log4net使用

前言

经验表明，日志记录往往是软件开发周期中的重要组成部分。它具有以下几个优点：它可以提供应用程序运行时的精确环境，可供开发人员尽快找到应用程序中的Bug；一旦在程序中加入了Log 输出代码，程序运行过程中就能生成并输出日志信息而无需人工干预。另外，日志信息可以输出到不同的地方（控制台，文件等）以备以后研究之用。

Log4net就是为这样一个目的设计的，用于.NET开发环境的日志记录包。

第一步、下载log4net动态链接库

log4net官方网站：http://logging.apache.org/log4net/

如下图所示针对不同版本的.net framework有不同版本的log4net.dll与之相对应。

第三步、使用

1、在Visual Studio开发项目中引用对应.net framework相应版本的log4net.dll文件

2、在App.config或web.config配置文件中做相应配置

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
  <configSections>
    <section name="log4net" type="log4net.Config.Log4NetConfigurationSectionHandler, log4net"/>
  </configSections>
  <appSettings>
    <add key="Test" value="True"/>
  </appSettings>
  <log4net>
    <appender name="RollingLogFileAppender" type="log4net.Appender.RollingFileAppender">
      <!--日志路径(当前设置为应用程序目录下log目录下)-->
      <param name= "File" value= "log\"/>
      <!--是否是向文件中追加日志-->
      <param name= "AppendToFile" value= "true"/>
      <!--log保留天数-->
      <param name= "MaxSizeRollBackups" value= "10"/>
      <!--日志文件名是否是固定不变的-->
      <param name= "StaticLogFileName" value= "false"/>
      <!--日志文件名格式为:2008-08-31.log-->
      <param name= "DatePattern" value= "yyyy-MM-dd&quot;.log&quot;"/>
      <!--日志根据日期滚动-->
      <param name= "RollingStyle" value= "Date"/>
      <layout type="log4net.Layout.PatternLayout">
        <param name="ConversionPattern" value="%d [%t] %-5p %c - %m%n %loggername" />
      </layout>
    </appender>

    <!-- 控制台前台显示日志 -->
    <appender name="ColoredConsoleAppender" type="log4net.Appender.ColoredConsoleAppender">
      <mapping>
        <level value="ERROR" />
        <foreColor value="Red, HighIntensity" />
      </mapping>
      <mapping>
        <level value="Info" />
        <foreColor value="Green" />
      </mapping>
      <layout type="log4net.Layout.PatternLayout">
        <conversionPattern value="%n%date{HH:mm:ss,fff} [%-5level] %m" />
      </layout>

      <filter type="log4net.Filter.LevelRangeFilter">
        <param name="LevelMin" value="Info" />
        <param name="LevelMax" value="Fatal" />
      </filter>
    </appender>
    <root>
      <!--(高) OFF > FATAL > ERROR > WARN > INFO > DEBUG > ALL (低) -->
      <level value="all" />
      <appender-ref ref="ColoredConsoleAppender"/>
      <appender-ref ref="RollingLogFileAppender"/>
    </root>
  </log4net>
</configuration>

3、添加LogHelper类，LogHelper类代码如下

***命名空间前加上[assembly: log4net.Config.XmlConfigurator(Watch = true)]至关重要

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;

[assembly: log4net.Config.XmlConfigurator(Watch = true)]//这一句很重要
namespace WebApplication1
{
    public class LogHelper
    {

        /// <summary>
        /// 添加异常日志
        /// </summary>
        /// <param name="t">发生异常主体</param>
        /// <param name="ex">异常对象</param>
        public static void AddErrorLog(Type t, Exception ex)
        {
            log4net.ILog log = log4net.LogManager.GetLogger(t);
            log.Error("MyError", ex);
        }

        /// <summary>
        /// 添加异常日志
        /// </summary>
        /// <param name="t">发生异常主体</param>
        /// <param name="msg">异常信息</param>
        public static void AddErrorLog(Type t, string msg)
        {
            log4net.ILog log = log4net.LogManager.GetLogger(t);
            log.Error(msg);
        }

        /// <summary>
        /// 添加信息日志
        /// </summary>
        /// <param name="t"></param>
        /// <param name="ex"></param>
        public static void AddInfoLog(Type t, Exception ex)
        {
            log4net.ILog log = log4net.LogManager.GetLogger(t);
            log.Info("MyInfo", ex);
        }

        /// <summary>
        /// 添加信息日志
        /// </summary>
        /// <param name="t"></param>
        /// <param name="msg"></param>
        public static void AddInfoLog(Type t, string msg)
        {
            log4net.ILog log = log4net.LogManager.GetLogger(t);
            log.Info(msg);
        }

        /// <summary>
        /// 添加警告日志
        /// </summary>
        /// <param name="t"></param>
        /// <param name="ex"></param>
        public static void AddWarnLog(Type t, Exception ex)
        {
            log4net.ILog log = log4net.LogManager.GetLogger(t);
            log.Warn("MyWarn", ex);
        }

        public static void AddWarnLog(Type t, string msg)
        {
            log4net.ILog log = log4net.LogManager.GetLogger(t);
            log.Warn(msg);
        }

        /// <summary>
        /// 添加致命错误日志
        /// </summary>
        /// <param name="t"></param>
        /// <param name="ex"></param>
        public static void AddFatalLog(Type t, Exception ex)
        {
            log4net.ILog log = log4net.LogManager.GetLogger(t);
            log.Fatal("MyFatal", ex);
        }

        public static void AddFatalLog(Type t, string msg)
        {
            log4net.ILog log = log4net.LogManager.GetLogger(t);
            log.Fatal(msg);
        }
    }
}

 4、掉用LogHelper添加日志

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.IO;
using log4net.Config;

namespace log4netDemo_3._5
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            LogHelper.AddInfoLog(typeof(Form1), "Test
");

            int i = 0;
            int j = 10;
            try
            {
                var k = j / i;
            }
            catch (Exception ex)
            {
                LogHelper.AddErrorLog(typeof(Form1), ex);
            }

        }
    }
}