有两个 Assembly A,B 在A中声明了一个事件(某个类中的某个事件)， B没有引用这Assembly ，但是想挂A中的这个事件。当A中的某个逻辑fire这个Event时，B挂事件的地方要(B的handler)要做些事情。
FireFarEvent 是 Assembly A, MainForm 类公开一个 SomeEvent 事件， FireEvent button 会 Fire 这个 Event.
AttachFarEvent 是 Assembly B, AttachFarEventForm 中 btnAttachEvent_Click 会 hook FireFarEvent 中的 SomeEvent.
AttachFarEvent代码如下：
private void btnAttachEvent_Click(object sender, EventArgs e)
{
if(assembly == null || fireEventForm == null)
{
MessageBox.Show("Please click the first button to load the fire event form.");
return;
}
Type fireFarEventFormType = fireEventForm.GetType();
farEventEventInfo = fireFarEventFormType.GetEvent("SomeEvent");
EventHandler tempHandler = new EventHandler(this.farEventHandler); // for dynamic method.
MethodInfo tempHandlerMethodInfo = tempHandler.Method;
DynamicMethod dynamicMethod = new DynamicMethod(
"BridgeMethodForAttachEvent", typeof(void),
new Type[] { typeof(object), assembly.GetType("FireFarEvent.FarEventArgs") },
this.GetType());
ILGenerator il = dynamicMethod.GetILGenerator();
il.Emit(OpCodes.Nop);
il.Emit(OpCodes.Ldarg_0);
il.Emit(OpCodes.Ldarg_2);
il.Emit(OpCodes.Ldarg_1);
il.Emit(OpCodes.Call, tempHandlerMethodInfo);
il.Emit(OpCodes.Nop);
il.Emit(OpCodes.Ret);
dynamicMethod.DefineParameter(1, ParameterAttributes.In, "object");
dynamicMethod.DefineParameter(2, ParameterAttributes.In, "e");
farEventDelegate = dynamicMethod.CreateDelegate(farEventEventInfo.EventHandlerType);
farEventEventInfo.AddEventHandler(fireEventForm, farEventDelegate);
}
DetachFarEvent代码如下：
private void btnDetachEvent_Click(object sender, EventArgs e)
{
if (assembly == null || fireEventForm == null || farEventEventInfo == null)
{
MessageBox.Show("Please click the first button to load the fire event form.");
return;
}
farEventEventInfo.RemoveEventHandler(fireEventForm, farEventDelegate);
}
Demo下载：AttachFarEvent.rar
