前面的树形图，也就是TreeView一般读取的都是Json数据

例如

[{dispCode:01,dispName:'上级1, children: [

下面代码，读取的数据表里需要有以下字段 

DispCode：编码 DispName：名称  level_num：级次

实现思路是先生成一个个对象（TeleItem），再将对象转化成JSONObject对象，再输出JSON文本。

可以调用REs.jSON里的TJson.ObjectToJsonString直接生成JSON文本，但是他会给输入增加一个Name叫XXXhelper。不是我要的。所以最终只能先自行将

TeleItem生成JSONObject再将jsonobjct生成Jsonobject。

Teleitem

实现代码

  1 unit UntTree;
  2 
  3 interface
  4 uses System.Generics.Collections, FireDAC.Comp.Client,JSON,REST.Json,System.SysUtils;
  5 type
  6   TeleItem=class
  7     dispcode:string;    //编码
  8     dispName:String;      //名称
  9     level_num:integer;     //级次
 10     children:TList<Teleitem>;    //子级
 11     destructor Destroy; override;
 12 
 13   end;
 14 
 15 
 16 function IntTree(FDQuery:TFDQuery;tableName,SetCode:String):String;    //方法1  先生成Teleitem再生成Jsonobject
 17 function LoadEleTree(FDQuery:TFDQuery;tableName,SetCode:String):String;    //方法2 直接生成Jsonobject
 18 
 19 implementation
 20 function LoadEleTree(FDQuery:TFDQuery;tableName,SetCode:String):String;
 21 var
 22  FJOlist:TList<TJSONObject>;
 23  FJData:TJSONObject;
 24  I,levelnum,J:integer;
 25  cDispCode:string;
 26  JOParent,JO:TJsonObject;
 27  JaData,Children:TJSONArray;
 28  begin
 29   FJData:=TJsonObject.Create;
 30   FJOlist:=TList<TJSONObject>.Create;
 31   JaData:=TJSONArray.Create;
 32   FJData.AddPair('data',JaData);
 33   FDQuery.Close;
 34   FDQuery.open('select * from '+tableName +' where set_Code='''+setCode+''' and is_leaf<>10');
 35   FDQuery.FetchAll;
 36   while Not FDQuery.Eof do
 37    begin
 38      try
 39         JO:=TJSONObject.Create;
 40        J:=FDQuery.FieldByName('level_num').AsInteger;
 41        cDispCode:=FDQuery.FieldByName('disp_Code').asstring;
 42        JO.AddPair('DispCode',cdispCode);
 43        JO.AddPair('DispName',FDQuery.FieldByName('disp_Name').asstring);
 44        JO.AddPair('LevelNum',INTTOSTR(J));
 45 
 46        FJOlist.Add(JO);
 47         if FDQuery.FieldByName('level_num').asinteger<>1 then
 48            begin
 49              for  I := 0 to FJOlist.Count-1 do
 50               begin
 51                JOParent:=FJOlist[I];
 52                levelnum:=JOParent.Values['LevelNum'].Value.tointeger;
 53               if levelnum+1<>J then Continue;
 54                 var dispCode:=JOParent.Values['DispCode'].Value;
 55                 if Pos(dispcode,cdispCode)=1 then
 56                  begin
 57                    if not Assigned(JOParent.Values['Children']) then
 58                      begin
 59                        Children:=TJSONArray.Create;
 60                        JOParent.AddPair('Children',Children);
 61                      end else
 62                      Children:=JOParent.Values['Children'] as TJSONArray;
 63                    Children.Add(JO);
 64                    break;
 65                  end;
 66               end;
 67            end else
 68          JaData.Add(JO);
 69      finally
 70        FDQuery.Next;
 71      end;
 72    end;
 73   Result:=FJData.ToJSON();
 74   FJData.Free;
 75   FJOlist.Free;
 76  end;
 77 function IntTree(FDQuery:TFDQuery;tableName,SetCode:String):String;
 78 var
 79   I:integer;
 80   dispcode:String;
 81   Data:TJSONObject;
 82   FList,FTree:TList<TeleItem>;
 83    {$REGION 'ConvertToObject'}
 84     procedure ConvertToObject(Item:Teleitem;var Perent:TJSONArray);
 85     var
 86      aItem:TJSONObject;
 87      I:Integer;
 88 
 89      begin
 90       aitem:=TJSONObject.Create;
 91       aitem.AddPair('dispcode',item.dispcode);
 92       aitem.AddPair('dispname',item.dispname);
 93       Perent.add(aitem);
 94       IF Not Assigned(Item.children) then Exit;
 95       var P:=TJSONArray.Create;
 96       aitem.AddPair('children',P);
 97       For I:=0 to item.children.count-1 do
 98        begin
 99          ConvertToObject(item.children[I],P);
100        end;
101 
102      end;
103    {$ENDREGION 'ConvertToObject'}
104  begin
105     FDQuery.Close;
106     FDQuery.open('select * from '+tableName +' where set_Code='''+setCode+''' and is_leaf<>10');
107     FDQuery.FetchAll;
108     FList:=TList<Teleitem>.create;
109     FTree:=TList<Teleitem>.create;
110     while Not FDQuery.eof do
111      begin
112        try
113          Var AEle:=TEleitem.create;
114             aEle.dispCode:=FDQuery.FieldByName('disp_Code').asstring;
115             aele.dispName:=FDQuery.fieldByName('disp_Name').asstring;
116             AEle.level_num:=FDQuery.FieldByName('level_num').asinteger;
117             FList.Add(AEle);
118             if FDQuery.FieldByName('level_num').asinteger<>1 then
119              begin
120                for I := 0 to Flist.Count-1 do
121                 begin
122                 if Flist[I].level_num+1<>AEle.level_num then Continue;
123                   dispCode:=Flist[I].dispCode;
124                   if Pos(dispcode,aEle.dispCode)=1 then
125                    begin
126                      if not Assigned(Flist[I].children) then
127                        Flist[I].children:=TList<Teleitem>.create;
128                      FList[I].children.Add(aele);
129                      break;
130                    end;
131 
132                 end;
133               end else
134               FTree.Add(Aele);
135        finally
136          FDQuery.Next;
137        end;
138      end;
139 
140     Data:=TJSONObject.create;
141     var P:=TJSONArray.Create;
142     data.AddPair('data',P);
143     for I := 0 to FTree.Count-1 do
144      begin
145       ConvertToObject(FTree[I],P);
146      end;
147    Result:=data.ToJSON();
148    data.Free;
149    for I :=FList.count-1 downto 0 do
150     begin
151       Flist[I].Free;
152     end;
153     FList.Free;
154     FTree.Free;
155  end;
156 { TeleItem }
157 
158 destructor TeleItem.Destroy;
159 begin
160   if Self.children<>nil then
161     Self.children.Free;
162 end;
163 
164 end.

最终的结果如下，是一个json文本，然后前端如何生成Tree，自行研究