedEventHandler), 
                    targetInstance, eventHandlerMethodName);
        }

    }

    public class EventHandlers
    {
        public void RunWorkerCompleted(object sender, 
            System.ComponentModel.RunWorkerCompletedEventArgs e)
        {
            // do something 
        }
    }
}

请注意，Form1和EventHandlers类之间没有“硬”引用，因此可以是驻留在任何其他程序集中的任何其他类；事件处理程序是根据类型的名称和方法的名称创建和附加的(当然，它们必须具有正确的签名)。

Answer 2

更新答案：

Assembly assem = Utils.GetAssembly("WinUI.Reporting.Common.dll");

Type reportManagerType = assem.GetModule("WinUI.Reporting.Common.dll").GetType("WinUI.Reporting.Common.ReportManager");

// obtain the method info
MethodInfo mi = reportManagerType.GetMethod("RunWorkerCompleted", 
                                            BindingFlags.Static | BindingFlags.Public);

// create a delegate that we can further register with the event
Delegate handler = Delegate.CreateDelegate(reportManagerType , mi);

// get the event info from the export grid object
EventInfo evWorkerCompleted = bgwExportGrid.GetType().GetEvent("RunWorkerCompleted");

// invoke the event
evWorkerCompleted.AddEventHandler(bgwExportGrid, handler);

Answer 3

设法让它工作起来了。ReportManager是一个静态类，因此不需要使用Activator.CreateInstance。

        Assembly assem = Utils.GetAssembly("WinUI.Reporting.Common.dll");
        Type reportManagerType = assem.GetModule("WinUI.Reporting.Common.dll").GetType("WinUI.Reporting.Common.ReportManager");
        bgwExportGrid.RunWorkerCompleted += (RunWorkerCompletedEventHandler)Delegate.CreateDelegate(typeof(RunWorkerCompletedEventHandler), reportManagerType, "RunWorkerCompleted");