Delphi判断某个类是否实现了某个接口
通过TObject.GetInterface可以获得对象的实例实现某个接口，前提条件是必须实例化对象后才能运行GetInterface
下面的方法可获取类是否实现了某个接口，并返回接口的偏移：
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function FindInterface(AClass: TClass; GUID:TGUID; var Offset:NativeInt):Boolean;var i : integer; InterfaceTable: PInterfaceTable; InterfaceEntry: PInterfaceEntry;begin while Assigned(AClass) do begin InterfaceTable := AClass.GetInterfaceTable; if Assigned(InterfaceTable) then begin for i := 0 to InterfaceTable.EntryCount-1 do begin InterfaceEntry := @InterfaceTable.Entries[i]; if InterfaceEntry.IID=GUID then begin Offset:=InterfaceEntry.IOffset; Exit(True); end; end; end; AClass := AClass.ClassParent; end;end; |
下面我们看下通过偏移量的快速获得对象的接口，以及通过接口快速获取对象：
快速获取对象的接口：
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type TSomeObject=class(TXXX, ISomeInterface) ...... end;var FItemObjectOffset:NativeInt;//获取偏移量FindInterface(TSomeObject, ISomeInterface, FItemObjectOffset)var P:TSomeObject; Intf:ISomeInterface;....................................//通过对象直接获取接口 PNativeInt(@Intf)^:=PNativeInt(@P)^+ FItemObjectOffset; Intf._AddRef; |
快速通过接口获取对象
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type TSomeObject=class(TXXX, ISomeInterface) ...... end;var FItemObjectOffset:NativeInt;//获取偏移量FindInterface(TSomeObject, ISomeInterface, FItemObjectOffset)var P:TSomeObject; Intf:ISomeInterface;....................................//通过接口获取对象 P:=TSomeObject(Pointer(PNativeInt(@Intf)^- FItemObjectOffset)); |
