浅谈Delphi高效使用TreeView - 癫狂编程
浅谈Delphi高效使用TreeView
本来我一直都是使用递归算法, 效率很低
下边这段代码是我原来写的
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procedure TForm1.GetDepartmentMsg;
var
Test, Test2 : TTreeNode;
procedure NodeAdd(Test : TTreeNode; DepartmentId : string);
var
Testlevel : TTreeNode;
TestQuery : TADOQuery;
begin
try
TestQuery := TADOQuery.Create(Nil);
TestQuery.Connection := ADOConnection1;
With TestQuery do
begin
Close;
SQL.Text := \'Select DepartmentID ,NAME from Department where DepartmentID like \'\'\'+DepartmentId+\'%\'\' and Len(DepartmentId) = \' + IntToStr(Length (DepartmentId) + 2) + \'Group by DepartmentID ,name order by DepartmentID \' ;
Open;
if Not IsEmpty then
begin
while not Eof do
begin
Testlevel := TreeView1.Items.AddChild(Test,TestQuery.fieldbyName(\'Name\').AsString + \' | \'+ TestQuery.fieldbyName(\'DepartmentId\').AsString);
NodeAdd(Testlevel,TestQuery.fieldbyName(\'DepartmentId\').AsString);
Testlevel.ImageIndex := Testlevel.Level -1;
Testlevel.SelectedIndex := Testlevel.Level -1;
Next;
end;
end;
end;
finally
TestQuery.free;
end;
end;
begin
Test := TreeView1.Items.Add(nil,\' ***** | 00\');
Test.ImageIndex := 1;
with Query1 do
begin
Close;
Sql.Text := \'Select * from Department where State = \'\'正常\'\' and DepartmentLevel = \'\'1\'\' \';
Open;
end;
Query1.First;
TreeView1.Items.BeginUpdate;
while not Query1.Eof do
begin
Test2 := TreeView1.Items.AddChild(Test,Query1.fieldbyName(\'Name\').AsString + \' | \'+ Query1.fieldbyName(\'DepartmentId\').AsString) ;
NodeAdd(Test2,Query1.fieldbyName(\'DepartmentId\').AsString);
Query1.Next;
end;
TreeView1.Items.EndUpdate;
Query1.Close;
end;
今天无事测试了这段代码 时间是6-7秒左右
下边这段改进后的,不使用递归
procedure TForm1.NewGetDepartmentMsg;
const
DivNum = 2;
var
nLevel: Integer;
pNodes: array[0..1023] of TTreeNode;
DepartmentID, Name: string;
Str: string;
begin
Str := \'Select DepartmentID, Name from Department order by DepartmentID\';
with adoquery1 do
begin
Close;
Sql.clear;
Sql.add(Str);
Open;
end;
TreeView1.Items.Clear;
TreeView1.Items.BeginUpdate;
pNodes[0] := TreeView1.Items.Add(nil, \'***\');
if Not ADOQuery1.IsEmpty then
while not ADOQuery1.Eof do
begin
DepartmentID := ADOQuery1.fieldbyName(\'DepartmentID\').AsString;
Name := ADOQuery1.fieldbyName(\'Name\').AsString;
nLevel := Length(DepartmentID) div DivNum ;
pNodes[nLevel] := TreeView1.Items.AddChild(pNodes[nLevel - 1], DepartmentID + \' | \' + Name);
ADOQuery1.Next;
end;
TreeView1.Items.EndUpdate;
ADOQuery1.Close;
end;
这个算法主要合理利用了 \'Select DepartmentID, Name from Department order by DepartmentID\' 来排序, 这就保证了
pNodes[nLevel] := TreeView1.Items.AddChild(pNodes[nLevel - 1], DepartmentID + \' | \' + Name);
他的上级结点不为空
这段代码我一测试, 大概是0.2秒左右, 数据和上边那段代码处理一样的数据
这样写肯定是有缺陷的, 也不是什么情况下都能使用
写得不对的地方,欢迎批评和指正,谢谢