c# - 如何使用 Unity 为 LogManager (NLog) 获取命名记录器

Question

这将是一个冗长的问题，但请耐心等待。我正在尝试为我们的应用程序创建一个日志记录组件，它可以扩展为插入新的日志记录框架(NLog、Log4Net ec)。现在我知道我们已经有了由 Ben Foster 编写的 Common.Logging 门面，但我想尝试一些更定制的东西。在我们的案例中，一个主要要求是我们需要一种自定义机制，使用日志记录框架(在本例中为 NLog)将各个参数/值记录到数据库中。所以我有一个简单的日志记录界面:

/// <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 对象包含所有必要的日志记录信息。我有一个实现接口(interface)的抽象类:

public abstract class NLogLoggerBase : ILogger
{
     ....
}

它被子类化为:

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
{
   ....
}

数据库记录器使用自定义的 DatabaseTarget(继承自 NLog 中的 TargetWithLayout)来登录数据库，文件记录器也是如此。 NLog 的基本设置在 App.Config 中:

<?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>

到目前为止一切顺利。我对每个记录器进行了一些测试，它们可以很好地记录到各自的目标。

然后我写了一个 Logger 工厂，它将根据记录器类型返回 ILogger 接口(interface)的正确实现:

/// <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);
}

和实现:

/// <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");
    }

所以我开始使用 Unity 将其全部连接起来。这是我编写的快速测试用例(我知道它需要重构，但它只是为了说明目的):

    [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);
    }

一切正常，直到我到达终点:

var loggerFactory = container.Resolve<ILoggerFactory>();

这似乎按预期命中了 NLogDatabaseLogger 的构造函数，并在该行上爆炸并出现异常:

//initialize the _logger
_logger = LogManager.GetLogger("DatabaseLogger");

异常(exception):

Required parameter 'FileName' on 'File Target[CustomFileLog_wrapped]' was not specified.

我的猜测是 Unity 正在努力获取 NLog，以获取命名记录器实例。有没有人遇到过这个？有没有办法解决？我整个上午都在为此苦思冥想，但没有骰子。非常感谢任何帮助!

Answer 1

查看这个问题和我的回答。

How to Inject Log4Net ILog implementations using Unity 2.0

问题是关于使用 unity 解析命名 log4net 记录器，但我认为您应该能够将相同的过程应用于 NLog 和 unity。

该问题的 OP 写了一个 nice blog post描述了他为使它起作用所经历的确切过程。从他的博客文章中，这些是所需的步骤(假设有一些统一知识):

在 Unity 中实现它需要三个步骤。

1. 创建构建跟踪扩展
2. 创建记录器创建扩展
3. 将扩展连接到 Unity

祝你好运!