隨筆檔案(496)

Spring提供了一個很實用的工具，可以讓Web應用靈活配置log4j,這個工具類是：

org.springframework.web.util.Log4jConfigListener

org.springframework.web.util.Log4jConfigServlet

由于：

Note that this class has been deprecated for containers implementing
Servlet API 2.4 or higher, in favor of{@linkLog4jConfigListener}.</i><br>
According to Servlet 2.4, listeners must be initialized before load-on-startup
servlets. Many Servlet 2.3 containers already enforce this behavior
(see ContextLoaderServlet javadocs for details). If you use such a container,
this servlet can be replaced with Log4jConfigListener.

建議使用org.springframework.web.util.Log4jConfigListener，而非org.springframework.web.util.Log4jConfigServlet，下面來說下Log4jConfigListener的用法：

其實很簡單，只要在web.xml文件中配置相關參數(shù)和注冊此監(jiān)聽器即可，下面是相應的配置片段：

<!-- 配置log4j配置文件的路徑，可以是xml或 properties文件（此參數(shù)必須配）-->
<context-param>
?? <param-name>log4jConfigLocation</param-name>
?? <param-value>WEB-INF/log4j.properties</param-value>
</context-param>

<!-- 每隔多少毫秒掃描一下配置文件的變化（此參數(shù)可選配） -->
<context-param>
?? <param-name>log4jRefreshInterval</param-name>
?? <param-value>60000</param-value>
</context-param>

<!-- spring框架默認定義webAppRootKey的值為webapp.root，若不配此參數(shù)默認值就是webapp.root（因此，此參數(shù)可選配） -->
<context-param>
?? <param-name>webAppRootKey</param-name>
?? <param-value>home</param-value>
</context-param>

<listener>
?? <listener-class>org.springframework.web.util.Log4jConfigListener</listener-class>
</listener>

這樣就可以在log4j的配置中如下進行了：

log4j.appender.DailyLog=org.apache.log4j.DailyRollingFileAppender
log4j.appender.DailyLog.File=${home}/WEB-INF/logs/log4j.log
log4j.appender.DailyLog.Append=false
log4j.appender.DailyLog.DatePattern='.'yyyy-MM-dd
log4j.appender.DailyLog.layout=org.apache.log4j.PatternLayout
log4j.appender.DailyLog.layout.ConversionPattern=%p %d [%l]%n??? - %m%n