.net Core log4net日誌

.net Core 操作日誌

簡單使用:只能在控制檯中打印

```csharp
	public class ValuesController : ControllerBase
		{
			ILogger<ValuesController> logger;
			//構造函數注入Logger
			public ValuesController(ILogger<ValuesController> logger)
			{
				this.logger = logger;
			}
			[HttpGet]
			public IEnumerable<string> Get()
			{
				logger.LogWarning("Warning");
				logger.LogError("Error");
				logger.LogDebug("Debug");
				return new string[] { "value1", "value2" };
			}
		}
```

添加Log4Net

Nuget安裝Microsoft.Extensions.Logging.Log4Net.AspNetCore

註冊方式一

```csharp
	public static IWebHostBuilder CreateWebHostBuilder(string[] args) =>
        WebHost.CreateDefaultBuilder(args)
            .UseStartup<Startup>()
        .ConfigureLogging((context, logger) =>{
            logger.AddFilter("System", LogLevel.Warning);
            logger.AddFilter("Microsoft", LogLevel.Warning);
            logger.AddLog4Net();
        })
        .ConfigureLogging(option=> {
            option.ClearProviders();
            option.AddConsole();
        });
```

註冊方式二:Startup.cs中添加ILoggerFactory 注入AddLog4Net();

```csharp
	 public void Configure(IApplicationBuilder app, IHostingEnvironment env,ILoggerFactory logger)
    {
        if (env.IsDevelopment())
        {
            app.UseDeveloperExceptionPage();
        }
        else
        {
            // The default HSTS value is 30 days. You may want to change this for production scenarios, see https://aka.ms/aspnetcore-hsts.
            app.UseHsts();
        }
        logger.AddLog4Net();
        app.UseHttpsRedirection();
        app.UseMvc();
    }
```
>使用：和簡單使用一致或者用以下的方法調用（此時調用會報錯`FileNotFoundException: Could not find file 'F:\CoreStu\CoreDemo\CoreDemo_Logging\bin\Debug\netcoreapp2.2\log4net.config'`需要先配置log4net.config)
```csharp
	var logger=new LoggerFactory().AddLog4Net().CreateLogger("logs");
	logger.LogError("這是錯誤信息");
```

添加Log4Net.Config文件

```xml
	<log4net>
	  <root>
		<level value="ALL" ref="infoAppender" />
		<appender-ref ref="infoAppender" />
		<appender-ref ref="errorAppender" />
		<appender-ref ref="debugAppender" />
	  </root>

	  <!-- 日誌的等級，它們由高到底分別爲： OFF > FATAL > ERROR > WARN > INFO > DEBUG > ALL -->
	  <!--信息日誌配置-->
	  <appender name="infoAppender" type="log4net.Appender.RollingFileAppender">
		<param name="File" value="Logs\Info\info.log" />
		<param name="AppendToFile" value="true" />
		<param name="MaxFileSize" value="10240" />
		<param name="MaxSizeRollBackups" value="100" />
		<param name="PreserveLogFileNameExtension" value="true" />
		<param name="StaticLogFileName" value="false" />
		<param name="DatePattern" value="yyyyMMdd" />
		<param name="RollingStyle" value="Date" />
		<layout type="log4net.Layout.PatternLayout">
		  <conversionPattern value="%date [%thread] %-5level %logger - %message%newline" />
		</layout>
		<filter type="log4net.Filter.LevelRangeFilter">
		  <param name="LevelMin" value="INFO" />
		  <param name="LevelMax" value="INFO" />
		</filter>
	  </appender>

	  <!--調試日誌配置-->
	  <appender name="debugAppender" type="log4net.Appender.RollingFileAppender">
		<param name="File" value="Logs\Debug\debug.log" />
		<param name="AppendToFile" value="true" />
		<param name="MaxFileSize" value="10240" />
		<param name="MaxSizeRollBackups" value="100" />
		<param name="PreserveLogFileNameExtension" value="true" />
		<param name="StaticLogFileName" value="false" />
		<param name="DatePattern" value="yyyyMMdd" />
		<param name="RollingStyle" value="Date" />
		<layout type="log4net.Layout.PatternLayout">
		  <conversionPattern value="%date [%thread] %-5level %logger - %message%newline" />
		</layout>
		<filter type="log4net.Filter.LevelRangeFilter">
		  <param name="LevelMin" value="DEBUG" />
		  <param name="LevelMax" value="DEBUG" />
		</filter>
	  </appender>

	  <!--錯誤日誌配置-->
	  <appender name="errorAppender" type="log4net.Appender.RollingFileAppender">
		<param name="File" value="Logs\Error\Err.log" />
		<param name="AppendToFile" value="true" />
		<param name="MaxFileSize" value="10240" />
		<param name="MaxSizeRollBackups" value="100" />
		<param name="PreserveLogFileNameExtension" value="true" />
		<param name="StaticLogFileName" value="false" />
		<param name="DatePattern" value="yyyyMMdd" />
		<param name="RollingStyle" value="Date" />
		<layout type="log4net.Layout.PatternLayout">
		  <conversionPattern value="%date [%thread] %-5level %logger - %message%newline" />
		</layout>
		<filter type="log4net.Filter.LevelRangeFilter">
		  <param name="LevelMin" value="ERROR" />
		  <param name="LevelMax" value="ERROR" />
		</filter>
	  </appender>
	</log4net>
```

參考 Log4Net使用