Entlib 6 记录器实例化中的错误

Question

我在为企业库 6.0 日志记录组件设置日志编写器时遇到异常。第一次出现日志记录时，它就会成功。但是对于连续调用，它会抛出异常：The LogWriter is already set.我尝试检查 Logger.Writer 是否不为空。但这首先失败了，除了我应该使用 Logger.SetLogWriter 设置编写器。

这是我的代码：

if (Logger.Writer == null)  // fails on first call
{
    IConfigurationSource configurationSource = ConfigurationSourceFactory.Create();
    LogWriterFactory logWriterFactory = new LogWriterFactory(configurationSource);
    Logger.SetLogWriter(logWriterFactory.Create()); // fails on subsequent calls.
}

Answer 1

试试这个：

IConfigurationSource configurationSource = ConfigurationSourceFactory.Create();
LogWriterFactory logWriterFactory = new LogWriterFactory(configurationSource);
Logger.SetLogWriter(logWriterFactory.Create(), false);

Answer 2

我在使用 6.0 版本时也遇到了同样的问题。我通过创建自己的静态记录器类并在构造函数中初始化 SetLogWriter（） 来解决这个问题。下面是代码：

using System;
using ms = Microsoft.Practices.EnterpriseLibrary.Logging;
using Microsoft.Practices.EnterpriseLibrary.Common.Configuration;
namespace LoggingService
{
    public static class Logger
    {
        static Logger()
        {
            try
            {
                IConfigurationSource configurationSource = ConfigurationSourceFactory.Create();
                ms.LogWriterFactory logWriterFactory = new ms.LogWriterFactory(configurationSource);
                ms.Logger.SetLogWriter(new ms.LogWriterFactory().Create());
            }
            catch (Exception)
            {
            }
        }
        /// <summary>
        /// Writes exception details to the log using Enterprise Library
        /// </summary>
        /// <param name="ex"></param>
        public static void Log(Exception ex)
        {
// can be changed as per your requirement for the event/priority and the category
            ms.Logger.Write(ex, "ErrorsWarnings", 1, 1, System.Diagnostics.TraceEventType.Error);
        }
        /// <summary>
        /// Writes Information message to the log using Enterprise Library
        /// </summary>
        /// <param name="infoMsg"></param>
        public static void Log(string infoMsg)
        {
            ms.Logger.Write(infoMsg);
        }
    }
}

并且简单地像

Logger.Log(ex);
//or
Logger.Log("Your message");

Answer 3

答案是使用静态变量，以便只获取一个日志编写器实例

这样做：

public class BaseController : Controller
{
    private static ExceptionManager _exceptionManager;
    private static LogWriter _logWriter;
    public ExceptionManager ExceptionManager
    {
        get
        {
            IUnityContainer container = new UnityContainer();
            try
            {
                if (_exceptionManager == null)
                {
                    IConfigurationSource configurationSource = ConfigurationSourceFactory.Create();
                    ExceptionPolicyFactory exceptionFactory = new ExceptionPolicyFactory(configurationSource);
                    if (configurationSource.GetSection(LoggingSettings.SectionName) != null)
                    {
                        LogWriterFactory logWriterFactory = new LogWriterFactory(configurationSource);
                        Logger.SetLogWriter(logWriterFactory.Create());
                    }
                    container.RegisterInstance<ExceptionManager>(exceptionFactory.CreateManager());
                    _exceptionManager = container.Resolve<ExceptionManager>();
                    return _exceptionManager;
                }
                else
                {
                    return _exceptionManager;
                }
            }
            finally
            {
                ((IDisposable)container).Dispose();
            }
        }
        set
        {
            _exceptionManager = value;
        }
    }
    /// <summary>
    /// Used to log entries in the log file
    /// </summary>
    public LogWriter LogWriter
    {
        get
        {
            IUnityContainer container = new UnityContainer();
            try
            {
                if (_logWriter == null)
                {
                    IConfigurationSource configurationSource = ConfigurationSourceFactory.Create();
                    LogWriterFactory logWriterFactory = new LogWriterFactory(configurationSource);
                    Logger.SetLogWriter(logWriterFactory.Create());
                    // Singleton
                    container.RegisterInstance<LogWriter>(logWriterFactory.Create());
                    _logWriter = container.Resolve<LogWriter>();
                    return _logWriter;
                }
                else
                    return _logWriter;
            }
            finally
            {
                ((IDisposable)container).Dispose();
            }
        }
        set
        {
            _logWriter = value;
        }
    }

    protected override void OnActionExecuting(ActionExecutingContext filterContext)
    {
        Thread.CurrentThread.CurrentUICulture = new CultureInfo("es");
        Thread.CurrentThread.CurrentCulture = new CultureInfo("es");
        if (Session.Count == 0)
        {
            filterContext.Result = new RedirectToRouteResult(new RouteValueDictionary { { "controller", "Account" }, { "action", "Login" } });
        }
    }
    protected override void OnException(ExceptionContext filterContext)
    {
        this.ExceptionManager.HandleException(filterContext.Exception, "AllExceptionsPolicy");
        //Show basic Error view
        filterContext.ExceptionHandled = true;
        //Clear any data in the model as it wont be needed
        ViewData.Model = null;
        //Show basic Error view
        View("Error").ExecuteResult(this.ControllerContext);
    }
}

Answer 4

您是否检查过您的web.config（如果是 asp.net）或app.config（如果是控制台或Windows应用程序）中没有任何LogWriter设置。

另请参阅如何在此线程中使用 LogWriter （Microsoft.Practices.EnterpriseLibrary.Logging.dll）

如何在 EntLib 日志应用块中为跟踪侦听器设置和使用多个格式化程序

Answer 5

在早期版本中，我们使用

var logWriter = EnterpriseLibraryContainer.Current.GetInstance<LogWriter>();

EnterpriseLibraryContainer 返回相同的实例。

但是在EL 6.0中，LibraryContainer被丢弃了。但是，记录器似乎只包含一个具有一次性初始化的编写器。

我在静态变量的帮助下解决了这个问题，以检查编写器是否已初始化。 或者，它可以通过单例或静态实体来完成。

Answer 6

Logger.SetLogWriter(logWriterFactory.Create(), false);

默认情况下，throwIfSet标志设置为 true，如果已设置日志编写器，则会引发异常。