使用Delphi写入Windows事件日志

Question

我的Delphi应用程序如何轻松写入Windows事件日志？

TEventLogger和ReportEvent有什么区别？我如何使用ReportEvent函数？

Answer 1

如果您正在编写Windows服务并需要写入本地计算机的Windows事件日志,则可以调用 TService.这里提到的LogMessage.

//TMyTestService = class(TService)

procedure TMyTestService.ServiceStart(Sender: TService; var Started: Boolean);
begin
  LogMessage('This is an error.');
  LogMessage('This is another error.', EVENTLOG_ERROR_TYPE);
  LogMessage('This is information.', EVENTLOG_INFORMATION_TYPE);
  LogMessage('This is a warning.', EVENTLOG_WARNING_TYPE);
end;

对于任何其他类型的应用程序,您可以使用SvcMgr.TEventLogger 无证的TService辅助类写的本地计算机的Windows事件日志中提到这里,这里和这里.

uses
  SvcMgr;

procedure TForm1.EventLoggerExampleButtonClick(Sender: TObject);
begin
  with TEventLogger.Create('My Test App Name') do
  begin
    try
      LogMessage('This is an error.');
      LogMessage('This is another error.', EVENTLOG_ERROR_TYPE);
      LogMessage('This is information.', EVENTLOG_INFORMATION_TYPE);
      LogMessage('This is a warning.', EVENTLOG_WARNING_TYPE);
    finally
      Free;
    end;
  end;
end;

您还可以使用此处和此处提到的Windows API ReportEvent函数.

我已经创建了一个简单的类来使它更容易,它可以在GitHub上获得.

//----------------- EXAMPLE USAGE: ---------------------------------

uses
  EventLog;

procedure TForm1.EventLogExampleButtonClick(Sender: TObject);
begin
  TEventLog.Source := 'My Test App Name';

  TEventLog.WriteError('This is an error.');
  TEventLog.WriteInfo('This is information.');
  TEventLog.WriteWarning('This is a warning.');
end;

//------------------------------------------------------------------

unit EventLog;

interface

type
  TEventLog = class
  private
    class procedure CheckEventLogHandle;
    class procedure Write(AEntryType: Word; AEventId: Cardinal; AMessage: string); static;
  public
    class var Source: string;
    class destructor Destroy;

    class procedure WriteInfo(AMessage: string); static;
    class procedure WriteWarning(AMessage: string); static;
    class procedure WriteError(AMessage: string); static;

    class procedure AddEventSourceToRegistry; static;
  end;

threadvar EventLogHandle: THandle;

implementation

uses Windows, Registry, SysUtils;

class destructor TEventLog.Destroy;
begin
  if EventLogHandle > 0 then
  begin
    DeregisterEventSource(EventLogHandle);
  end;
end;

class procedure TEventLog.WriteInfo(AMessage: string);
begin
  Write(EVENTLOG_INFORMATION_TYPE, 2, AMessage);
end;

class procedure TEventLog.WriteWarning(AMessage: string);
begin
  Write(EVENTLOG_WARNING_TYPE, 3, AMessage);
end;

class procedure TEventLog.WriteError(AMessage: string);
begin
  Write(EVENTLOG_ERROR_TYPE, 4, AMessage);
end;

class procedure TEventLog.CheckEventLogHandle;
begin
  if EventLogHandle = 0 then
  begin
   EventLogHandle := RegisterEventSource(nil, PChar(Source));
  end;
  if EventLogHandle <= 0 then
  begin
    raise Exception.Create('Could not obtain Event Log handle.');
  end;
end;

class procedure TEventLog.Write(AEntryType: Word; AEventId: Cardinal; AMessage: string);
begin
  CheckEventLogHandle;
  ReportEvent(EventLogHandle, AEntryType, 0, AEventId, nil, 1, 0, @AMessage, nil);
end;

// This requires admin rights. Typically called once-off during the application's installation
class procedure TEventLog.AddEventSourceToRegistry;
var
  reg: TRegistry;
begin
  reg := TRegistry.Create;
  try
    reg.RootKey := HKEY_LOCAL_MACHINE;
    if reg.OpenKey('\SYSTEM\CurrentControlSet\Services\Eventlog\Application\' + Source, True) then
    begin
      reg.WriteString('EventMessageFile', ParamStr(0)); // The application exe's path
      reg.WriteInteger('TypesSupported', 7);
      reg.CloseKey;
    end
    else
    begin
      raise Exception.Create('Error updating the registry. This action requires administrative rights.');
    end;
  finally
    reg.Free;
  end;
end;

initialization

TEventLog.Source := 'My Application Name';

end.

ReportEvent支持将日志条目写入本地或远程计算机的事件日志.有关远程示例,请参阅 John Kaster的EDN文章.

请注意,您还必须创建一个消息文件并注册您的事件源,否则所有日志消息都将以这样的方式开头:

无法找到源xxxx的事件ID xxx的描述.引发此事件的组件未安装在本地计算机上,或者安装已损坏.您可以在本地计算机上安装或修复该组件.

如果事件源自另一台计算机,则必须随事件一起保存显示信息.

活动中包含以下信息:

1,有关如何创建消息文件的更多信息,请参阅Finn Tolderlund的教程或Michael Hex的文章, 或者您可以使用GitHub项目中包含的现有MC和RES文件.

2,通过在DPR文件中包含MessageFile.res,将RES文件嵌入到您的应用程序中.或者,您可以为消息创建一个dll.

program MyTestApp;

uses
  Forms,
  FormMain in 'FormMain.pas' {MainForm},
  EventLog in 'EventLog.pas';

{$R *.res}
{$R MessageFile\MessageFile.res}

begin
  Application.Initialize;

3,一次性注册需要管理员权限写入注册表,因此我们通常在应用程序的安装过程中完成.

//For example
AddEventSourceToRegistry('My Application Name', ParamStr(0));
//or
AddEventSourceToRegistry('My Application Name', 'C:\Program Files\MyApp\Messages.dll');

//--------------------------------------------------

procedure AddEventSourceToRegistry(ASource, AFilename: string);
var
  reg: TRegistry;
begin
  reg := TRegistry.Create;
  try
    reg.RootKey := HKEY_LOCAL_MACHINE;
    if reg.OpenKey('\SYSTEM\CurrentControlSet\Services\Eventlog\Application\' + ASource, True) then
    begin
      reg.WriteString('EventMessageFile', AFilename);
      reg.WriteInteger('TypesSupported', 7);
      reg.CloseKey;
    end
    else
    begin
      raise Exception.Create('Error updating the registry. This action requires administrative rights.');
    end;
  finally
    reg.Free;
  end;
end;

如果您需要Windows事件日志等日志记录的要求,您还可以使用日志框架,如log4d和的TraceTool

如果要写入Delphi IDE中的"事件日志"窗口,请在此处查看.