delphi - 使用Delphi和Indy 10.6，我找不到TIdServerContext的OnWork

Question

在设置TCP Client / Server系统时，我将TIdServerContext子类化以添加索引标志，但是似乎没有OnWork事件。我需要重置一个计时器，比如说在上传/下载大文件时，很多Indy组件都有一个OnWork事件用于此操作，但我找不到用于TIdServerContext或TIdTCPServer的事件，根据其他帖子，TIdTCPServer.OnStatus事件似乎未实现。

这是我实现TIdServerContext的方法：

TUserContext = Class(TIdServerContext)
Protected
  FUserID: Integer;
Public
  Property UserID: Integer Read FUserID Write FUserID Default 0;
End;

Procedure FormCreate(Sender: TObject);
Begin
  Server.ContextClass := TUserContext;
End;

Procedure ServerExecute(AContext: TIdContext);
Var
  I: Integer;
Begin
  I := TUserContext(AContext).UserID;
  ...
End;

Answer 1

OnWork...事件在TIdComponent类中，而TIdServerContext并非此类来源。但是，TIdTCPConnection和TIdIOHandler可以。 TIdContext具有公共的Connection属性，因此在服务器的事件（OnConnect，OnExecute等）中，可以根据需要将处理程序分配给TIdConnection.OnWork...事件：

procedure TMyForm.ServerConnect(AContext: TIdContext);
begin
  AContext.Connection.Tag := NativeInt(AContext);
  AContext.Connection.OnWork := WorkHandler;
end;

procedure TMyForm.WorkHandler(ASender: TObject; AWorkMode: TWorkMode; AWorkCount: Int64);
var
  Ctx: TUserContext;
begin
  Ctx := TUserContext(TIdTCPConnection(ASender).Tag);
  // use Ctx members as needed...
end;

或者，另一种无需使用 AContext即可将 WorkHandler传递给 Tag的方法：

procedure TMyForm.ServerConnect(AContext: TIdContext);
var
  Handler: TWorkEvent;
begin
  Handler := WorkHandler;
  TMethod(Handler).Data := AContext;
  AContext.Connection.OnWork := Handler;
end;

procedure TMyForm.WorkHandler(ASender: TObject; AWorkMode: TWorkMode; AWorkCount: Int64);
var
  Ctx: TUserContext;
begin
  Ctx := TUserContext(Self);
  // use Ctx members as needed...
end;

解决此问题的另一种方法是重写 TIdServerContext构造函数，该构造函数接收 TIdTCPConnection对象作为参数。您可以使处理程序成为 TUserContext类本身的方法，并让其构造函数立即分配 OnWork...事件，而不是等待服务器的 On(Connect|OnExecute)事件首先触发：

type
  TUserContext = Class(TIdServerContext)
  protected
    FUserID: Integer;
    procedure WorkHandler(ASender: TObject; AWorkMode: TWorkMode; AWorkCount: Int64);
  public
    constructor Create(AConnection: TIdTCPConnection; AYarn: TIdYarn; AList: TIdContextThreadList = nil); override;
    property UserID: Integer read FUserID write FUserID;
  end;

constructor TUserContext.Create(AConnection: TIdTCPConnection; AYarn: TIdYarn; AList: TIdContextThreadList = nil);
begin
  inherited;
  AConnection.OnWork := WorkHandler;
end;

procedure TUserContext.WorkHandler(ASender: TObject; AWorkMode: TWorkMode; AWorkCount: Int64);
begin
  // use Self members as needed...
end;

或者，如果您只需要根据需要进行活动：

type
  TUserContext = Class(TIdServerContext)
  protected
    FUserID: Integer;
    procedure WorkHandler(ASender: TObject; AWorkMode: TWorkMode; AWorkCount: Int64);
  public
    procedure StartWorkTimer;
    procedure StopWorkTimer;
    property UserID: Integer read FUserID write FUserID;
  end;

procedure TUserContext.StartWorkTimer;
begin
  Connection.OnWork := WorkHandler;
end;

procedure TUserContext.StopWorkTimer;
begin
  Connection.OnWork := nil;
end;

procedure TMyForm.ServerExecute(AContext: TIdContext);
var
  Ctx: TUserContext;
begin
  Ctx := TUserContext(AContext);

  ...

  if (some condition) then
    Ctx.StartWorkTimer;

  ...

  if (some other condition) then
    Ctx.StopWorkTimer;

  ...
end;