我有一个BufferingForwardingAppender configured，可以在发生RollingFileAppender时将最后10封邮件转发给ERROR。在每批邮件之前，我是否可以在日志中显示自定义消息？
我想表明这是一个新的ERROR事件及其上下文，以便日志可读？
我的log4net配置有点像这样：
<appender name="ErrorBufferingAppender" type="log4net.Appender.BufferingForwardingAppender">
<bufferSize value="10" />
<lossy value="true" />
<evaluator type="log4net.Core.LevelEvaluator">
<threshold value="ERROR" />
</evaluator>
<appender-ref ref="ErrorFileAppender" />
</appender>
<appender name="ErrorFileAppender" type="log4net.Appender.RollingFileAppender">
<param name="File" value="logs\Errors.txt"/>
<!-- other important parameters -->
<layout type="log4net.Layout.PatternLayout">
<conversionPattern value="%date [%-4thread] %-5level %logger{1} - %message%newline"/>
</layout>
</appender>
我希望的输出有点像这样
---------- ERROR ----------
2011-05-09 16:59:12,327 [8 ] INFO AppLogger - DiskStorageMonitor.StartMonitoring()
2011-05-09 16:59:12,331 [8 ] INFO AppLogger - DiskStorageMonitor.Initializing File System Watcher...
2011-05-09 16:59:12,341 [8 ] INFO AppLogger - DiskStorageMonitor - LocalSlideDataStorageDrive: C:
2011-05-09 16:59:12,370 [8 ] INFO AppLogger - Transition: From 'MinimumDiskSpaceQuotaState' to 'IdleState'.
2011-05-09 16:59:26,697 [8 ] INFO AppLogger - Transition: From 'IdleState' to 'SlideHolderMacroState'.
2011-05-09 16:59:26,702 [8 ] INFO AppLogger - Transition: From 'SlideHolderMacroState' to 'WaitingForMacroCmdResponseState'.
2011-05-09 16:59:26,781 [12 ] INFO YStageManager - Moving to: -1.25
2011-05-09 16:59:26,782 [14 ] INFO XStageManager - Moving to: -142
2011-05-09 16:59:30,800 [12 ] ERROR RecoveringErrorHandler - An error occurred. Retrying... (snipped exception message & stacktrace)
---------- ERROR ----------
2011-05-09 16:59:30,808 [12 ] WARN MacroCameraRecoverySteps - An error occurred while calling the macro camera. Resetting and retrying...
2011-05-09 16:59:30,809 [12 ] INFO MacroCameraManager - Resetting the Macro Camera.
2011-05-09 16:59:30,886 [12 ] ERROR GetMacroImageCommandHandler - Macro image processing failed for the slide in position 0. (snipped exception message & stacktrace)
答案 0 :(得分：2)
我有一个可能对你有用的解决方案，但这是一个解决方法。基本上，设置两个appender写入同一个文件。当你写一个错误（它会触发Buffer清除你的日志文件）时，让另一个appender先用换行符写“------- Error --------”文本。文本。
你必须稍微使用它才能使它工作，但这应该是一个可行的解决方案。 Apache允许多个appender写入同一个文件。只需确保将+ MinimalLock放在appender上，这样它们就不会锁定文件。这是一个SO链接，解释了两个appender如何写入同一个文件：
答案 1 :(得分：2)
感谢BiggsTRC获得了很好的答案。这是我工作的log4net配置和示例输出。
此appender通过在日志中写入上下文“header”来响应任何ERROR消息。最低限度地锁定日志以允许此缓冲appender写入文件。 ignoresException标记设置为false实际上告诉log4net 此布局将编写异常（而不是在消息下面自动写入）。但实际上我并不想要它，而是另一个支持者。
<appender name="ErrorSectionAppender" type="log4net.Appender.FileAppender">
<filter type="log4net.Filter.LevelMatchFilter">
<levelToMatch value="ERROR" />
</filter>
<filter type="log4net.Filter.DenyAllFilter" />
<file value="logs\Errors.txt" />
<appendToFile value="true" />
<lockingModel type="log4net.Appender.FileAppender+MinimalLock" />
<layout type="log4net.Layout.PatternLayout">
<ignoresException value="false" />
<conversionPattern value="%newline---------- ERROR @ %date ----------%newline" />
</layout>
</appender>
此appender缓冲所有消息，直到出现ERROR消息，然后将最后10条（bufferSize）消息和错误消息转储到ErrorFileAppender。
<appender name="ErrorBufferingAppender" type="log4net.Appender.BufferingForwardingAppender">
<bufferSize value="10" />
<lossy value="true" />
<evaluator type="log4net.Core.LevelEvaluator">
<threshold value="ERROR" />
</evaluator>
<appender-ref ref="ErrorFileAppender" />
</appender>
这是实际的错误文件appender。转换模式是标准的。请注意这里的最小文件锁定。
<appender name="ErrorFileAppender" type="log4net.Appender.RollingFileAppender">
<file value="logs\Errors.txt"/>
<appendToFile value="true"/>
<staticLogFileName value="true"/>
<rollingStyle value="Size"/>
<maxFileSize value="1048576"/>
<maxSizeRollBackups value="-1"/>
<countDirection value="1"/>
<lockingModel type="log4net.Appender.FileAppender+MinimalLock" />
<layout type="log4net.Layout.PatternLayout">
<conversionPattern value="%date [%-4thread] %-5level %logger{1} - %message%newline"/>
</layout>
</appender>
这些appender的输出看起来像这样
---------- ERROR @ 2011-05-13 13:51:22,632 ----------
2011-05-13 13:51:04,937 [9 ] INFO OmnyxScannerLogger - Transition: From 'No State' to 'CommunicationSyncState'.
2011-05-13 13:51:05,363 [12 ] DEBUG IMacroImageProcessor - hello, 10
2011-05-13 13:51:05,369 [19 ] INFO XStageManager - Connecting
2011-05-13 13:51:05,369 [12 ] INFO ZStageManager - Connecting
2011-05-13 13:51:05,369 [16 ] INFO YStageManager - Connecting
2011-05-13 13:51:05,393 [9 ] INFO OmnyxScannerLogger - Transition: From 'CommunicationSyncState' to 'SystemInitializeState'.
2011-05-13 13:51:08,528 [17 ] INFO YStageManager - Homing
2011-05-13 13:51:08,539 [12 ] INFO ZStageManager - Homing
2011-05-13 13:51:22,632 [14 ] ERROR RecoveringErrorHandler - An error occurred. Retrying...
Omnyx.Scanner.CliContracts.ScannerException: Injected: The stage failed to home.
at Omnyx.Scanner.Simulation.ErrorInjection.ErrorInjectionInterceptor.Intercept(IInvocation invocation) in D:\Simulation\ErrorInjection\ErrorInjectionInterceptor.cs:line 42
at Castle.DynamicProxy.AbstractInvocation.Proceed()
at Castle.Proxies.IXStageManagerProxy.Home()
---------- ERROR @ 2011-05-13 13:51:33,758 ----------
2011-05-13 13:51:29,034 [9 ] INFO OmnyxScannerLogger - DiskStorageMonitor.StartMonitoring()
2011-05-13 13:51:29,037 [9 ] INFO OmnyxScannerLogger - DiskStorageMonitor.Initializing File System Watcher...
2011-05-13 13:51:29,046 [9 ] INFO OmnyxScannerLogger - DiskStorageMonitor - LocalSlideDataStorageDrive: C:
2011-05-13 13:51:29,062 [9 ] INFO OmnyxScannerLogger - -- LocalSlideDataStorageOverhead: 0
2011-05-13 13:51:29,075 [9 ] INFO OmnyxScannerLogger - Transition: From 'MinimumDiskSpaceQuotaState' to 'IdleState'.
2011-05-13 13:51:31,727 [9 ] INFO OmnyxScannerLogger - Transition: From 'IdleState' to 'SlideHolderMacroState'.
2011-05-13 13:51:31,732 [9 ] INFO OmnyxScannerLogger - Transition: From 'SlideHolderMacroState' to 'WaitingForMacroCmdResponseState'.
2011-05-13 13:51:31,792 [12 ] INFO YStageManager - Moving to: -1.25
2011-05-13 13:51:31,793 [20 ] INFO XStageManager - Moving to: -142
2011-05-13 13:51:33,758 [12 ] ERROR RecoveringErrorHandler - An error occurred. Retrying...
Omnyx.Scanner.CliContracts.ScannerException: Injected: The macro camera failed.
at Omnyx.Scanner.Simulation.ErrorInjection.ErrorInjectionInterceptor.Intercept(IInvocation invocation) in D:\Simulation\ErrorInjection\ErrorInjectionInterceptor.cs:line 42
at Castle.DynamicProxy.AbstractInvocation.Proceed()
at Castle.Proxies.IMacroCameraManagerProxy.TakeTopLitAndBackLitPictures()