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我正在研究 TLogger 类，它将我的应用程序日志记录到文件中......

我必须将日志从文件获取到 TMemo： 1. 将 TMemo 分配给 TLogger 类，然后将 True 分配给 DisplayInMemo 属性，然后调用 GetLogFromFile(); 2.调用GetLogsFromFile()；然后 Self.Memo1.Text := TLogger.LogsResult;

下面...注释的解决方案工作正常...未注释的解决方案仅每 2 次单击按钮 4 有效

procedure TForm1.Button4Click(Sender: TObject);   // get log.file to memo
begin
  // automatic forwarding logs from File to TMemo - it works!
  //logger.DisplayMemo := Self.Memo1;
  //logger.DisplayInMemo := True;
  //logger.GetLogsFromFile();

  // tested - half-automatic method of formwarding logs to TMemo - works every 2 clicks :(
  logger.DisplayInMemo := False;
  logger.GetLogsFromFile();
  Self.Memo1.Text := logger.LogsResult;
end;

整个 TLogger 实现：

unit Logger;

interface

uses
  System.IOUtils, System.TypInfo, System.SysUtils, FMX.Forms, FMX.Dialogs, System.Classes, FMX.Graphics, FMX.ExtCtrls, LoggerThread, FMX.Memo;

type

  TLogger = class
  private
    FileName : String;                // name of file to log
    FilePath : String;                // path to app / log-file

    LStringResult : String;           // result of thread log.file reading
    LLoggerMemo : TMemo;              // copy of memo - place where GetLogsFromFile put results

    LDisplayInMemo : Boolean;         // bool - if True  GetLogsFromFile puts results to DisplayMemo, otherwise waiting in LogsResult
    NewLoggerThread : TLoggerThread;  // thread object - created in Create()

    procedure GetLogsFromFileThreadTerminateHandler(sender: TObject);

  public
    constructor Create(); overload;                     // open or create 'development.log'
    constructor Create(LogFileName : String); overload; // open or create LogFileName for logging
    destructor Destroy(); overload;                     // cleaner of TLogger object
    // main procedures
    procedure Log(LogString : String);                  // add line to log file
    procedure GetLogsFromFile();                        // get all logs from log file to string
    // settings, reading results,
    property DisplayInMemo : Boolean read LDisplayInMemo write LDisplayInMemo; //bool - if True  GetLogsFromFile puts results to DisplayMemo, otherwise waiting in LogsResult
    property LogsResult : String read LStringResult write LStringResult;       //string results after Getters from TLogger usage
    property DisplayMemo : TMemo read LLoggerMemo write LLoggerMemo;           // sets TMemo where results will be put if DisplayInMemo set to True
  end;

implementation

  constructor TLogger.Create();
  begin
    {$IFDEF Android}
      FilePath := TPath.GetDownloadsPath + System.SysUtils.PathDelim;
    {$ELSE}
      FilePath := ExtractFilePath(ParamStr(0));
    {$ENDIF}
    FileName := 'development.log';
    LDisplayInMemo := False;
    // inherited
    inherited Create;
  end;

  constructor TLogger.Create(LogFileName : String);
  begin
    {$IFDEF Android}
      FilePath := TPath.GetDownloadsPath + System.SysUtils.PathDelim;
      //TPath.Combine(TPath.GetDocumentsPath,'test.txt');  // to have / \ auto-change
    {$ELSE}
      FilePath := ExtractFilePath(ParamStr(0));
    {$ENDIF}
    FileName := LogFileName;
    LDisplayInMemo := False;
    // inherited
    inherited Create;
  end;

  destructor TLogger.Destroy();
  begin
    inherited Destroy;
  end;

  // adds a sigle line to log file with date time
  procedure TLogger.Log(LogString : String);
  begin
    NewLoggerThread :=  TLoggerThread.Create(True);
    NewLoggerThread.FreeOnTerminate := True;
    NewLoggerThread.Log := LogString;                                    //log to write - date time then added in execute
    NewLoggerThread.LoggerInstruction := TLoggerInstruction.liLogToFile; //set instuction for thread - LogToFile
    NewLoggerThread.FileName := FileName;  //file to write
    NewLoggerThread.FilePath := FilePath;  //path to file

    try
      NewLoggerThread.Start;
    except
      NewLoggerThread.Free();
    end;

  end;

  // results String with LogFile content
  procedure TLogger.GetLogsFromFile();
  begin
    NewLoggerThread :=  TLoggerThread.Create(True);
    NewLoggerThread.FreeOnTerminate := True;
    NewLoggerThread.OnTerminate := GetLogsFromFileThreadTerminateHandler;
    NewLoggerThread.FileName := FileName;  //file to write
    NewLoggerThread.FilePath := FilePath;  //path to file
    NewLoggerThread.LoggerInstruction := TLoggerInstruction.liGetLogsFromFile; //set instuction for thread - GetLogFromFile

    try
      NewLoggerThread.Start;
    except
      NewLoggerThread.Free();
    end;

  end;

  procedure TLogger.GetLogsFromFileThreadTerminateHandler(sender: TObject);
  begin
    LStringResult := (Sender as TLoggerThread).StringResult;
    if LDisplayInMemo then
        LLoggerMemo.Text := (Sender as TLoggerThread).StringResult;
  end;

end.

正如您所看到的，唯一的区别在于 LDisplayInMemo：如果是 True TMemo 会填充日志......什么时候是 False 我需要在按钮 4 上单击 2 次才能在 TMemo 中获得结果......

  procedure TLogger.GetLogsFromFileThreadTerminateHandler(sender: TObject);
  begin
    LStringResult := (Sender as TLoggerThread).StringResult;
    if LDisplayInMemo then
        LLoggerMemo.Text := (Sender as TLoggerThread).StringResult;
  end;

有任何想法吗？老实说，我不知道这两种解决方案工作不同的原因是什么:(我也在 Self.Memo1.Text := logger.LogsResult; 之后尝试了 ProcessMessages

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1 回答 1

2

以下代码仅在您第二次单击按钮时才起作用的原因是您实际获取日志信息的代码在另一个线程中运行......它是异步的！

logger.DisplayInMemo := False;
logger.GetLogsFromFile();
Self.Memo1.Text := logger.LogsResult; //This line runs AT THE SAME TIME you're getting logs!

注意：您在从 LoggerThread 获取值logger.LogsResult 之前读取 的值。

当您第二次单击该按钮时，线程已完成运行（第一次），您现在可以读取一个值。

您的评论部分有效的原因是您仅在线程终止时分配备忘录文本 - 即完成工作。

于 2014-02-06T18:41:39.180 回答