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挂载非引用Assembly中的事件

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 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:

01 private void btnAttachEvent_Click(object sender, EventArgs e)
02 {
03     if(assembly == null || fireEventForm == null)
04     {
05         MessageBox.Show("Please click the first button to load  the fire event form.");
06         return;
07     }
08     Type fireFarEventFormType = fireEventForm.GetType();
09     farEventEventInfo = fireFarEventFormType.GetEvent("SomeEvent");
10
11     EventHandler tempHandler = new EventHandler (this.farEventHandler); // for dynamic method.
12     MethodInfo tempHandlerMethodInfo = tempHandler.Method;
13
14
15     DynamicMethod dynamicMethod = new DynamicMethod(
16         "BridgeMethodForAttachEvent", typeof(void),
17         new Type[] { typeof(object), assembly.GetType ("FireFarEvent.FarEventArgs") },
18         this.GetType());
19
20     ILGenerator il = dynamicMethod.GetILGenerator();
21
22     il.Emit(OpCodes.Nop);
23     il.Emit(OpCodes.Ldarg_0);
24     il.Emit(OpCodes.Ldarg_2);
25     il.Emit(OpCodes.Ldarg_1);
26     il.Emit(OpCodes.Call, tempHandlerMethodInfo);
27     il.Emit(OpCodes.Nop);
28     il.Emit(OpCodes.Ret);
29
30     dynamicMethod.DefineParameter(1, ParameterAttributes.In,  "object");
31     dynamicMethod.DefineParameter(2, ParameterAttributes.In, "e");
32
33     farEventDelegate = dynamicMethod.CreateDelegate (farEventEventInfo.EventHandlerType);
34     farEventEventInfo.AddEventHandler(fireEventForm,  farEventDelegate);
35 }

 

DetachFarEvent代码如下:

1 private void btnDetachEvent_Click(object sender, EventArgs e)
2 {
3     if (assembly == null || fireEventForm == null ||  farEventEventInfo == null)
4     {
5         MessageBox.Show("Please click the first button to load  the fire event form.");
6         return;
7     }
8     farEventEventInfo.RemoveEventHandler(fireEventForm,  farEventDelegate);
9 }