Delphi中Json格式读写

时间：2014-06-05 08:50:10 阅读：406 评论：0 收藏：0 [点我收藏+]

Json是一种轻量级数据传输格式，广泛应用互联网和各应用中，json主要采用键值对来表示数据项，多个数据项之间用逗号分隔，也可以用于数组。下面注重介绍一下在delphi中使用json，在delphi中使用json常用superobject单元文件，该文件可以在网上下载，最初接触json是在2011年，好久没用这不刚好有项目要用到又折腾了好久，下面做了一个简单的Demo，方便以后忘了能随时查看，具体的json使用可以参看万一老师的博客，记录的很详细，下面的demo主要是将数据库记录转换为json格式，然后进行解析。具体源码如下。

新建一个delphi应用程序，在窗体上放置table组件，连接数据DBDEMOS，连接表customer.db，active设置为true。具体文件如下：

delphi工程文件如下

program Project1;

uses
Forms,
Unit1 in ‘Unit1.pas‘ {Form1};

{$R *.res}

begin
Application.Initialize;
Application.CreateForm(TForm1, Form1);
Application.Run;
end.

单元文件如下：

unit Unit1;

interface

uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
Dialogs, StdCtrls, Grids, DBGrids, DB, DBTables;

type
TForm1 = class(TForm)
mmo1: TMemo;
tbl1: TTable;
ds1: TDataSource;
btn1: TButton;
btn2: TButton;
btn3: TButton;
procedure btn1Click(Sender: TObject);
procedure btn2Click(Sender: TObject);
procedure btn3Click(Sender: TObject);
private
{ Private declarations }
public
{ Public declarations }
end;

var
Form1: TForm1;

implementation

{$R *.dfm}

uses superobject;

procedure TForm1.btn1Click(Sender: TObject);
var
jo,jt:ISuperObject;
begin
jo:=SO();
jt:=SO();
jo.S[‘xm‘]:=‘张三‘;
jo.I[‘age‘]:=25;
jo.S[‘sex‘]:=‘男‘;
jt.O[‘person‘]:=jo;
ShowMessage(jt.AsString);
ShowMessage(jt.O[‘person‘].S[‘xm‘]);
end;

procedure TForm1.btn2Click(Sender: TObject);
var
i:Integer;
jfields,jitems,jo:ISuperObject;
begin
mmo1.Clear;
jitems:=SA([]);
jo:=SO();
with tbl1 do
begin
First;
while not eof do
begin

jfields:=SO();
for i:=0 to FieldCount-1 do
begin
if Fields[i].DataType=ftDateTime then
jfields.S[Fields[i].FieldName]:=FormatDateTime(‘yyyy-mm-dd hh:mm:ss‘,Fields[i].AsDateTime)
else
jfields.S[Fields[i].FieldName]:=Fields[i].AsString;
end;
jitems.AsArray.Add(jfields);
Next;
end;
end;
jo.O[‘records‘]:=jitems;
mmo1.Lines.Add(jo.AsString);
end;

procedure TForm1.btn3Click(Sender: TObject);
var
jo,m:ISuperobject;
i,j:Integer;
tt:TSuperArray;
s:string;
lst:TStringList;
begin
if mmo1.Text<>‘‘ then
begin
lst:=TStringList.Create;
jo:=so(mmo1.Text);
tt:=jo.O[‘records‘].AsArray;
for i:=0 to tt.Length-1 do
begin
s:=‘‘;
for j:=0 to tbl1.FieldCount-1 do
begin
if s=‘‘ then
s:=tt.O[i].S[tbl1.Fields[j].FieldName]
else
s:=s+‘ ‘+tt.O[i].S[tbl1.Fields[j].FieldName]
end;
lst.Add(s);
end;
ShowMessage(lst.Text) ;
lst.Free;
end;
end;

end.

dfm文件如下：

object Form1: TForm1
Left = 312
Top = 70
Width = 410
Height = 382
Caption = ‘json读写‘
Color = clBtnFace
Font.Charset = DEFAULT_CHARSET
Font.Color = clWindowText
Font.Height = -11
Font.Name = ‘MS Sans Serif‘
Font.Style = []
OldCreateOrder = False
PixelsPerInch = 96
TextHeight = 13
object mmo1: TMemo
Left = 0
Top = 0
Width = 394
Height = 249
Align = alTop
TabOrder = 0
end
object btn1: TButton
Left = 23
Top = 264
Width = 75
Height = 25
Caption = ‘简单读写‘
TabOrder = 1
OnClick = btn1Click
end
object btn2: TButton
Left = 121
Top = 264
Width = 105
Height = 25
Caption = ‘读数据库记录‘
TabOrder = 2
OnClick = btn2Click
end
object btn3: TButton
Left = 253
Top = 263
Width = 75
Height = 25
Caption = ‘解析json‘
TabOrder = 3
OnClick = btn3Click
end
object tbl1: TTable
Active = True
DatabaseName = ‘DBDEMOS‘
TableName = ‘customer.db‘
Left = 288
Top = 152
end
object ds1: TDataSource
DataSet = tbl1
Left = 104
Top = 176
end
end

其中有些版本superobject的hash方法有编译指令，我使用时报错，将其去掉改为如下:

class function TSuperAvlEntry.Hash(const k: SOString): Cardinal;
var
h: cardinal;
i: Integer;
begin
h := 0;
for i := 1 to Length(k) do
h := h*129 + ord(k[i]) + $9e370001;
Result := h;
end;

程序运行结果如下：

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