Delphi下获取RTTI信息源代码

最新推荐文章于 2022-08-10 17:11:47 发布

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#delphi #integer #object #events #string #框架

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本文介绍如何使用 Delphi 的运行时类型信息 (RTTI) 来获取类的基本信息及属性详情，包括类名、类型、大小等，并通过示例展示了获取属性名称和类型的方法。

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procedure GetBaseClassInfo(AClass: TObject; AStrings: TStrings);
{ This method obtains some basic RTTI data from the given object and adds that
  information to the AStrings parameter. }
var
  ClassTypeInfo: PTypeInfo;
  ClassTypeData: PTypeData;
  EnumName: String;
begin
  ClassTypeInfo := AClass.ClassInfo;
  ClassTypeData := GetTypeData(ClassTypeInfo);
  with AStrings do
  begin
    Add(Format('Class Name:     %s', [ClassTypeInfo.Name]));
    EnumName := GetEnumName(TypeInfo(TTypeKind), Integer(ClassTypeInfo.Kind));
    Add(Format('Kind:           %s', [EnumName]));
    Add(Format('Size:           %d', [AClass.InstanceSize]));
    Add(Format('Defined in:     %s.pas', [ClassTypeData.UnitName]));
    Add(Format('Num Properties: %d',[ClassTypeData.PropCount]));
  end;
end;

procedure GetClassProperties(AClass: TObject; AStrings: TStrings);
{ This method retrieves the property names and types for the given object
  and adds that information to the AStrings parameter. }
var
  PropList: PPropList;
  ClassTypeInfo: PTypeInfo;
  ClassTypeData: PTypeData;
  i: integer;
  NumProps: Integer;
begin

  ClassTypeInfo := AClass.ClassInfo;
  ClassTypeData := GetTypeData(ClassTypeInfo);

  if ClassTypeData.PropCount <> 0 then
  begin
    // allocate the memory needed to hold the references to the TPropInfo
    // structures on the number of properties.
    GetMem(PropList, SizeOf(PPropInfo) * ClassTypeData.PropCount);
    try
      // fill PropList with the pointer references to the TPropInfo structures
      GetPropInfos(AClass.ClassInfo, PropList);
      for i := 0 to ClassTypeData.PropCount - 1 do
        // filter out properties that are events ( method pointer properties)
        if not (PropList[i]^.PropType^.Kind = tkMethod) then
          AStrings.Add(Format('%s: %s', [PropList[i]^.Name, PropList[i]^.PropType^.Name]));

      // Now get properties that are events (method pointer properties)
      NumProps := GetPropList(AClass.ClassInfo, [tkMethod], PropList);
      if NumProps <> 0 then begin
        AStrings.Add('');
        AStrings.Add('   EVENTS   ================ ');
        AStrings.Add('');
      end;
      // Fill the AStrings with the events.
      for i := 0 to NumProps - 1 do
          AStrings.Add(Format('%s: %s', [PropList[i]^.Name, PropList[i]^.PropType^.Name]));

    finally
      FreeMem(PropList, SizeOf(PPropInfo) * ClassTypeData.PropCount);
    end;
  end;

end;

运用Delphi 的 RTTI可以实现 Java 与 C# 下的反射机制，只是大家在Delphi 下做 RAD开发做多了，没有关注到这些关键的技术，接下来会写一个Delphi 下的OR Mapping框架，到时候会与大家分享。