树的快速创建算法,只需读一次数据库.

树的快速创建算法,只需读一次数据库.

unit U_CreateTree;

interface

uses
  Classes, ComCtrls, ADODB, SysUtils;

type
  PPNodedata=^TNodeData;
  TNodeData = record
    ID:integer;//节点编号
    PID:Integer;//父节点编号
    Name:string;//节点名称
    child:PPNodedata;//孩子节点
    brather:PPNodedata;//兄弟节点
  end;
  PNodeData = PPNodeData;
  TTreeFill1 = class(TThread)
    TV: TTreeView;
    RootID:Integer;
    ptr:PPNodeData;
    root:PPNodeData;//根节点
    PointNode:PPNodeData;
    s:array[0..10000] of PPNodeData;
   constructor Create(Root_Id:integer;ATreeView: TTreeView);
  private
    procedure AddTree(Node: TTreeNode; PN: PNodeData);
  protected
    procedure Execute; override;
  end;

implementation

uses
  U_Main, DateUtils;

var count,nodeCount:Integer;
//----------
constructor TTreeFill1.Create(Root_Id:integer;ATreeView:TTreeView);
begin
  TV:= ATreeView;
  TV.Items.Clear;
  RootID:=Root_Id;
  inherited Create(False);
end;
//----------
procedure TTreeFill1.Execute;
var Query: TADOQuery;
    i,j:Integer;
    Node: TTreeNode;
begin
  FreeOnTerminate := True;
  TV.Items.Clear;
  with Query do
    begin
      Query := TADOQuery.Create(nil);
      Connection := frm_Main.ADOC_SQL;//需要更改
      Close;
      SQL.Clear;
      SQL.Add('Select * from 部门表 order by 部门编号 ');
      Open;
      first;
      count:=recordcount;
      if count>0 then
        begin
          for i:=0 to recordcount-1 do
          begin
          new(PointNode);
          PointNode^.child:=nil;
          PointNode.brather:=nil;
          PointNode^.ID:=fieldbyname('部门编号').AsInteger;
          PointNode^.PID:=fieldbyname('父部门编号').AsInteger;
          PointNode^.Name:=fieldbyname('部门名称').AsString;
          s[i]:= PointNode;
          next;
          end;
        end;
      free;
    end;
//------创建树----------
for i:=0 to count-1 do
  begin
    for j:=0 to count-1 do
     if s[i]^.PID=s[j]^.ID then
       begin
         if s[j]^.child=nil then
          s[j]^.child:=s[i]
         else
          begin
          ptr:= s[j]^.child;
          while (ptr.brather<>nil) do
          ptr:=ptr^.brather;
          ptr.brather:=s[i];
          end;
        end;
  end;
  for i:=0 to count-1 do
    if s[i]^.ID=RootID then
    begin
      root:=s[i]; //根节点
      break;
    end;
  Node:=TV.Items.AddObject(nil,Root^.Name,Root);//创建树的根节点
  nodeCount:=0;
  Node.ImageIndex := 0;
  Node.SelectedIndex := 2;
  AddTree(Node,root);
end;

procedure TTreeFill1.AddTree(Node:TTreeNode;PN:PNodeData);
var
   nNode: TTreeNode;
   PNode,q: PNodeData;
begin
PNode:=PN;
if PNode.child<>nil then
  begin
     q:=PNode.child;
     while (q<>nil) do
      begin
       nNode:=TV.Items.AddchildObject(Node,q^.Name,q);
       nodeCount:=nodeCount+1;
       AddTree(nNode,q);
       q:=q^.brather;
      end;
  end;
end;

end.