JSON与Delphi Object的互换

Delphi自从增强了RTTI后，语言的可灵活性多大增强，Delphi的dbExpress中提供了DBXJSON，和DBXJSONReflect两个单元，可提供JSON序列化

下面的例子是实现Delphi实体对象转换为JSON字符串，以及JSON字符串转换为Delphi 实体对象的示例：（在Delphi XE3测试通过）

 unit Unit2;

 interface

   uses Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics, Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls,
     DBXJSON, DBXJSONReflect;

   type
     TPerson = class(TObject)
     public
       Name: String;
       Password: String;
       Age: Integer;
     end;

     TForm2 = class(TForm)
       Memo1: TMemo;
       procedure FormCreate(Sender: TObject);
     private
       function ObjectToJSON(AData: TObject): TJSONValue;
       function JSONToObject(AJSONValue: TJSONValue): TObject;
     public
     end;

   var
     Form2: TForm2;

 implementation

   {$R *.dfm}

   function TForm2.JSONToObject(AJSONValue: TJSONValue): TObject;
   var
     lUnMarshal: TJSONUnMarshal;
   begin
     lUnMarshal := TJSONUnMarshal.Create();
     try
       Result := lUnMarshal.Unmarshal(AJSONValue);
     finally
       FreeAndNil(lUnMarshal);
     end;
   end;

   function TForm2.ObjectToJSON(AData: TObject): TJSONValue;
   var
     lMarshal: TJSONMarshal;
   begin
     lMarshal := TJSONMarshal.Create();
     try
       Result := lMarshal.Marshal(AData);
     finally
       FreeAndNil(lMarshal);
     end;
   end;

   procedure TForm2.FormCreate(Sender: TObject);
   var
     lPerson: TPerson;
     lJSONValue: TJSONValue;
   const
     lJSONString: String = '{"type":"Unit2.TPerson","id":1,"fields":{"Name":"Hezihang","Password":"123","Age":23}}';
   begin
     Memo1.Lines.Clear;
     /// Object Convert to JSON
     Memo1.Lines.Add('Object to JSON String');
     Memo1.Lines.Add('--------------------------------------');
     Memo1.Lines.Add('');
     lPerson       := TPerson.Create;
     lPerson.Name    := 'Hezihang';
     lPerson.Password := '';
     lPerson.Age   := ;
     lJSONValue       := ObjectToJSON(lPerson);
     FreeAndNil(lPerson);
     Memo1.Lines.Add(lJSONValue.ToString);
     lJSONValue.Free;
     Memo1.Lines.Add('');
     Memo1.Lines.Add('--------------------------------------');
     /// JSON Convert to Object
     Memo1.Lines.Add('');
     Memo1.Lines.Add('JSON String'' To a Class Instance''');
     Memo1.Lines.Add('--------------------------------------');
     Memo1.Lines.Add('');
     lJSONValue := TJSONObject.ParseJSONValue(lJSONString);
     lPerson := JSONToObject(lJSONValue) as TPerson;
     lJSONValue.Free;
     Memo1.Lines.Add('Name: ' + lPerson.Name);
     Memo1.Lines.Add('Password: ' + lPerson.Password);
     Memo1.Lines.Add('Age: ' + IntToStr(lPerson.Age));
     lPerson.Free;
     Memo1.Lines.Add('');
     Memo1.Lines.Add('--------------------------------------');
   end;

 end.