我在主窗口中有一个带有文本框的wpf应用程序，该文本框应该用于在用户运行长进程时显示日志记录信息。
<TextBox Grid.Row="1" Margin="10,10,10,10" AcceptsReturn="True" Name="txtLogging" TextWrapping="WrapWithOverflow"
Text="{Binding Path=LogText, Mode=TwoWay}" ScrollViewer.HorizontalScrollBarVisibility="Auto" ScrollViewer.VerticalScrollBarVisibility="Auto" />
public string LogText
{
get { return _logText; }
set
{
_logText = value;
OnPropertyChanged();
}
}
ui上的一个按钮启动一个至少需要30秒的过程，有时甚至会持续几个小时。不用说，在背景工作者上运行它是首选。问题是程序中的日志记录类是在UI线程上创建的，并且必须在工作人员执行期间访问，以使用当前正在发生的日志更新UI。
记录器看起来像这样;
using System;
using System.IO;
namespace BatchInvoice
{
public enum LoggingLevel
{
Verbose = 0,
Info = 1,
Warning = 2,
Error = 3
}
public sealed class Logger
{
string _logFile;
static Logger() { }
public bool LogToDataBase = false;
public bool LogToFile = true;
public bool LogToScreen = false;
private Logger()
{
//string filePath = Environment.GetFolderPath(Environment.SpecialFolder.Desktop);
string filePath = Directory.GetCurrentDirectory();
filePath = filePath + @"\LogFiles";
string extension = ".log";
if (!Directory.Exists(filePath))
{
Directory.CreateDirectory(filePath);
}
/*string currentDir = Environment.CurrentDirectory;
DirectoryInfo directory = new DirectoryInfo(currentDir);
string fullDirectory = directory.FullName;*/
string date = (DateTime.Now).ToString("yyyyMMddHHmmss");
_logFile = filePath + "\\" + date + extension;
minimumLoggingLevel = LoggingLevel.Info;
}
private LoggingLevel minimumLoggingLevel;
public static void SetMinimumLoggingLevel(LoggingLevel minimum)
{
Instance.minimumLoggingLevel = minimum;
}
public static LoggingLevel GetMinimumLoggingLevel()
{
return Instance.minimumLoggingLevel;
}
private static readonly Logger instance = new Logger();
public static Logger Instance
{
get
{
return instance;
}
}
public static void Write(string content)
{
using (StreamWriter fileWriter = File.AppendText(Instance._logFile))
{
fileWriter.WriteLine(content);
}
}
public static void Write(string content, LoggingLevel warningLevel)
{
if (Instance.minimumLoggingLevel <= warningLevel)
{
if (Instance.LogToFile)
{
using (StreamWriter fileWriter = File.AppendText(Instance._logFile))
{
fileWriter.WriteLine(warningLevel.ToString() + ": " + content);
}
}
if (Instance.LogToScreen)
ScreenLogging.Write(content, warningLevel);
if (Instance.LogToDataBase)
{
//enter database loggign code here.
}
}
}
}
}
using System.Windows;
using System.Windows.Controls;
namespace BatchInvoice
{
public class ScreenLogging
{
private static ScreenLogging _instance;
private ScreenLogging() { }
public static ScreenLogging Instance
{
get
{
if(_instance == null)
{
_instance = new ScreenLogging();
}
return _instance;
}
}
private TextBox _target;
public static void SetTarget(TextBox target)
{
Instance._target = target;
}
public static void Write(string content, LoggingLevel warningLevel)
{
//MessageBox.Show(content, warningLevel.ToString());
Instance._target.AppendText(warningLevel.ToString() + ": " + content + "\n");
}
}
}
（是的，有一个原因是将屏幕记录分成不同的类，但我真的希望我不必改变它）我该怎样做才能调用这个日志类来反映在UI上在后台工作人员？我应该更改LogText属性以从外部文件或沿着这些行的内容读取吗？目前我没有实施后台工作程序，因此日志记录仅在任务完成后显示，但我需要能够在其运行时监视其进度。当我尝试将它放入后台工作程序时，当它遇到试图访问记录器的一行代码时会出错。
答案 0 :(得分：3)
由于您尝试从另一个线程更新UI，因此必须以特殊方式执行此操作，其中必须同步线程以在它们之间传输数据。换句话说，就像BackgroundWorker需要暂停来更新UI一样。可以使用BackgroundWorker的ProgressChanged事件和ReportProgress方法来完成。这是一个简单的例子：
private void Window_Loaded(object sender, RoutedEventArgs e)
{
// I guess this is how you are using your logger, right?
ScreenLogging.SetTarget(this.txtLogging);
BackgroundWorker worker = new BackgroundWorker();
// Your classic event to do the background work...
worker.DoWork += Worker_DoWork;
// Here you can sender messages to UI.
worker.ProgressChanged += Worker_ProgressChanged;
// Don't forget to turn this property to true.
worker.WorkerReportsProgress = true;
worker.RunWorkerAsync();
}
private void Worker_DoWork(object sender, DoWorkEventArgs e)
{
var worker = sender as BackgroundWorker;
Thread.Sleep(3000);
// ReportProgress sends two values to the ProgressChanged method, for the
// ProgressChangedEventArgs object. The first one is the percentage of the
// work, and the second one can be any object that you need to pass to UI.
// In a simple example, I am passing my log message and just putting
// any random value at progress, since it does not matter here.
worker.ReportProgress(0, "Test!");
}
private void Worker_ProgressChanged(object sender, ProgressChangedEventArgs e)
{
// Here you get your UserState object, wich is my string message passed on
// with the ReportProgress method above.
var message = e.UserState as string;
// Then you call your log as always. Simple, right?
ScreenLogging.Write(message, LoggingLevel.Info);
}
答案 1 :(得分：1)
由于您的问题似乎没有重写所有日志调用，我将通过更改ScreenLogging.Write方法发布另一种方法。我希望这对您有用，因为您不需要更改对Logger.Write方法的调用。
public class ScreenLogging
{
private static ScreenLogging _instance;
private ScreenLogging() { }
public static ScreenLogging Instance
{
get
{
if (_instance == null)
{
_instance = new ScreenLogging();
}
return _instance;
}
}
private TextBox _target;
public static void SetTarget(TextBox target)
{
Instance._target = target;
}
public static void Write(string content, LoggingLevel warningLevel)
{
var appendTextAction = new Action(() =>
{
var text = warningLevel.ToString() + ": " + content + "\n";
Instance._target.AppendText(text);
});
// Only the thread that the Dispatcher was created on may access the
// DispatcherObject directly. To access a DispatcherObject from a
// thread other than the thread the DispatcherObject was created on,
// call Invoke and BeginInvoke on the Dispatcher the DispatcherObject
// is associated with.
// You can set the priority to Background, so you guarantee that your
// key operations will be processed first, and the screen updating
// operations will happen only after those operations are done.
Instance._target.Dispatcher.Invoke(appendTextAction,
DispatcherPriority.Background);
}
}