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這將是一個漫長的問題，但請耐心等待。我正在嘗試爲我們的應用程序創建一個Logging組件，該組件可以擴展到插件新的日誌記錄框架（NLog，Log4Net ec）。現在我知道我們已經有了Ben Foster編寫的Common.Logging外觀，但我想嘗試更多的自定義內容。在我們的例子中，主要的要求之一就是我們需要一個使用日誌框架（在這種情況下爲NLog）將各個參數/值記錄到數據庫的自定義機制。所以我有一個簡單的日誌接口：如何使用Unity爲LogManager（NLog）獲取指定的記錄器
/// <summary>
/// Interface for implementing a Logger Provider.
/// </summary>
public interface ILogger
{
/// <summary>
/// Logs an Info level diagnostics message.
/// </summary>
/// <param name="logInfo">The Log Info object.</param>
void Info(LogInfo logInfo);
/// <summary>
/// Logs a Warn level diagnostics message.
/// </summary>
/// <param name="logInfo">The Log Info object.</param>
void Warn(LogInfo logInfo);
/// <summary>
/// Logs a Debug level diagnostics message.
/// </summary>
/// <param name="logInfo">The Log Info object.</param>
void Debug(LogInfo logInfo);
/// <summary>
/// Logs an Error level diagnostics message.
/// </summary>
/// <param name="logInfo">The Log Info object.</param>
void Error(LogInfo logInfo);
/// <summary>
/// Logs an Fatal level diagnostics message.
/// </summary>
/// <param name="logInfo">The Log Info object.</param>
void Fatal(LogInfo logInfo);
}
LogInfo對象包含所有必要的日誌信息。我有一個實現接口的抽象類：
public abstract class NLogLoggerBase : ILogger
{
....
}
這是sublcassed到：
public class NLogDatabaseLogger : NLogLoggerBase
{
public NLogDatabaseLogger(ILogUtility logUtility)
: base(logUtility)
{
//Make sure the custom target is registered for use BEFORE using it.
ConfigurationItemFactory.Default.Targets.RegisterDefinition("DatabaseLog", typeof(DatabaseLogTarget));
//initialize the _logger
_logger = LogManager.GetLogger("DatabaseLogger");
}
}
和
public class NLogFileLogger : NLogLoggerBase
{
....
}
數據庫記錄器使用自定義DatabaseTarget（從TargetWithLayout繼承了NLOG ）登錄到數據庫，同上文件記錄器。 NLog的基本設置在App.Config中有線連接：
<?xml version="1.0" encoding="utf-8" ?>
<configuration>
<configSections>
<section name="nlog" type="NLog.Config.ConfigSectionHandler, NLog" />
</configSections>
<nlog xmlns="http://www.nlog-project.org/schemas/NLog.xsd" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
autoReload="true" throwExceptions="false" internalLogFile="C:\Temp\nlog.txt" internalLogLevel="Info"
internalLogToConsole="false">
<targets async="true">
<target name="CustomDatabaseLog" xsi:type="DatabaseLog" />
<target name="CustomFileLog" xsi:type="File" />
</targets>
<rules>
<logger name="DatabaseLogger" minlevel="Info" writeTo="CustomDatabaseLog" />
<logger name="FileLogger" minlevel="Info" writeTo="CustomFileLog" />
</rules>
</nlog>
</configuration>
到目前爲止這麼好。我對每個記錄儀都進行了一些測試，並且他們可以很好地記錄到各自的目標。
然後我寫了一個記錄器工廠，這將返回正確實施ILogger接口的基礎上，記錄類型：
/// <summary>
/// Provides an interface for a factory which returns a logger component.
/// </summary>
public interface ILoggerFactory
{
/// <summary>
/// Creates an instance of logger component based on dependency registration key.
/// </summary>
/// <param name="loggerName">The dependency registration key.</param>
/// <returns>An Instance of logger component.</returns>
ILogger CreateLogger(string loggerName);
}
和實現：
/// <summary>
/// Implementation of ILoggerFactory interface.
/// </summary>
public class NLogLoggerFactory : ILoggerFactory
{
private readonly ILogger _nlogDatabaseLogger;
private readonly ILogger _nlogFileLogger;
public NLogLoggerFactory(ILogger nlogDatabaseLogger, ILogger nlogFileLogger)
{
if (nlogDatabaseLogger == null)
throw new ArgumentNullException("nlogDatabaseLogger");
if (nlogFileLogger == null)
throw new ArgumentNullException("nlogFileLogger");
_nlogDatabaseLogger = nlogDatabaseLogger;
_nlogFileLogger = nlogFileLogger;
}
/// <summary>
/// Creates an instance of logger component based on dependency registration key.
/// </summary>
/// <param name="loggerKey">The dependency registration key.</param>
/// <returns>An Instance of logger component.</returns>
public ILogger CreateLogger(string loggerKey)
{
if (loggerKey.Equals(DependencyRegistrationKeys.NLogDatabaseLoggerKey))
return _nlogDatabaseLogger;
if (loggerKey.Equals(DependencyRegistrationKeys.NLogFileLoggerKey))
return _nlogFileLogger;
throw new ArgumentException("Invalid loggerKey");
}
所以我去佈線這一切都與統一。這是快速的測試情況下，我懷孕了（我知道這需要重新分解，但它是用於說明目的）：
[Test]
public void Test_if_logger_factory_returns_correct_implementation()
{
var container = new UnityContainer();
container.RegisterType<ILogUtility, NLogUtility>();
container.RegisterType<ILogger, NLogDatabaseLogger>(DependencyRegistrationKeys.NLogDatabaseLoggerKey);
container.RegisterType<ILogger, NLogFileLogger>(DependencyRegistrationKeys.NLogFileLoggerKey);
container.RegisterType<ILoggerFactory, NLogLoggerFactory>(
new InjectionConstructor(
new ResolvedParameter<ILogger>(DependencyRegistrationKeys.NLogDatabaseLoggerKey),
new ResolvedParameter<ILogger>(DependencyRegistrationKeys.NLogFileLoggerKey)));
var loggerFactory = container.Resolve<ILoggerFactory>();
Assert.IsAssignableFrom<NLogLoggerFactory>(loggerFactory);
var logger = loggerFactory.CreateLogger(DependencyRegistrationKeys.NLogDatabaseLoggerKey);
Assert.IsNotNull(logger);
Assert.IsAssignableFrom<NLogDatabaseLogger>(logger);
}
一切都很好，直到我打了一行：
var loggerFactory = container.Resolve<ILoggerFactory>();
這似乎打NLogDatabaseLogger的構造符合市場預期，並與例外在這條線炸燬：
//initialize the _logger
_logger = LogManager.GetLogger("DatabaseLogger");
例外：
Required parameter 'FileName' on 'File Target[CustomFileLog_wrapped]' was not specified.
我的猜測是，Unity正在努力獲取NLog，以獲取命名記錄器實例。有沒有人遇到過這個？這是否有辦法解決這個問題？整整一個早晨，我都爲此感慨萬分，但沒有骰子。任何幫助將非常感激！
LogManager的代碼在哪裏？那是來自NLog嗎？因爲LogManager.GetLogger看起來像是一個靜態方法調用，所以我不認爲Unity是問題，NLogLoggerBase會是我認爲有問題的代碼的位置 –
確實，LogManager是由NLog公開的靜態類。我結束了將FileTarget代碼移動到app.config文件 – tranceporter