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

Question

在设置我的 TCP 客户端/服务器系统时，我对 TIdServerContext 进行了子类化以添加索引标志，但似乎没有 OnWork 事件。我需要重置计时器，例如在上传/下载大文件时，许多 Indy 组件都有一个专门用于此目的的 OnWork 事件，但我找不到用于 的计时器根据其他帖子，TIdServerContext 或 TIdTCPServer 以及 TIdTCPServer.OnStatus 事件似乎未实现。

以下是我实现 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... 事件位于 TIdComponent 类中，而 TIdServerContext 并非派生自该类。但是，TIdTCPConnection 和 TIdIOHandler 可以。 TIdContext 具有公共(public) Connection 属性，因此在服务器的事件(OnConnect、OnExecute 等)中，您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，在不使用 Tag 的情况下将 AContext 传递给 WorkHandler 的另一种方法:

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;

处理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首先触发的 (Connect|OnExecute) 事件:

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，如果您只需要按需举办事件:

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;