1． 先建立编码表：city_tree(bianma,cityname)。
2． 新建一个项目，按默认保存。
3． 新建一公共单元pubvar，在其中定义以下常量：
Const
cTreeCodeFormat = ‘222’;//编码格式为 XX XX XX
cTreeMaxLevel = 3;//最大编码层次
cTreeRootTxt = ‘城市’;//树根结点名称
这样做为了提高程序的通用性，以后用于其他代码字典的维护时，只需要更改这些特征常量。
4． 程序源代码：
unit Unit1;
interface
uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms, Dialogs, DB, DBTables, ImgList, ComCtrls , PubVar, Grids, DBGrids, Menus , StrUtils, StdCtrls;
type
TForm1 = class(TForm)
Tree: TTreeView;
ImageList1: TImageList;
Table1: TTable;
DataSource1: TDataSource;
DBGrid1: TDBGrid;
PopupMenu1: TPopupMenu;
AddMenu: TMenuItem;
DeleteMenu: TMenuItem;
RenameMenu: TMenuItem;
Query1: TQuery;
DataSource2: TDataSource;
procedure AddMenuClick(Sender: TObject);//点击增加子项菜单
procedure RenameMenuClick(Sender: TObject);//点击重命名菜单
procedure DeleteMenuClick(Sender: TObject); //点击删除该项菜单
procedure FormCreate(Sender: TObject);
procedure TreeClick(Sender: TObject);
private
{ Private declarations }
public
{ Public declarations }
procedure LoadTree(treeDB:TDBDataSet);//初始化树
procedure UpdateTree(curNode:TTreenode; nodeTxt:string; state:string);//更新树
function GetNodeLevel(sFormat,sCode:string):integer;//获得节点层数
function GetCurrChildNodeMaxMa(curNode:TTreenode):string;
//获得当前节点子节点的最大编码
function GetCurrentNodeBianma(curNode:TTreenode):string;//获得当前节点的编码
procedure UpdateTable(bianma:string; cityname:string ;state:string); //更新数据库
end;
var
Form1: TForm1;
CurrentTreeNode: TTreeNode;
// AddChildeTreeNode: TTreeNode;
// flag:boolean; //用于标识是否需要在重命名树结点时更新数据
implementation
uses AddChildUnit,RenameItemUnit;
{$R *.dfm}
procedure TForm1.LoadTree(treeDB:TDBDataSet);//初始化树
var
curID,nodeTxt:string;
level:integer;
mynode:array[0..3] of TTreenode;
begin //初始化变量
Screen.Cursor:=crHourGlass;
tree.Enabled:=True;
tree.Items.Clear;
level:=0 ;
//设置根节点
mynode[level]:=tree.items.add(Tree.Topitem,cTreeRootTxt);
mynode[level].ImageIndex:=1;
//遍历数据表，利用编码字段记录排序规律，依次添加树节点
with treeDB do
begin
try
if not Active then open;
first;
while not Eof do
begin
curID:=trim(FieldByName('bianma').AsString);
nodeTxt:=curID+'-'+trim(FieldByName('cityname').AsString);
level:=GetNodeLevel(cTreeCodeFormat,curID);
//这里返回代码的层次数
if level>0 then
begin
//增加下一节点时，用添加子节点的方法可轻松实现节点间的层次关系
//注意：这里的父节点是用当前节点的上一级节点mynode[level-1]
mynode[level]:= tree.items.addchild(mynode[level-1],nodeTxt);
mynode[level].ImageIndex:=2;
end;
next;//下一条记录
end;
finally
close;
End;
mynode[0].expand(False);
Screen.Cursor:=crDefault;
end;
end;
function TForm1.GetNodeLevel(sFormat,sCode:string):integer;//获得节点层数
var i,level,iLen:integer;
begin
level:=-1 ;
iLen:=0;
if (sFormat<>'') and (sCode<>'') then
for i:=1 to Length(sFormat) do //分析编码格式，找出当前代码层次
begin
iLen:=iLen+StrToInt(sFormat);
if Length(sCode)=iLen then
begin level:=i; break; end;
end;
result:=level;
end;
//以下过程在新增、删除、修改记录时，同步更新树形结构
procedure TForm1.UpdateTree(curNode:TTreenode; nodeTxt:string; state:string);
Begin
if UpperCase(state)='ADD' then
begin
curNode:=tree.items.addchild(curNode,nodeTxt);
curNode.ImageIndex:=2;
end;
if UpperCase(state)='DEL' then
begin
curNode.DeleteChildren;
curNode.delete;
end;
if UpperCase(state)='EDI' then curNode.Text:=nodeTxt;
end;
procedure TForm1.AddMenuClick(Sender: TObject);//点击增加子项菜单
var AddChildText, AddTableText,maxbianma : string;
begin
AddChildForm.Label1.Caption:='为"'+CurrentTreeNode.Text+'"增加子项 ';
if AddChildForm.ShowModal=mrOk then
begin
AddChildText:=AddChildForm.Edit1.Text;
maxbianma:=GetCurrChildNodeMaxMa(CurrentTreeNode);
if (CurrentTreeNode.Text='城市') and (maxbianma='1000') then
maxbianma:='11'//如果当前节点为根节点，且只有一个子节点，使增加节点编码为11
else if CurrentTreeNode.Text='城市' then
maxbianma:=IntToStr(StrToInt(LeftStr(maxbianma,2))+1)
else
maxbianma:=IntToStr(StrToInt(maxbianma)+1); //使子项编码自动增1
if maxbianma<>'0' then
begin
//增加树子层
AddTableText:=maxbianma+'-'+AddChildText;
UpdateTree(CurrentTreeNode,AddTableText,'add'); //更新树
UpdateTable(maxbianma,AddChildText,'add'); //更新表
ShowMessage('添加成功!');
end
else ShowMessage('此层为最低子层，不能在该层增加子层');
AddChildForm.Edit1.Text:='';
end;
end;
function TForm1.GetCurrChildNodeMaxMa(curNode:TTreenode):string;
//获得当前节点子节点的最大编码
var
aSQL,maxbianma:string;
li_pos:integer;
begin
li_pos:=pos('-',curNode.Text);
if li_pos=7 then
begin result:='-1'; exit; end;
if (li_pos=0) and (not(curNode.HasChildren)) then // 如果当前节点为根节点并且没有子节点
begin
result:='9'; //使根节点第一个节点编码为10
exit;
end
else begin
aSQL:='select bianma from city_tree where bianma like "' + MidStr(curNode.Text, 1, li_pos-1) + '%"';
Query1.UnPrepare;
Query1.Close;
Query1.SQL.Clear;
Query1.SQL.Text:=aSQL;
Query1.Prepare;
Query1.ExecSQL;
Query1.Active:=true;
Query1.Last;
maxbianma:=Query1.fieldbyname('bianma').AsString;
if Query1.RecordCount=1 then//如果当前项没有子项
maxbianma:=maxbianma+'00';
Query1.Active:=false;
end;
result:=maxbianma;
end;
procedure TForm1.RenameMenuClick(Sender: TObject);//点击重命名菜单
var
bianma:string;
itemtext:string; //用于重命名时保存输入的Edit.text
begin
RenameItemForm.Label1.Caption:='将"'+CurrentTreeNode.Text+'"命名为 ';
if RenameItemForm.ShowModal=mrOk then
begin
itemtext:=RenameItemForm.Edit1.Text;
bianma:=GetCurrentNodeBianma(CurrentTreeNode);
Table1.Locate('bianma',bianma,[]);
UpdateTable('',itemtext,'edi');
itemtext:=bianma+'-'+itemtext;
UpdateTree(CurrentTreeNode,itemtext,'edi');
ShowMessage('重命名成功!');
end;
end;
//以下过程在新增、删除、修改记录时，同步更新数据库表
procedure TForm1.UpdateTable(bianma:string; cityname:string ;state:string); //更新数据库
begin
if state='add' then
begin
Table1.Active:=True;
Table1.Insert;
Table1.SetFields([bianma,cityname]);
Table1.Post;
end;
if state='del' then
begin
Table1.Active:=True;
Table1.Locate('bianma',bianma,[]);
Table1.Delete;
end;
if state='edi' then
begin
Table1.Edit;
Table1.FieldByName('cityname').AsString:=cityname;
Table1.Post;
end;
end;
procedure TForm1.DeleteMenuClick(Sender: TObject); //点击删除该项菜单
var
bianma:string;
begin
CurrentTreeNode.expand(False);
if CurrentTreeNode.Text='城市' then //如果当前节点为根节点
begin
ShowMessage('不能删除根节点');
exit;//退出该过程
end;
if CurrentTreeNode.HasChildren then //如果当前节点具有子项
begin
ShowMessage('请先删除其子项');
exit;//退出该过程
end;
if Application.MessageBox(PChar('真的要删除"'+CurrentTreeNode.Text+'"这项吗?'),'警告',MB_YESNO)=mrYES then
begin
bianma:=GetCurrentNodeBianma(CurrentTreeNode);
UpdateTree(CurrentTreeNode,'','del');
UpdateTable(bianma,'','del');
ShowMessage('删除成功!');
Table1.Refresh;//更新TBGrid控件中的显示
Table1.Active:=true;
CurrentTreeNode:=Form1.tree.selected;
end;
end;
function TForm1.GetCurrentNodeBianma(curNode:TTreeNode):string;//获得当前节点的编码
var
li_pos:integer;
bianma:string;
begin
li_pos:=pos('-',curNode.Text);
bianma:=MidStr(curNode.Text,1,li_pos-1);
result:=bianma;
end;
procedure TForm1.FormCreate(Sender: TObject);
begin
LoadTree(Table1);
Table1.Active:=true;
end;
procedure TForm1.TreeClick(Sender: TObject);
begin
CurrentTreeNode:=Form1.tree.selected; //获得当前节点
end;
end.
unit PubVar;
interface
uses
SysUtils, WinTypes, WinProcs, Messages, Classes, Graphics, Controls, Forms, DbTables, StdCtrls, ExtCtrls, Buttons, Dialogs,Registry,Db, ComCtrls;
const
cTreeCodeFormat='222'; //编码格式:xx xx xx
cTreeMaxLevel=3; //最大编码(树节点)层次
cTreeRootTxt='城市'; //树的根节点名称
implementation
end.
