Delphi 10 Seattle plus 新特性——System.JSON.Builders

  {
    全能中间件 —— 简单、高效、稳定、安全的三层中间件

    1.支持 多账套多数据库，包括SQLite, MySQL, SQL Server, Oracle, PostgreSQL, DB2, SQL Anywhere,Firebird等多种数据库。
    2.支持 快速开发，封装了 TRFConnection 和 TRFDataSet 控件供客户端使用，传统两层应用轻松升级为三层应用。
    3.支持 数据压缩、加密传输，效率和安全有保障。
    4.支持 数据连接池，提高并发响应速度。
    5.支持 客户端执行SQL语句，存储过程，亦可以把逻辑SQL放在中间层，控制权由您一手掌握。
    6.支持 Delta更新，比传统的拼接SQL更新方式效率高，兼容性更好。
    7.支持 SQL 参数化查询、 分页查询。
    8.支持 多表事务更新，会保证数据的一致性。
    9.支持 多表联合查询更新其中一个表。
    10.支持 多平台开发（Windows/Android/iOS/OS X)，各平台使用方法一致。
    11.支持 7x24小时长时间稳定运行，已经过多个正式项目长时间考验。

    Copyright @2014-2017 by QQ:64445322
    All rights reserved.

    QQ群：339616649
  }
 unit Unit1;

 interface

 uses
   Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
   Vcl.Controls, Vcl.Forms, Vcl.Dialogs, System.JSON.Writers, System.JSON.Types, System.JSON.Builders,
   System.JSON.Readers, Vcl.StdCtrls;

 type
   TForm1 = class(TForm)
     btnBuilder: TButton;
     Memo1: TMemo;
     btnReader: TButton;
     Memo2: TMemo;
     procedure FormCreate(Sender: TObject);
     procedure btnBuilderClick(Sender: TObject);
     procedure btnReaderClick(Sender: TObject);
   private
     { Private declarations }
   public
     { Public declarations }
   end;
   //http://docwiki.embarcadero.com/RADStudio/Tokyo/en/JSON#JSON_Frameworks
   TJSONBuilder = class(TJSONObjectBuilder)
   private
     FJsonWriter: TJsonTextWriter;
     FStringWriter: TStringWriter;
     FStringBuilder: TStringBuilder;
   strict private
     class var
       FJsonBuilder: TJSONBuilder;

     class destructor Destroy;
   public
     constructor Create(const AFormatting: TJsonFormatting = TJsonFormatting.None);
     destructor Destroy; override;

     function ToJSON: string;

     class function NewBuilder(const AFormatting: TJsonFormatting = TJsonFormatting.None): TJSONBuilder; static;
   end;

   TJsonObjectReader  = class (TJsonTextReader)
   private
     FStringReader : TStringReader;
   strict private
     class var
       FJsonObjectReader: TJsonObjectReader;
     class destructor Destroy;
   public
     constructor Create(const AJson: string);
     destructor Destroy; override;

    class function NewReader(const AJson:string): TJsonObjectReader; static;
   end;

 var
   Form1: TForm1;

 implementation

 {$R *.dfm}

 procedure TForm1.btnBuilderClick(Sender: TObject);
 var
   Builder: TJSONBuilder;
 begin
   Builder := TJSONBuilder.NewBuilder(TJsonFormatting.Indented);
   Builder
     .BeginObject
       .BeginArray('Transaction')
         .BeginObject.Add('id', )
           .Add('firstName', 'John')
           .Add('lastName', 'Doe')
           .Add('price', 2.1)
           .AddNull('parent_id')
           .Add('validated', True)
         .EndObject
         .BeginObject
           .Add('id', )
           .Add('firstName', 'Anna')
           .Add('lastName', 'Smith')
           .Add('price', 4.5)
           .AddNull('parent_id')
           .Add('validated', False)
         .EndObject
         .BeginObject
           .Add('id', )
           .Add('firstName', 'Peter')
           .Add('lastName', 'Jones')
           .Add('price', 3.6)
           .AddNull('parent_id')
           .Add('validated', True)
         .EndObject
       .EndArray
     .EndObject;

   Memo1.Text := Builder.ToJSON;

 end;

 procedure TForm1.btnReaderClick(Sender: TObject);
 var
   Reader:TJsonObjectReader;
 begin
   Memo2.Clear;
   Reader:=TJsonObjectReader.NewReader(Memo1.Text);

   while Reader.Read do
     case Reader.TokenType of
       TJsonToken.PropertyName:
       Memo2.Lines.Add(Reader.Value.AsString);
       TJsonToken.String:
       Memo2.Lines[Memo2.Lines.Count-] := Memo2.Lines[Memo2.Lines.Count-] + ': ' +Reader.Value.AsString;
     end;
 end;

 procedure TForm1.FormCreate(Sender: TObject);
 begin
   ReportMemoryLeaksOnShutdown := True;
 end;

 { TJSONBuilder }

 constructor TJSONBuilder.Create(const AFormatting: TJsonFormatting);
 begin
   FJsonBuilder := nil;
   FStringBuilder := TStringBuilder.Create;
   FStringWriter := TStringWriter.Create(FStringBuilder);
   FJsonWriter := TJsonTextWriter.Create(FStringWriter);
   FJsonWriter.Formatting := AFormatting;
   inherited Create(FJsonWriter);
 end;

 destructor TJSONBuilder.Destroy;
 begin
   FreeAndNil(FJsonWriter);
   FreeAndNil(FStringWriter);
   FreeAndNil(FStringBuilder);
   inherited;
 end;

 class destructor TJSONBuilder.Destroy;
 begin
   FreeAndNil(FJsonBuilder);
 end;

 class function TJSONBuilder.NewBuilder(const AFormatting: TJsonFormatting): TJSONBuilder;
 begin
   if FJsonBuilder <> nil then
     FreeAndNil(FJsonBuilder);

   FJsonBuilder := TJSONBuilder.Create(AFormatting);

   Result := FJsonBuilder;
 end;

 function TJSONBuilder.ToJSON: string;
 begin
   Result := FStringBuilder.ToString;
 end;

 { TJsonObjectReader }

 constructor TJsonObjectReader.Create(const AJson: string);
 begin
   FStringReader:= TStringReader.Create(AJson);
   inherited Create(FStringReader) ;
 end;

 class destructor TJsonObjectReader.Destroy;
 begin
   FreeAndNil(FJsonObjectReader);
 end;

 destructor TJsonObjectReader.Destroy;
 begin
   FreeAndNil(FStringReader);
   inherited;
 end;

 class function TJsonObjectReader.NewReader(const AJson:string): TJsonObjectReader;
 begin
    if FJsonObjectReader <> nil then
     FreeAndNil(FJsonObjectReader);

   FJsonObjectReader := TJsonObjectReader.Create(AJson);

   Result := FJsonObjectReader;
 end;

 end.

运行效果如图：