Demo版本信息如下：
VS：2019
框架：.Net Core 3.1
Log4Net：2.0.12
思维导图：
【1】添加依赖项
通过nuget添加Log4Net
【2】创建公共类
添加公共类Log4NetLogger，实现ILogger， ILoggerProvider，扩展方法Log4netExtensions
/// <summary>
/// ILogger
/// </summary>
public class Log4NetLogger : ILogger
{
private readonly ILog _log;
private ILoggerRepository _loggerRepository;
public Log4NetLogger(string name, XmlElement xmlElement)
{
_loggerRepository = log4net.LogManager.CreateRepository(
Assembly.GetEntryAssembly(), typeof(log4net.Repository.Hierarchy.Hierarchy));
_log = LogManager.GetLogger(_loggerRepository.Name, name);
log4net.Config.XmlConfigurator.Configure(_loggerRepository, xmlElement);
}
public IDisposable BeginScope<TState>(TState state)
{
return null;
}
public bool IsEnabled(LogLevel logLevel)
{
switch (logLevel)
{
case LogLevel.Critical:
return _log.IsFatalEnabled;
case LogLevel.Debug:
case LogLevel.Trace:
return _log.IsDebugEnabled;
case LogLevel.Error:
return _log.IsErrorEnabled;
case LogLevel.Information:
return _log.IsInfoEnabled;
case LogLevel.Warning:
return _log.IsWarnEnabled;
default:
throw new ArgumentOutOfRangeException(nameof(logLevel));
}
}
public void Log<TState>(LogLevel logLevel, EventId eventId, TState state,
Exception exception, Func<TState, Exception, string> formatter)
{
if (!IsEnabled(logLevel))
{
return;
}
if (formatter == null)
{
throw new ArgumentNullException(nameof(formatter));
}
string message = null;
if (null != formatter)
{
message = formatter(state, exception);
}
if (!string.IsNullOrEmpty(message) || exception != null)
{
switch (logLevel)
{
case LogLevel.Critical:
_log.Fatal(message);
break;
case LogLevel.Debug:
case LogLevel.Trace:
_log.Debug(message);
break;
case LogLevel.Error:
_log.Error(message);
break;
case LogLevel.Information:
_log.Info(message);
break;
case LogLevel.Warning:
_log.Warn(message);
break;
default:
_log.Warn($"Encountered unknown log level {logLevel}, writing out as Info.");
_log.Info(message, exception);
break;
}
}
}
}
/// <summary>
/// ILoggerProvider
/// </summary>
public class Log4NetProvider : ILoggerProvider
{
private readonly string _log4NetConfigFile;
private readonly ConcurrentDictionary<string, Log4NetLogger> _loggers =
new ConcurrentDictionary<string, Log4NetLogger>();
public Log4NetProvider(string log4NetConfigFile)
{
_log4NetConfigFile = log4NetConfigFile;
}
public ILogger CreateLogger(string categoryName)
{
return _loggers.GetOrAdd(categoryName, CreateLoggerImplementation);
}
public void Dispose()
{
_loggers.Clear();
}
private Log4NetLogger CreateLoggerImplementation(string name)
{
return new Log4NetLogger(name, Parselog4NetConfigFile(_log4NetConfigFile));
}
private static XmlElement Parselog4NetConfigFile(string filename)
{
XmlDocument log4netConfig = new XmlDocument();
log4netConfig.Load(File.OpenRead(filename));
return log4netConfig["log4net"];
}
}
/// <summary>
/// 扩展方法 Log4netExtensions
/// </summary>
public static class Log4netExtensions
{
public static ILoggerFactory AddLog4Net(this ILoggerFactory factory, string log4NetConfigFile)
{
factory.AddProvider(new Log4NetProvider(log4NetConfigFile));
return factory;
}
public static ILoggerFactory AddLog4Net(this ILoggerFactory factory)
{
factory.AddProvider(new Log4NetProvider("log4net.config"));
return factory;
}
}
【3】Startup
在Startup中注册log4net
【5】配置文件
添加log4Net.config配置文件，需要注意，log4Net.config文件一定要放在项目的根目录，其次，“属性”—“复制到输出目录”要设置为“始终复制”
<?xml version="1.0" encoding="utf-8" ?>
<!--LOG4日志级别
0：TRACE；记录一些对程序员调试问题有帮助的信息, 其中可能包含一些敏感信息, 所以应该避免在生产环境中启用Trace日志。
1：DEBUG；记录一些在开发和调试阶段有用的短时变量(Short-term usefulness), 所以除非为了临时排除生产环境的故障，开发人员应该尽量避免在生产环境中启用Debug日志。
2：INFO；信息日志，记录应用程序的一些流程, 例如，记录当前api请求的url，请求参数等。
3：WARN；警告日志；记录应用程序中发生的不正常或者未预期的事件信息。这些信息中可能包含错误消息或者错误产生的条件, 例如, 文件未找到，用户不存在。
4：ERROR；错误日志；记录应用程序中某个操作产生的错误和异常信息，如对空值进行操作等。
5：FATAL；毁灭性错误；记录一些需要立刻修复的问题。例如数据丢失，磁盘空间不足。
trace<debug<info<warn<error<fatal -->
<log4net>
<appender name="ErrorRollingFileAppender" type="log4net.Appender.RollingFileAppender">
<file value="D://log//Error//" /><!--对于主要日志错误级别配置对应的文件夹-->
<appendToFile value="true" /><!--是否进行文本追加-->
<rollingStyle value="Date"/>
<datePattern value="yyyy-MM-dd'.log'"/><!--配置日志文件的生成命名规范-->
<maxSizeRollBackups value="100" />
<staticLogFileName value="false" />
<encoding value="utf-8" />
<layout type="log4net.Layout.PatternLayout">
<conversionPattern value="%newline%date [%thread %-5level] %n -- %m%n" />
</layout>
<filter type="log4net.Filter.LevelRangeFilter">
<levelMin value="ERROR" /><!--配置该节点会监听的日志错误级别-->
<levelMax value="FATAL" />
</filter>
</appender>
<appender name="WarnRollingFileAppender" type="log4net.Appender.RollingFileAppender">
<file value="D://log//Warn//" />
<appendToFile value="true" />
<rollingStyle value="Date"/>
<datePattern value="yyyy-MM-dd'.log'"/>
<maxSizeRollBackups value="100" />
<staticLogFileName value="false" />
<encoding value="utf-8" />
<layout type="log4net.Layout.PatternLayout">
<conversionPattern value="%newline%date [%thread %-5level] %n -- %m%n" />
</layout>
<filter type="log4net.Filter.LevelRangeFilter">
<levelMin value="WARN" />
<levelMax value="WARN" />
</filter>
</appender>
<appender name="InfoRollingFileAppender" type="log4net.Appender.RollingFileAppender">
<file value="D://log//Info//" />
<appendToFile value="true" />
<rollingStyle value="Date"/>
<datePattern value="yyyy-MM-dd'.log'"/>
<maxSizeRollBackups value="100" />
<staticLogFileName value="false" />
<encoding value="utf-8" />
<layout type="log4net.Layout.PatternLayout">
<conversionPattern value="%newline%date [%thread %-5level] %n -- %m%n" />
</layout>
<filter type="log4net.Filter.LevelRangeFilter">
<levelMin value="TRACE " />
<levelMax value="INFO" />
</filter>
</appender>
<root>
<level value="All" />
<appender-ref ref="ErrorRollingFileAppender" />
<appender-ref ref="WarnRollingFileAppender" />
<appender-ref ref="InfoRollingFileAppender" />
</root>
</log4net>
【6】测试
此Demo通过MVC实现测试，所以需要添加控制器与视图。
1、同时在Startup中注册MVC相关服务，services.AddControllersWithViews();
2、更改Configure中的UseEndpoints请求为MVC路由配置
app.UseEndpoints(endpoints =>
{
endpoints.MapControllerRoute(
name: "default",
pattern: "{controller=Home}/{action=Index}/{id?}"
);
});
3、控制器中获取对象
private readonly ILogger _logger;
/// <summary>
/// **************通过构造方法获取注册的Log4Net服务
/// </summary>
/// <param name="loggerFactory"></param>
public HomeController(ILoggerFactory loggerFactory)
{
_logger = loggerFactory.CreateLogger<HomeController>();
}
4、调用
public IActionResult Index()
{
//************** 日志对象的引用
_logger.LogInformation($"这是一个一般的日志消息");
_logger.LogWarning($"这是一个警告的日志消息");
_logger.LogError($"这是一个错误的日志消息");
return View();
}
