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

Posted 2020-10-05 全能中间件

  1  {
  2    全能中间件 —— 简单、高效、稳定、安全的三层中间件
  3 
  4    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。
  5    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。
  6    3.支持 数据压缩、加密传输，效率和安全有保障。
  7    4.支持 数据连接池，提高并发响应速度。
  8    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。
  9    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。
 10    7.支持 SQL 参数化查询、 分页查询。
 11    8.支持 多表事务更新，会保证数据的一致性。
 12    9.支持 多表联合查询更新其中一个表。
 13    10.支持 多平台开发（Windows/android/ios/OS X)，各平台使用方法一致。
 14    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。
 15 
 16    Copyright @2014-2017 by QQ:64445322
 17    All rights reserved.
 18 
 19    QQ群：339616649
 20  }
 21 unit Unit1;
 22 
 23 interface
 24 
 25 uses
 26   Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
 27   Vcl.Controls, Vcl.Forms, Vcl.Dialogs, System.JSON.Writers, System.JSON.Types, System.JSON.Builders,
 28   System.JSON.Readers, Vcl.StdCtrls;
 29 
 30 type
 31   TForm1 = class(TForm)
 32     btnBuilder: TButton;
 33     Memo1: TMemo;
 34     btnReader: TButton;
 35     Memo2: TMemo;
 36     procedure FormCreate(Sender: TObject);
 37     procedure btnBuilderClick(Sender: TObject);
 38     procedure btnReaderClick(Sender: TObject);
 39   private
 40     { Private declarations }
 41   public
 42     { Public declarations }
 43   end;
 44   //http://docwiki.embarcadero.com/RADStudio/Tokyo/en/JSON#JSON_Frameworks
 45   TJSONBuilder = class(TJSONObjectBuilder)
 46   private
 47     FJsonWriter: TJsonTextWriter;
 48     FStringWriter: TStringWriter;
 49     FStringBuilder: TStringBuilder;
 50   strict private
 51     class var
 52       FJsonBuilder: TJSONBuilder;
 53 
 54     class destructor Destroy;
 55   public
 56     constructor Create(const AFormatting: TJsonFormatting = TJsonFormatting.None);
 57     destructor Destroy; override;
 58 
 59     function ToJSON: string;
 60 
 61     class function NewBuilder(const AFormatting: TJsonFormatting = TJsonFormatting.None): TJSONBuilder; static;
 62   end;
 63 
 64   TJsonObjectReader  = class (TJsonTextReader)
 65   private
 66     FStringReader : TStringReader;
 67   strict private
 68     class var
 69       FJsonObjectReader: TJsonObjectReader;
 70     class destructor Destroy;
 71   public
 72     constructor Create(const AJson: string);
 73     destructor Destroy; override;
 74 
 75    class function NewReader(const AJson:string): TJsonObjectReader; static;
 76   end;
 77 
 78 var
 79   Form1: TForm1;
 80 
 81 implementation
 82 
 83 {$R *.dfm}
 84 
 85 
 86 procedure TForm1.btnBuilderClick(Sender: TObject);
 87 var
 88   Builder: TJSONBuilder;
 89 begin
 90   Builder := TJSONBuilder.NewBuilder(TJsonFormatting.Indented);
 91   Builder
 92     .BeginObject
 93       .BeginArray(\'Transaction\')
 94         .BeginObject.Add(\'id\', 662713)
 95           .Add(\'firstName\', \'John\')
 96           .Add(\'lastName\', \'Doe\')
 97           .Add(\'price\', 2.1)
 98           .AddNull(\'parent_id\')
 99           .Add(\'validated\', True)
100         .EndObject
101         .BeginObject
102           .Add(\'id\', 662714)
103           .Add(\'firstName\', \'Anna\')
104           .Add(\'lastName\', \'Smith\')
105           .Add(\'price\', 4.5)
106           .AddNull(\'parent_id\')
107           .Add(\'validated\', False)
108         .EndObject
109         .BeginObject
110           .Add(\'id\', 662715)
111           .Add(\'firstName\', \'Peter\')
112           .Add(\'lastName\', \'Jones\')
113           .Add(\'price\', 3.6)
114           .AddNull(\'parent_id\')
115           .Add(\'validated\', True)
116         .EndObject
117       .EndArray
118     .EndObject;
119 
120   Memo1.Text := Builder.ToJSON;
121 
122 end;
123 
124 procedure TForm1.btnReaderClick(Sender: TObject);
125 var
126   Reader:TJsonObjectReader;
127 begin
128   Memo2.Clear;
129   Reader:=TJsonObjectReader.NewReader(Memo1.Text);
130 
131   while Reader.Read do
132     case Reader.TokenType of
133       TJsonToken.PropertyName:
134       Memo2.Lines.Add(Reader.Value.AsString);
135       TJsonToken.String:
136       Memo2.Lines[Memo2.Lines.Count-1] := Memo2.Lines[Memo2.Lines.Count-1] + \': \' +Reader.Value.AsString;
137     end;
138 end;
139 
140 procedure TForm1.FormCreate(Sender: TObject);
141 begin
142   ReportMemoryLeaksOnShutdown := True;
143 end;
144 
145 { TJSONBuilder }
146 
147 constructor TJSONBuilder.Create(const AFormatting: TJsonFormatting);
148 begin
149   FJsonBuilder := nil;
150   FStringBuilder := TStringBuilder.Create;
151   FStringWriter := TStringWriter.Create(FStringBuilder);
152   FJsonWriter := TJsonTextWriter.Create(FStringWriter);
153   FJsonWriter.Formatting := AFormatting;
154   inherited Create(FJsonWriter);
155 end;
156 
157 destructor TJSONBuilder.Destroy;
158 begin
159   FreeAndNil(FJsonWriter);
160   FreeAndNil(FStringWriter);
161   FreeAndNil(FStringBuilder);
162   inherited;
163 end;
164 
165 class destructor TJSONBuilder.Destroy;
166 begin
167   FreeAndNil(FJsonBuilder);
168 end;
169 
170 class function TJSONBuilder.NewBuilder(const AFormatting: TJsonFormatting): TJSONBuilder;
171 begin
172   if FJsonBuilder <> nil then
173     FreeAndNil(FJsonBuilder);
174 
175   FJsonBuilder := TJSONBuilder.Create(AFormatting);
176 
177   Result := FJsonBuilder;
178 end;
179 
180 function TJSONBuilder.ToJSON: string;
181 begin
182   Result := FStringBuilder.ToString;
183 end;
184 
185 { TJsonObjectReader }
186 
187 constructor TJsonObjectReader.Create(const AJson: string);
188 begin
189   FStringReader:= TStringReader.Create(AJson);
190   inherited Create(FStringReader) ;
191 end;
192 
193 class destructor TJsonObjectReader.Destroy;
194 begin
195   FreeAndNil(FJsonObjectReader);
196 end;
197 
198 destructor TJsonObjectReader.Destroy;
199 begin
200   FreeAndNil(FStringReader);
201   inherited;
202 end;
203 
204 class function TJsonObjectReader.NewReader(const AJson:string): TJsonObjectReader;
205 begin
206    if FJsonObjectReader <> nil then
207     FreeAndNil(FJsonObjectReader);
208 
209   FJsonObjectReader := TJsonObjectReader.Create(AJson);
210 
211   Result := FJsonObjectReader;
212 end;
213 
214 end.

运行效果如图：