挂载非引用Assembly中的事件

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