log4net在Asp.net MVC4中的使用过程_Asp.net

1、安装log4net插件

新建asp.net mvc4项目，并在nuget控制台输入命令，或者直接搜索log4net在线安装，安装log4net

>install-package log4net -version 2.0.15

2、配置web.config文件

<?xml version="1.0" encoding="utf-8"?>
<!--
  有关如何配置 asp.net 应用程序的详细信息，请访问
  https://go.microsoft.com/fwlink/?linkid=301880
  -->
<configuration>
  <configsections>
    <section name="log4net" type="log4net.config.log4netconfigurationsectionhandler,log4net"/>
  </configsections>
  <log4net>
    <root>
      <level value="all"></level>
      <appender-ref ref="sysappender"></appender-ref>
    </root>
    <logger name="weblogger">
      <!--日志输出级别限制，只有大于或等于debug级别才记录日志-->
      <level value="debug"></level>
    </logger>
    <!--以滚动日志方式记录日志-->
    <appender name="sysappender" type="log4net.appender.rollingfileappender,log4net">
      <!--文件存放路径，在项目根目录app_data下-->
      <param name="file" value="app_data/"></param>
      <!--日志是否追加到文件-->
      <param name="appendtofile" value="true"></param>
      <!--滚动日志文件按照日期风格生成-->
      <param name="rollingstyle" value="date"></param>
      <!--日志文件的命名规则-->
      <param name="datepattern" value="&quot;logs_&quot;yyyymmdd&quot;.txt&quot;"></param>
      <!--日志名称是否静态-->
      <param name="staticlogfilename" value="false"></param>
      <!--日志内容的格式和布局-->
      <layout type="log4net.layout.patternlayout,log4net">
        <param name="conversionpattern" value="%d [%t] %-5p %c - %m%n"></param>
        <param name="header" value="-------------------------header---------------------------"></param>
        <param name="footer" value="-------------------------footer---------------------------"></param>
      </layout>
    </appender>
    <!--按照控制台输出日志-->
    <appender name="consoleapp" type="log4net.appender.consoleappender,log4net">
      <layout type="log4net.layout.patternlayout,log4net">
        <param name="conversionpattern" value="%d [%t] %-5p %c - %m%n"></param>
      </layout>
    </appender>
  </log4net>
  <appsettings>
    <add key="webpages:version" value="3.0.0.0" />
    <add key="webpages:enabled" value="false" />
    <add key="clientvalidationenabled" value="true" />
    <add key="unobtrusivejavascriptenabled" value="true" />
  </appsettings>
  <system.web>
    <compilation debug="true" targetframework="4.6.1" />
    <httpruntime targetframework="4.6.1" />
    <httpmodules>
      <add name="applicationinsightswebtracking" type="microsoft.applicationinsights.web.applicationinsightshttpmodule, microsoft.ai.web" />
    </httpmodules>
  </system.web>
  <runtime>
    <assemblybinding xmlns="urn:schemas-microsoft-com:asm.v1">
      <dependentassembly>
        <assemblyidentity name="antlr3.runtime" publickeytoken="eb42632606e9261f" />
        <bindingredirect oldversion="0.0.0.0-3.5.0.2" newversion="3.5.0.2" />
      </dependentassembly>
      <dependentassembly>
        <assemblyidentity name="system.diagnostics.diagnosticsource" publickeytoken="cc7b13ffcd2ddd51" />
        <bindingredirect oldversion="0.0.0.0-4.0.2.1" newversion="4.0.2.1" />
      </dependentassembly>      
      <dependentassembly>
        <assemblyidentity name="newtonsoft.json" publickeytoken="30ad4fe6b2a6aeed" />
        <bindingredirect oldversion="0.0.0.0-11.0.0.0" newversion="11.0.0.0" />
      </dependentassembly>
      <dependentassembly>
        <assemblyidentity name="system.web.optimization" publickeytoken="31bf3856ad364e35" />
        <bindingredirect oldversion="1.0.0.0-1.1.0.0" newversion="1.1.0.0" />
      </dependentassembly>
      <dependentassembly>
        <assemblyidentity name="webgrease" publickeytoken="31bf3856ad364e35" />
        <bindingredirect oldversion="0.0.0.0-1.6.5135.21930" newversion="1.6.5135.21930" />
      </dependentassembly>
      <dependentassembly>
        <assemblyidentity name="system.web.helpers" publickeytoken="31bf3856ad364e35" />
        <bindingredirect oldversion="1.0.0.0-3.0.0.0" newversion="3.0.0.0" />
      </dependentassembly>
      <dependentassembly>
        <assemblyidentity name="system.web.webpages" publickeytoken="31bf3856ad364e35" />
        <bindingredirect oldversion="1.0.0.0-3.0.0.0" newversion="3.0.0.0" />
      </dependentassembly>
      <dependentassembly>
        <assemblyidentity name="system.web.mvc" publickeytoken="31bf3856ad364e35" />
        <bindingredirect oldversion="1.0.0.0-5.2.4.0" newversion="5.2.4.0" />
      </dependentassembly>
    </assemblybinding>
  </runtime>
  <system.webserver>
    <modules>
      <remove name="telemetrycorrelationhttpmodule" />
      <add name="telemetrycorrelationhttpmodule" type="microsoft.aspnet.telemetrycorrelation.telemetrycorrelationhttpmodule, microsoft.aspnet.telemetrycorrelation" precondition="integratedmode,managedhandler" />
      <remove name="applicationinsightswebtracking" />
      <add name="applicationinsightswebtracking" type="microsoft.applicationinsights.web.applicationinsightshttpmodule, microsoft.ai.web" precondition="managedhandler" />
    </modules>
    <validation validateintegratedmodeconfiguration="false" />
  </system.webserver>
  <system.codedom>
    <compilers>
      <compiler language="c#;cs;csharp" extension=".cs" type="microsoft.codedom.providers.dotnetcompilerplatform.csharpcodeprovider, microsoft.codedom.providers.dotnetcompilerplatform, version=2.0.0.0, culture=neutral, publickeytoken=31bf3856ad364e35" warninglevel="4" compileroptions="/langversion:default /nowarn:1659;1699;1701" />
      <compiler language="vb;vbs;visualbasic;vbscript" extension=".vb" type="microsoft.codedom.providers.dotnetcompilerplatform.vbcodeprovider, microsoft.codedom.providers.dotnetcompilerplatform, version=2.0.0.0, culture=neutral, publickeytoken=31bf3856ad364e35" warninglevel="4" compileroptions="/langversion:default /nowarn:41008 /define:_mytype=\&quot;web\&quot; /optioninfer+" />
    </compilers>
  </system.codedom>
</configuration>

日志级别分类（从高到低）：off、fatal、error、warn、info、debug、all

3、初始化log4net

在global.asax中初始化log4net配置

log4net.config.xmlconfigurator.configure();

4、定义异常拦截器

自定义异常拦截器，出现控制器action方法调用出现异常时，将异常信息统一加入到全局队列中，避免日志写入文件并发冲突。

public class myerrorattribute:handleerrorattribute
    {
        public static queue<exception> exceptionqueue = new queue<exception>();
        public override void onexception(exceptioncontext filtercontext)
        {
            exceptionqueue.enqueue(filtercontext.exception);
            base.onexception(filtercontext);
        }
    }

将全局默认异常处理器替换为自己定义的。

public class filterconfig
    {
        public static void registerglobalfilters(globalfiltercollection filters)
        {
            //filters.add(new handleerrorattribute());//默认异常处理器
            filters.add(new myerrorattribute());//自定义异常处理器
        }
    }

5、后台线程轮询异常队列，将日志写入到文件

启动类global.asax.cs文件中定义后台线程，处理异常队列中日志的输出

//启动后台线程，周期性轮询异常队列，将异常输出到文件
            threadpool.queueuserworkitem(o => {
                while(true)
                {
                    if(myerrorattribute.exceptionqueue.count>0)
                    {
                        exception ex = myerrorattribute.exceptionqueue.dequeue();
                        if(ex!=null)
                        {
                            ilog log = logmanager.getlogger("testerror");
                            log.error(ex.tostring());
                        }
                        else
                        {
                            thread.sleep(50);
                        }
                    }
                    else
                    {
                        thread.sleep(50);
                    }
                }
            });

6、控制器中定义异常测试方法

public actionresult testlog()
        {
            int result = 0;
            int x = 1, y = 0;
            result = x / y;
            return view();
        }