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）

 1 unit Unit2;
 2 
 3 interface
 4 
 5   uses Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics, Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls,
 6     DBXJSON, DBXJSONReflect;
 7 
 8   type
 9     TPerson = class(TObject)
10     public
11       Name: String;
12       Password: String;
13       Age: Integer;
14     end;
15 
16     TForm2 = class(TForm)
17       Memo1: TMemo;
18       procedure FormCreate(Sender: TObject);
19     private
20       function ObjectToJSON(AData: TObject): TJSONValue;
21       function JSONToObject(AJSONValue: TJSONValue): TObject; 
22     public                                                    
23     end;
24 
25   var
26     Form2: TForm2;
27 
28 implementation
29 
30   {$R *.dfm}
31 
32   function TForm2.JSONToObject(AJSONValue: TJSONValue): TObject;
33   var
34     lUnMarshal: TJSONUnMarshal;
35   begin
36     lUnMarshal := TJSONUnMarshal.Create();
37     try
38       Result := lUnMarshal.Unmarshal(AJSONValue);
39     finally
40       FreeAndNil(lUnMarshal);
41     end;
42   end;
43 
44   function TForm2.ObjectToJSON(AData: TObject): TJSONValue;
45   var
46     lMarshal: TJSONMarshal;
47   begin
48     lMarshal := TJSONMarshal.Create();
49     try
50       Result := lMarshal.Marshal(AData);
51     finally
52       FreeAndNil(lMarshal);
53     end;
54   end;
55 
56   procedure TForm2.FormCreate(Sender: TObject);
57   var
58     lPerson: TPerson;
59     lJSONValue: TJSONValue;
60   const
61     lJSONString: String = '{"type":"Unit2.TPerson","id":1,"fields":{"Name":"Hezihang","Password":"123","Age":23}}';
62   begin
63     Memo1.Lines.Clear;
64     /// Object Convert to JSON
65     Memo1.Lines.Add('Object to JSON String');
66     Memo1.Lines.Add('--------------------------------------');
67     Memo1.Lines.Add('');
68     lPerson       := TPerson.Create;
69     lPerson.Name    := 'Hezihang';
70     lPerson.Password := '123';
71     lPerson.Age   := 23;
72     lJSONValue       := ObjectToJSON(lPerson);
73     FreeAndNil(lPerson);
74     Memo1.Lines.Add(lJSONValue.ToString);
75     lJSONValue.Free;
76     Memo1.Lines.Add('');
77     Memo1.Lines.Add('--------------------------------------');
78     /// JSON Convert to Object
79     Memo1.Lines.Add('');
80     Memo1.Lines.Add('JSON String'' To a Class Instance''');
81     Memo1.Lines.Add('--------------------------------------');
82     Memo1.Lines.Add('');
83     lJSONValue := TJSONObject.ParseJSONValue(lJSONString);
84     lPerson := JSONToObject(lJSONValue) as TPerson;
85     lJSONValue.Free;
86     Memo1.Lines.Add('Name: ' + lPerson.Name);
87     Memo1.Lines.Add('Password: ' + lPerson.Password);
88     Memo1.Lines.Add('Age: ' + IntToStr(lPerson.Age));
89     lPerson.Free;
90     Memo1.Lines.Add('');
91     Memo1.Lines.Add('--------------------------------------');
92   end;
93 
94 end.