聶永的博客

一。log4j的基礎知識

　1.log4j有三種主要組件：logger、appender and layout
　　2.Log4j提供的appender有以下幾種：
　　org.apache.log4j.ConsoleAppender（控制臺)
　　org.apache.log4j.FileAppender（文件)
　　org.apache.log4j.DailyRollingFileAppender（每天產生一個日志文件）
　　org.apache.log4j.RollingFileAppender（文件大小到達指定尺寸的時候產生一個新的文件）
　　org.apache.log4j.WriterAppender（將日志信息以流格式發送到任意指定的地方）
　　3.Log4j提供的layout有以下幾種：
　　org.apache.log4j.HTMLLayout（以HTML表格形式布局)
　　org.apache.log4j.PatternLayout（可以靈活地指定布局模式）
　　org.apache.log4j.SimpleLayout（包含日志信息的級別和信息字符串）
　　org.apache.log4j.TTCCLayout（包含日志產生的時間、線程、類別等等信息）
　　4.Log4j提供的幾種輸出格式：
　?。：Used to output the method name where the logging request was issued.
　?。：Used to output the application supplied message associated with the logging event.
　　％l：Used to output location information of the caller which generated the logging event
　?。：Used to output the line number from where the logging request was issued.
　　％p：Used to output the priority of the logging event.
　?。：Outputs the platform dependent line separator character or characters.
　?。：Used to output the number of milliseconds elapsed since the start of the application until the creation of the logging event.
　?。：Used to output the file name where the logging request was issued.
　　％d：Used to output the date of the logging event.
　?。：Used to output the category of the logging event
　?。：Used to output the fully qualified class name of the caller issuing the logging request
　　5.如果是對于效率要求比較高的話，要在log.debug()之前加上log.isDebugEnabled()進行判斷，這樣能夠大大減少執行時間
　　6.對于各個appenders,共有的屬性是layout（一般設置為org.apache.log4j.PatternLayout）,Threshold(Log的級別)
　　(1)ConsoleAppender:Target(System.out和System.err)
　　(2)FileAppender:File(定義輸出的文件名），Append（定義是否為追加）
　　(3）DailyRollingFileAppender（除FileAppender屬性外）:MaxFileSize（最大文件大小），MaxBackupIndex（）

以上來自http://www.wangchao.net.cn/bbsdetail_64587.html

二。詳細配置log4j.xml文件

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE log4j:configuration SYSTEM "log4j.dtd">

<log4j:configuration threshold="debug"
xmlns:log4j='http://jakarta.apache.org/log4j/'>

    <appender name="console.CONSOLE"
  class="org.apache.log4j.ConsoleAppender">
  <param name="threshold" value="debug" />
  <layout class="org.apache.log4j.PatternLayout">
  <!--
   <param name="ConversionPattern" value="%d{HH:mm:ss}[%C.%M(%L)-%p] %m%n"/>
  -->
  <param name="ConversionPattern" value="%d{HH:mm:ss}[%C(%L)-%p] %m%n"/>
  </layout>
</appender>

<appender name="file.text.SYSFILE"
  class="org.apache.log4j.RollingFileAppender">
  <param name="threshold" value="error" />
  <param name="file" value="/juyee.log" />
  <param name="maxFileSize" value="2MB" />
  <param name="maxBackupIndex" value="5" />
  <param name="append" value="true" />
  <layout class="org.apache.log4j.PatternLayout">
   <param name="ConversionPattern"
    value="%-d{yyyy-MM-dd HH:mm:ss.SSS} [%p]-[%c] %m%n" />
  </layout>
</appender>
<appender name="file.text.DATE_FILE"
  class="org.apache.log4j.DailyRollingFileAppender">
  <param name="threshold" value="debug" />
  <param name="file" value="/juyee.log" />
  <param name="append" value="true" />
  <param name="datePattern" value="'.'yyyy-MM-dd" />
  <!-- each hour
   <param name="DatePattern" value="'.'yyyy-MM-dd-HH"/>
  -->
  <layout class="org.apache.log4j.PatternLayout">
   <param name="ConversionPattern" value="%d %-5p [%c] %m%n" />
  </layout>
</appender>
<appender name="file.text.APPFILE"
  class="org.apache.log4j.RollingFileAppender">
  <param name="threshold" value="error" />
  <param name="file" value="${webapp.root}/WEB-INF/logs/juyee.log" />
  <param name="maxFileSize" value="1024KB" />
  <param name="maxBackupIndex" value="5" />
  <param name="append" value="true" />
  <layout class="org.apache.log4j.PatternLayout">
   <param name="ConversionPattern"
    value="%d %-5p %c - %m [%t] (%F:%L)%n" />
  </layout>
</appender>
<appender name="file.html.HTML"
  class="org.apache.log4j.RollingFileAppender">
  <param name="threshold" value="error" />
  <param name="file" value="/juyee-log.html" />
  <param name="maxFileSize" value="1024KB" />
  <param name="maxBackupIndex" value="5" />
  <param name="append" value="true" />
  <layout class="org.apache.log4j.HTMLLayout" />
</appender>
<appender name="file.xml.XML"
  class="org.apache.log4j.RollingFileAppender">
  <param name="threshold" value="error" />
  <param name="file" value="/juyee-log.xml" />
  <param name="maxFileSize" value="1024KB" />
  <param name="maxBackupIndex" value="5" />
  <param name="append" value="true" />
  <layout class="org.apache.log4j.xml.XMLLayout" />
</appender>

  <appender name="mail.MAIL" class="org.apache.log4j.net.SMTPAppender">
  <param name="threshold" value="debug"/>
            <!--
        <param name="threshold" value="fatal"/>
        -->
  <param name="BufferSize" value="10"/>
  <param name="From" value="yangguanjun@justonetech.com"/>
  <param name="SMTPHost" value=">
  <param name="Subject" value="juyee-log4jMessage"/>
  <param name="To" value="yangguanjun@justonetech.com"/>
  <layout class="org.apache.log4j.PatternLayout">
  <param name="ConversionPattern" value="%-d{yyyy-MM-dd HH:mm:ss.SSS} [%p]-[%c] %m%n" />
  </layout>
  </appender>

<appender name="remote.CHAINSAW"
  class="org.apache.log4j.net.SocketAppender">
  <param name="threshold" value="fatal" />
  <param name="remoteHost" value="localhost" />
  <param name="port" value="4445" />
  <param name="locationInfo" value="true" />
</appender>

<category name="com.juyee" additivity="true">
  <priority value="info" />
  <appender-ref ref="console.CONSOLE" />
  <!--
  <appender-ref ref="file.text.DATE_FILE" />
  -->
</category>

<category name="com.co" additivity="true">
  <priority value="debug" />
  <appender-ref ref="console.CONSOLE" />
  <appender-ref ref="file.text.DATE_FILE" />
</category>

<category name="org" additivity="true">
  <priority value="WARN" />
  <appender-ref ref="console.CONSOLE" />
  <!--
  <appender-ref ref="file.text.DATE_FILE" />
  -->
</category>

<root>
  <!--
   <level value="trace" />
   <level value="debug" />
   <level value="info" />
   <level value="warn" />
   <level value="error" />
   <level value="fatal" />
   <appender-ref ref="console.CONSOLE" />
   <appender-ref   ref="file.text.DATE_FILE"/>
  -->
</root>
</log4j:configuration>

Refer ： http://dolphin-ygj.javaeye.com/blog/312504

三。加載log4j.xml

Refer : http://smilecertian.blog.sohu.com/52335422.html