該文章是系列文章 基於.NetCore和ABP框架如何讓Windows服務執行Quartz定時作業 的其中一篇。
比較流行的日志組件有以下四種，Topshelf都有相應的組件提供
本篇文章主要介紹log4net的使用。
配置log4net
在使用Topshelf創建Windows服務中提到了當我們調試的時候Console會打印出如下的類似日志
Configuration Result:
[Success] Name Demo.MyJob
[Success] Description Demo.MyJob Service
[Success] ServiceName Demo.MyJob
Topshelf v4.2.0.194, .NET Framework v4.0.30319.42000
The Demo.MyJob service is now running, press Control+C to exit.
該日志是如何打印出來的呢？
訪問Topshelf Github的源碼，在HostFactory.cs查看Run執行邏輯，日志打印是通過調用HostLogger.Get(Type type) 方法獲取了LogWriter，LogWriter是寫日志接口。查看HostLogger.cs，可以看到LogWriter的默認實現，該實現包含有三個類TraceHostLoggerConfigurator.cs 繼承接口HostLoggerConfigurator、TraceLogWriterFactory.cs 繼承接口LogWriterFactory、TraceLogWriter.cs 繼承接口LogWriter。
如果我們需要實現log4net的日志訪問，則需要實現三個類Log4NetLoggerConfigurator、Log4NetLoggerConfigurator、Log4NetLogWriter。我們可以自己實現，也可以使用Topshelf提供的實現，需要引用nuget包Topshelf.Log4Net。在Run執行邏輯添加UseLog4Net，如下所示。
public override void PostInitialize()
{
HostFactory.Run(configure =>
{
//定義服務描述
configure.SetDescription("Demo.MyJob Service");
configure.SetDisplayName("Demo.MyJob");
configure.SetServiceName("Demo.MyJob");
configure.RunAsLocalSystem();
//使用log4net記錄日志
configure.UseLog4Net("App.config");
//定義操作
configure.Service<MyJobService>(service =>
{
service.ConstructUsing(_ => new MyJobService());
service.WhenStarted(async _ => await _.StartAsync());
service.WhenStopped(async _ => await _.StopAsync());
service.WhenContinued(async _ => await _.ContinueAsync());
service.WhenPaused(async _ => await _.PauseAsync());
});
});
}
在上述代碼中可知，我們需要添加自己的配置文件，對log4net進行配置。注意：需將添加的配置文件的屬性配置為如果較新則復制。因為UseLog4Net關於加載配置文件的邏輯，是加載當前應用目錄下的指定名稱的文件。
更多關於log4net的配置請訪問：https://logging.apache.org/log4net/release/manual/configuration.html
未使用log4net打印日志時，打印出來的日志是黑底白字，我們可以通過log4net配置改變打印字體的顏色，使用ManagedColoredConsoleAppender,也可以通過RollingFileAppender在本地機器生成log日志文件。
<?xml version="1.0" encoding="utf-8" ?>
<configuration>
<log4net>
<appender name="ManagedColoredConsoleAppender" type="log4net.Appender.ManagedColoredConsoleAppender">
<mapping>
<level value="ERROR" />
<foreColor value="Red" />
</mapping>
<mapping>
<level value="Info" />
<foreColor value="Green" />
</mapping>
<mapping>
<level value="DEBUG" />
<foreColor value="Blue" />
</mapping>
<mapping>
<level value="WARN" />
<foreColor value="Yellow" />
</mapping>
<layout type="log4net.Layout.PatternLayout">
<conversionPattern value="%d{ABSOLUTE} [%thread] %-5p %c{1}:%L - %m%n" />
</layout>
<filter type="log4net.Filter.LevelRangeFilter">
<param name="LevelMin" value="DEBUG" />
<param name="LevelMax" value="Fatal" />
</filter>
</appender>
<appender name="RollingFile" type="log4net.Appender.RollingFileAppender">
<lockingModel type="log4net.Appender.FileAppender+MinimalLock" />
<file value=".\logs\" />
<datePattern value="'my-windows-service-'dd.MM.yyyy'.log'" />
<staticLogFileName value="false" />
<appendToFile value="true" />
<rollingStyle value="Composite" />
<maxSizeRollBackups value="10" />
<maximumFileSize value="5MB" />
<layout type="log4net.Layout.PatternLayout">
<conversionPattern value="%d [%t] %-5p %c - %m%n" />
</layout>
</appender>
<root>
<level value="DEBUG" />
<appender-ref ref="ManagedColoredConsoleAppender" />
<appender-ref ref="RollingFile" />
</root>
</log4net>
</configuration>
在配置文件中使用了<file value=".\logs\" />指定了文件生成相對路徑，該相對路徑應指向的是應用程序當前目錄下，該目錄下確實生成了日志文件，但是很不爽的是在C:\Windows\System32路徑下也生成了文件。怎么解決該問題？通過log4net屬性指定目錄。
修改<file type="log4net.Util.PatternString" value="%property{LogsDirectory}\logs\" />，並需要添加一行配置代碼log4net.GlobalContext.Properties["LogsDirectory"] = AppDomain.CurrentDomain.BaseDirectory;，如下所示。問題解決。
public override void PostInitialize()
{
log4net.GlobalContext.Properties["LogsDirectory"] = AppDomain.CurrentDomain.BaseDirectory;
HostFactory.Run(configure =>
{
//定義服務描述
configure.SetDescription("Demo.MyJob Service");
configure.SetDisplayName("Demo.MyJob");
configure.SetServiceName("Demo.MyJob");
configure.RunAsLocalSystem();
//使用log4net記錄日志
configure.UseLog4Net("App.config");
//定義操作
configure.Service<MyJobService>(service =>
{
service.ConstructUsing(_ => new MyJobService());
service.WhenStarted(async _ => await _.StartAsync());
service.WhenStopped(async _ => await _.StopAsync());
service.WhenContinued(async _ => await _.ContinueAsync());
service.WhenPaused(async _ => await _.PauseAsync());
});
});
}
關於Appenders的特別說明
官網上哪些平台可用的Appenders表格如下
| Appender | .NET Framework 1.0 | .NET Framework 1.1 | .NET Framework 2.0 | .NET Framework 3.5 | .NET Framework 4.0 | .NET Framework 4.5 | .NET Framework 3.5 Client Profile | .NET Framework 4.0 Client Profile | .NET Standard 1.3 | .NET CF 1.0 | .NET CF 2.0 | Mono | Shared Source CLI 1.0 | CLI 1.0 Compatible |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| AdoNetAppender | x | x | x | x | x | x | x | x | x | x | x | x | ||
| AnsiColorTerminalAppender | x | x | x | x | x | x | x | x | x | x | x | x | x | x |
| AspNetTraceAppender | x | x | x | x | x | x | x | x | ||||||
| BufferingForwardingAppender | x | x | x | x | x | x | x | x | x | x | x | x | x | x |
| ColoredConsoleAppender | x | x | x | x | x | x | x | x | ||||||
| ConsoleAppender | x | x | x | x | x | x | x | x | x | x | x | x | x | x |
| DebugAppender | x | x | x | x | x | x | x | x | x | x | x | x | x | x |
| EventLogAppender | x | x | x | x | x | x | x | x | x | x | ||||
| FileAppender | x | x | x | x | x | x | x | x | x | x | x | x | x | x |
| ForwardingAppender | x | x | x | x | x | x | x | x | x | x | x | x | x | x |
| LocalSyslogAppender | x | x | x | x | x | x | x | x | x | x | x | |||
| ManagedColoredConsoleAppender | x | x | x | x | x | x | x | x | ||||||
| MemoryAppender | x | x | x | x | x | x | x | x | x | x | x | x | x | x |
| NetSendAppender | x | x | x | x | x | x | x | x | ||||||
| OutputDebugStringAppender | x | x | x | x | x | x | x | x | x | x | x | |||
| RemoteSyslogAppender | x | x | x | x | x | x | x | x | x | x | x | x | x | x |
| RemotingAppender | x | x | x | x | x | x | x | x | x | x | x | |||
| RollingFileAppender | x | x | x | x | x | x | x | x | x | x | x | x | x | x |
| SmtpAppender | x | x | x | x | x | x | x | x | x | x | ||||
| SmtpPickupDirAppender | x | x | x | x | x | x | x | x | x | x | x | x | x | x |
| TelnetAppender | x | x | x | x | x | x | x | x | x | x | x | x | x | x |
| TraceAppender | x | x | x | x | x | x | x | x | x | x | x | x | x | x |
| UdpAppender | x | x | x | x | x | x | x | x | x | x | x | x | x | x |
由表格得知 ManagedColoredConsoleAppender 不支持 .NET Standard 1.3。
訪問 Apache GitHub 鏡像 Mirror of This is the Apache log4net logging project git repository
https://github.com/apache/logging-log4net/blob/master/netstandard/log4net/log4net.xproj
與官網說明不一致，官網說支持 ColoredConsoleAppender，不支持 ManagedColoredConsoleAppender，但是代碼顯示對於.Net Core來說，ManagedColoredConsoleAppender可用。