我做了一個關於動態增加、修改、刪除樹形結構的程序！願與大家分享（附源代碼）！！！

    procedure LoadTree(treeDB:TDBDataSet);//初始化樹
    procedure UpdateTree(curNode:TTreenode; nodeTxt:string; state:string);//更新樹
    function  GetNodeLevel(sFormat,sCode:string):integer; //獲得節點層數
    function  GetNodeItem(sCode:string):integer;//獲得item

    { Public declarations }
  end;

    const
  CTreeCodeFormat=122222;
  cTreeMaxLevel=6;
  CTreeRootTXT=所有圖書;

var
  tsgzlfrom: Ttsgzlfrom;
  _err:integer;
  curUser:string[10];
  mystate:string;
  gNodeId:string;
  gNodelevel:integer;
  gNode:TtreeNode;
  mynode:array[0..6] of TTreenode;
  i,Already,CurMode:integer;
  currow:integer;
  iniFile:string;
  HasSub:String;

  level:Integer;

  implementation

uses bgNewunit;

{$R *.DFM}

procedure TtsgzlFrom.LoadTree(treeDB:TDBDataSet);//初始化樹
var curID,nodeTxt:string;
    level,num:integer;
begin
    //初始化變量
    Screen.Cursor:=crHourGlass;
    tree.Enabled:=True;
    tree.Items.Clear;
    level:=1 ;
    num:=1;
    tree.items.clear;
    //設置根節點
    mynode[level]:=Tree.items.add(Tree.Topitem,cTreeRootTxt);
    mynode[level].ImageIndex:=0;
    mynode[level].SelectedIndex:=1;
    //遍歷數據表，利用編碼字段記錄排序規律，依次添加樹節點
    with TreeDb do
    begin
       try
       if not Active then open;
       first;
       while not Eof do
       begin
         curID:=trim(FieldByName(tsglb).AsString);
         nodeTxt:=curID+-+trim(FieldByName(tsglbn).AsString);
         level:=GetNodeLevel(cTreeCodeFormat,curID);
         //這裡返回代碼的層次數
         if level>0 then
         begin
  //增加下一節點時，用添加子節點的方法可輕松實現節點間的層次關系。
         //注意：這裡的父節點是用當前節點的上一級節點mynode[level-1]
            mynode[level]:=Tree.Items.AddChild(Mynode[level-1],NodeTxt);
            mynode[level].ImageIndex:=2;
            mynode[level].SelectedIndex:=3;
         end;
         next;//下一條記錄
       end;
       finally;
         close;
       End;
       mynode[1].expand(False);
       Screen.Cursor:=crHourGlass;
     end;
end;

function TtsgzlFrom.GetNodeLevel(sFormat,sCode:string):integer;
var i,iLen:integer;
begin
  level:=-1  ;
  iLen:=0;
  if (sFormat<>) and (sCode<>) then
    for i:=1 to Length(sFormat) do //分析編碼格式，找出當前代碼層次
    begin
      iLen:=iLen+StrToInt(sFormat[i]);
      if Length(sCode)=iLen then
      begin
        level:=i;
        break;
      end;
    end;
  result:=level;
end;

Function TtsgzlFrom.GetNodeItem(sCode:string):integer;//獲得item
var i,iCount,val:integer;
    tmp:string;
begin
  Result:=0;
  iCount:=Tree.Items.Count;
  if iCount=0 then exit;
  val:=0;
  for i:=1 to iCount-1 do
  begin
     Tmp:=Tree.Items.Item[i].Text;
     Tmp:=Copy(Tmp,0,pos(-,Tmp)-1);
     if Tmp=sCode then begin
        val:=i;
        Break;
     end;
  end;
  result:=val;
end;

procedure TtsgzlFrom.UpdateTree(curNode:TTreenode; nodeTxt:string; state:string);
Begin
  if  state=add   then
    begin
      curNode:=Tree.Items.addchild(curNode,nodeTxt);
      curNode.ImageIndex:=2;
      curnode.SelectedIndex:=3;
    end;
  if state=del then  curNode.delete;
  if state=edi then  curNode.Text:=nodeTxt;
end;