使用Dispatch模式设计信息上报审批功能

在做一个教育系统的项目，遇到一个这样的需求，下级部门要向上级部门上报各种申请共有10种左右，在上级的界面里，需要列出所有下属部门未审批的申请，同时根据不同的信息，调出不同的处理界面来。具体上报的消息类型，将来可能扩充。如果采用一般的做法，那么，就是在点击某一条消息的时候，根据消息id，判断属于什么类型的消息，然后调用相对应的处理过程：If msgid=1 then //
else if mesid=2 then //…..这样的方式日后维护起来麻烦，所以打算采用设计模式里的Dispatch模式进行设计。TfrmMsgList是消息列表的窗体，用户点击了某一条消息后，直接SendMessage(Dispatch,MsgID)给dispatcher。Dispatcher里面申明了每个消息id对应的消息处理函数，只需要直接分发就可以了，类似消息处理过程。点击消息的时候：procedure TfrmMsgList.HandleUploadMsg;var MsgID,msgCode: integer; SenderCode: pstring;begin if lstMsgs.Selected = nil then exit; MsgID := StrToInt(pstring(lstMsgs.Selected.Data)^); MsgCode := fMsgs.GetMsgCode(msgID); new(SenderCode); SenderCode^ := lstMsgs.Selected.Caption; SendMessage(MsgDisp.Handle,MsgCode,integer(SenderCode),MsgID);end;而在dispatch单元：/// <summary>/// 消息分发类，首先定义消息参数，消息参数等于数据库里的消息码，然后定义对于每个消息的处理/// 过程。使用的时候，用户选择了某条消息，只要把消息码post过来，/// 比如：/// SendMessage(MsgDisp.Handle,MsgCode,integer(SenderCode),MsgID);/// </summary>/// <author> bohe </author>/// <date> 2005-04-06 </date>unit untMsgDisp;
interface
uses SysUtils, Windows, Messages, Classes, Graphics, Controls, Forms, Dialogs, contnrs, unt_SignBase;
const WM_MSGSIGNED = WM_USER + 103; //消息已经审批了的通知消息，通知owner WM_NEWSTU = 10010; //：上报新生 WM_EDUINFO = 10015; {上报学籍信息} WM_STUMOVE = 10020; //上报学生变动 WM_SCHINFO = 10030; //上传学校信息 WM_SCHLIB = 10040;//：上报学校信息库 WM_CHANGENAME = 10050;//改名申请
WM_STATCLASS = 11010;//上报班级升学统计 WM_STATSTATUS = 11020; //上报学额巩固统计 WM_STATEDU = 11030; //：上报在校生统计 WM_STATENROLL = 11040; //上报服务区适龄儿童入学统计 WM_STATGRADUATE = 11060; //上报毕业生统计信息 WM_BURINFO = 11050; //上报管理部门基本信息
type //TMsgEvent = procedure(varMsg: TMessage); TfrmSignBaseClass = class of Tfrm_SignBase;
TMsgDisp = class(TWinControl) private fMsgList: TObjectList; frmSign: Tfrm_SignBase; procedure SignMsg(TfrmClass: TfrmSignBaseClass; Message: TMessage); procedure NotifySigned; public //constructor Create(); //destructor Destroy; override; //procedure RegisterMsg(Message: integer; MsgEvent: TMsgEvent); procedure WMNewStu(var Message: TMessage); message WM_NEWSTU; procedure WMEduInfo(var Message: TMessage); message WM_EDUINFO; procedure WMStuMove(var Message: TMessage); message WM_STUMOVE; procedure WMSchInfo(var Message: TMessage); message WM_SCHINFO; procedure WMSCHLIB(var Message: TMessage); message WM_SCHLIB; procedure WMCHANGENAME(var Message: TMessage); message WM_CHANGENAME; procedure WMSTATCLASS(var Message: TMessage); message WM_STATCLASS; procedure WMSTATSTATUS(var Message: TMessage); message WM_STATSTATUS; procedure WMSTATEDU(var Message: TMessage); message WM_STATEDU; procedure WMSTATENROLL(var Message: TMessage); message WM_STATENROLL; procedure WMStatGraduate(var Message: TMessage); message WM_STATGRADUATE;
procedure WMBURINFO(var Message: TMessage); message WM_BURINFO; end;

implementation
uses untSignNewStu, untSignSchInfo, untSignStatClass, untSignStatEdu, untSignStatEnroll, untSignStatStatus, untSignSchLib, untSignBurInfo, untSignMove, untSignStatGraduate, untSignAStuInfo;
{**********************************TMsgDisp ******************************}{constructor TMsgDisp.Create();begin //fMsgList := TObjectList.Create;end;
destructor TMsgDisp.Destroy;begin fMsgList.Free; inherited;end; }
{procedure TMsgDisp.RegisterMsg(Message: integer; MsgEvent: TMsgEvent);begin //fMsgList.Add()end; }
/// <summary>/// 通知owner，审批完成/// </summary>procedure TMsgDisp.NotifySigned;begin if Assigned(owner) then SendMessage((Owner as TWinControl).Handle,WM_MSGSIGNED,0,0);end;
procedure TMsgDisp.SignMsg(TfrmClass: TfrmSignBaseClass; Message: TMessage);begin frmSign := TfrmClass.Create(nil); with frmSign do begin try MsgID := Message.lParam; SenderCode := pstring(Message.wparam)^; if ShowModal = mrOk then NotifySigned; //通知审批完成 finally Free; end; end;
end;
procedure TMsgDisp.WMCHANGENAME(var Message: TMessage);begin
end;
procedure TMsgDisp.WMNewStu(var Message: TMessage);begin SignMsg(TfrmSignNewStu,Message);end;
procedure TMsgDisp.WMSchInfo(var Message: TMessage);begin SignMsg(TfrmSignSchInfo,Message);end;
procedure TMsgDisp.WMSCHLIB(var Message: TMessage);begin SignMsg(TfrmSignSchLib,Message);end;
procedure TMsgDisp.WMBURINFO(var Message: TMessage);begin SignMsg(TfrmSignBurInfo,Message);end;
procedure TMsgDisp.WMSTATCLASS(var Message: TMessage);begin SignMsg(TfrmSignStatClass,Message);end;
procedure TMsgDisp.WMSTATEDU(var Message: TMessage);begin SignMsg(TfrmSignStatEdu,Message);end;
procedure TMsgDisp.WMSTATENROLL(var Message: TMessage);begin SignMsg(TfrmSignStatEnroll,Message);end;
procedure TMsgDisp.WMStatGraduate(var Message: TMessage);begin signMsg(TfrmSignStatGraduate,Message);end;
procedure TMsgDisp.WMSTATSTATUS(var Message: TMessage);begin SignMsg(TfrmSignStatStatus,Message);end;
procedure TMsgDisp.WMStuMove(var Message: TMessage);begin SignMsg(TfrmSignMove,Message);end;
procedure TMsgDisp.WMEduInfo(var Message: TMessage);begin SignMsg(TfrmSignAStuInfo,Message);end;
end.
具体的审批窗体全部从一个窗体派生：