递归树与数据库关联修改.txt

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procedure TForm1.FormActivate(Sender: TObject);
var
 tNode: TTreeNode;
 i,nChildNum: Integer;
 sChildItem: string;
 pItem: PNode;
begin
 try
   TestTree.Items.Clear;           //清空树型列表
   TestTable.Active := true;       //打开表
   TestTable.FindKey(['ITEM']);    //定位记录到根节点
   tNode := TestTree.Items.Add(nil,TestTable.FieldByName('Name').AsString);    //添加根节点

   New(pItem);                     //保存根节点在树中的标识
   pItem.sItem := 'ITEM';
   tNode.Data := PItem;

   //用递归添加所有子节点
   nChildNum := TestTable.FieldByName('ChildNum').AsInteger;   //获得子节点数目
   for i := 1 to nChildNum do                                  //添加子节点
     begin
       sChildItem := 'ITEM_' + IntToStr(i);
       AddTreeChild(sChildItem,tNode);
     end;
   except
     Application.MessageBox('数据库出错！','错误');
   end
end;

//功能：递归函数，用来添加节点
//参数：sItem        节点在树中的标识
//      FatherNode   节点的父节点
procedure TForm1.AddTreeChild(sItem: string;FatherNode: TTreeNode);
var
 tNode: TTreeNode;
 i,nChildNum: Integer;
 sChildItem: string;
 pItem: pNode;
begin
 try
   TestTable.FindKey([sItem]);         //定位到该节点的记录
   tNode := TestTree.Items.AddChild(FatherNode,TestTable.FieldByName('Name').AsString);   //添加该节点

   New(pItem);                 //保存该节点在树中的标识
   pItem.sItem := sItem;
   tNode.Data := pItem;

   nChildNum := TestTable.FieldByName('ChildNum').AsInteger;      //添加该节点的所有子节点
   for i := 1 to nChildNum do
     begin
       sChildItem := sItem + '_' + IntToStr(i);
       AddTreeChild(sChildItem,tNode);         //递归调用
     end;
   except
     Application.MessageBox('数据库出错！','错误');
   end;
end;

//当选中一个节点时，显示节点的内容
procedure TForm1.TestTreeChange(Sender: TObject; Node: TTreeNode);
begin
 TestTable.FindKey( [ pNode(Node.Data).sItem ] );
 MemoTree.Text := TestTable.FieldByName('Text').AsString;
end;

procedure TForm1.FormClose(Sender: TObject; var Action: TCloseAction);
var
 i: Integer;
begin
 for i := 1 to TestTree.Items.Count do       //释放NEW的空间
   Dispose(TestTree.Items[i-1].Data);
 if TestTable.Active then                    //关闭表
   TestTable.Close;
end;

//右键选择添加时，为当前节点添加一个子节点
procedure TForm1.N1Click(Sender: TObject);
var
 tChildNode: TTreeNode;
 sChildItem: string;
 pItem: pNode;
begin
  tChildNode := TestTree.Items.AddChild(TestTree.Selected,'NEW');         //添加子节点

  sChildItem := pNode(TestTree.Selected.Data).sItem;               //保存子节点在树中的标识
  sChildItem := sChildItem + '_' + IntToStr(TestTree.Selected.Count);
  New(pItem);
  pItem.sItem := sChildItem;
  tChildNode.Data := pItem;

  try
    //定位到当前节点的记录，将其子节点数加一
    TestTable.FindKey( [ pNode(TestTree.Selected.Data).sItem ] );
    TestTable.Edit;
    TestTable.FieldByName('ChildNum').AsInteger := TestTable.FieldByName('ChildNum').AsInteger+1;
    TestTable.Post;
    //添加子节点记录
    TestTable.Insert;
    TestTable.FieldByName('Node').AsString := sChildItem;
    TestTable.FieldByName('ChildNum').AsInteger := 0;
    TestTable.FieldByName('Name').AsString := 'NEW';
    TestTable.Post;
   except
     Application.MessageBox('数据库出错！','错误');
   end;
end;

//右键选择删除时，删除当前节点和它的所有后代
procedure TForm1.N2Click(Sender: TObject);
begin
 if pNode(TestTree.Selected.Data).sItem = 'ITEM' then
   begin
     Application.MessageBox('您不能删除根节点！','对不起');
     Exit;
   end;
 try
   TestTable.FindKey( [ pNode(TestTree.Selected.Parent.Data).sItem ] );
   TestTable.Edit;
   TestTable.FieldByName('ChildNum').AsInteger := TestTable.FieldByName('ChildNum').AsInteger - 1;
   TestTable.Post;
 except
   Application.MessageBox('数据库出错！','错误');
 end;
 DeleteNode(TestTree.Selected);
end;

procedure TForm1.DeleteNode(CurrentNode: TTreeNode);
var
 i,nChildNum: Integer;
 tChildNode: TTreeNode;
begin
 nChildNum := CurrentNode.Count;
 for i := 1 to nChildNum do
   begin
     tChildNode := CurrentNode.GetLastChild;
     DeleteNode(tChildNode);
   end;
 try
   TestTable.FindKey( [ pNode(CurrentNode.Data).sItem ] );
   TestTable.Delete;
 except
   Application.MessageBox('数据库出错！','错误');
 end;
 TestTree.Items.Delete(CurrentNode);
end;

//保存当前节点的内容
procedure TForm1.Button1Click(Sender: TObject);
begin
 try
   TestTable.FindKey( [ pNode(TestTree.Selected.Data).sItem ] );
   TestTable.Edit;
   TestTable.FieldByName('Text').AsString := MemoTree.Text;
   TestTable.Post;
 except
   Application.MessageBox('数据库出错！','错误');
 end;
end;

//当更改节点名称时，同时修改数据库
procedure TForm1.TestTreeEdited(Sender: TObject; Node: TTreeNode;
 var S: String);
begin
 try
   TestTable.FindKey( [ pNode(Node.Data).sItem ] );
   TestTable.Edit;
   TestTable.FieldByName('Name').AsString := S;
   TestTable.Post;
 except
   Application.MessageBox('数据库出错！','错误');
 end;
end;

procedure TForm1.TestTreeCustomDrawItem(Sender: TCustomTreeView;
 Node: TTreeNode; State: TCustomDrawState; var DefaultDraw: Boolean);
begin
if Node.Expanded = True then
      Node.StateIndex := 1
 else
      Node.StateIndex  :=2;

end;

end.