Delphi使用ADO连接池(存储过程示例)

一个使用ADO连接池的示例,演示了TADOStoredProc动态参数的使用，带重连机制 =================== unit UnitDemo; interface uses Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms, Dialogs, StdCtrls; type TForm2 = class(TForm) Button1: TButton; procedure Button1Click(Sender: TObject); procedure FormCreate(Sender: TObject); procedure FormDestroy(Sender: TObject); private { Private declarations } public { Public declarations } end; var Form2: TForm2; //数据库服务器 gDBServer: String = '127.0.0.1'; / /数据库名称 gDBName: String = 'master'; //数据库用户名 gDBUser: String = 'sa'; //密码 gDBPass: String = '2001'; implementation {$R *.dfm} uses ADODB, UnitADOConnectionPool; const CreateSQL = 'create procedure TestMyPool (@type sysname) '#13#10+ 'as'#13#10+ 'select * from sysobjects where xtype=@type'#13#10+ 'return @@rowcount'; DeleteSQL = 'if Exists(select 1 from sysobjects where xtype=N''P'' and name=N''TestMyPool'')'#13#10+ ' drop procedure TestMyPool'; var gPoolMan: TADOConnPoolMan = Nil; procedure TForm2.Button1Click(Sender: TObject); var ADOObject:TADOConnPoolObject; ADOStoredProc:TADOStoredProc; Running :Integer; I: Integer; begin //取得一个存储过程资源（含一数据库有效连接） ADOObject := gPoolMan.CreateSP('TestMyPool'); if ADOObject = Nil then //取得资源失败 Exit; try ADOStoredProc := ADOObject.ExecObject as TADOStoredProc; Running := 2;//允许重试(两次)操作，以便在操作失败之后达到重连 while Running>0 do begin Dec(Running); if ADOObject.NeedRefresh then begin//判断是否有重连标志（比如数据库断开等，可能需要进行重连） if Not ADOObject.Reconnect then Exit; ADOObject.NeedRefresh := Not ADOStoredProc.Parameters.Refresh; if ADOObject.NeedRefresh then Exit; end; for I := 1(*Zero is the *Result* Parameter*) to ADOStoredProc.Parameters.Count - 1 do begin //========================= //传递参数 ADOStoredProc.Parameters.Items[I].Value := 'U'; //========================= end; if Running 0 then try //执行存储过程 ADOStoredProc.Open; //执行存储过程成功，退出循环进入后续的数据处理 break; except On E:Exception do begin //执行失败非程序级的异常通常有两种可能： //1.数据库连接断开 //2.自适合的参数传递当中可能存储过程已更新，参与不一致 //设置重连标志 ADOObject.NeedRefresh := True; //=================== //这里记录数据库操作失败日志 //=================== end; end; Exit; end; //========================== //从ADOStoredProc当中读取记录 ShowMessage(IntToStr(ADOStoredProc.Parameters.ParamByName('Result').Value)); //========================== //关闭存储对象的资源 ADOStoredProc.Close; finally //调用结束，释放资源 ADOObject.Free; end; end; procedure TForm2.FormCreate(Sender: TObject); var ADOConn:TADOConnection; begin (****************BEGIN*******************) (*注：仅为测试准备 *) //初始化测试环境 ADOConn := Nil; if Not TADOConnPoolMan.ConnectADO( gDBServer,gDBUser,gDBPass,gDBName,true,ADOConn) then Exit; try ADOConn.Execute(DeleteSQL); ADOConn.Execute(CreateSQL); finally try ADOConn.Close; except end; ADOConn.Free; end; (*****************END********************) //初始化连接池 gPoolMan := TADOConnPoolMan.Create(gDBServer,gDBUser,gDBPass,gDBName,true); end; procedure TForm2.FormDestroy(Sender: TObject); var ADOConn:TADOConnection; begin //释放连接池 if Assigned(gPoolMan) then gPoolMan.Free; (****************BEGIN*******************) (*注：仅为测试准备 *) //清理测试环境 ADOConn := Nil; if Not TADOConnPoolMan.ConnectADO( gDBServer,gDBUser,gDBPass,gDBName,true,ADOConn) then Exit; try ADOConn.Execute(DeleteSQL); finally try ADOConn.Close; except end; ADOConn.Free; end; (*****************END********************) end; end.