Log4j 配置的webAppRootKey参数问题

为了让Web项目中的Spring 使用Log4j做如下配置：

1、在web.xml中添加如下内容：

<!--如果不定义webAppRootKey参数，那么webAppRootKey就是缺省的"webapp.root"。但最好设置，以免项目之间的名称冲突。

如我这里有两个项目都在web.xml都没配置webAppRootKey，那么这两个项目发布到tomcat时就会出现如下的异常：

 

严重: Exception sending context initialized event to listener instance of class org.springframework.web.util.Log4jConfigListener
java.lang.IllegalStateException: Web app root system property already set to different value: 'webapp.root' = [D:\apache-tomcat-6.0.29\webapps\UpLoadAndDownLoad\] instead of [D:\apache-tomcat-6.0.29\webapps\w\] - Choose unique values for the 'webAppRootKey' context-param in your web.xml files!
    at org.springframework.web.util.WebUtils.setWebAppRootSystemProperty(WebUtils.java:146)
    at org.springframework.web.util.Log4jWebConfigurer.initLogging(Log4jWebConfigurer.java:118)
    at org.springframework.web.util.Log4jConfigListener.contextInitialized(Log4jConfigListener.java:47)
    at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:4135)
    at org.apache.catalina.core.StandardContext.start(StandardContext.java:4630)
    at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:791)
    at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:771)
    at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:546)
    at org.apache.catalina.startup.HostConfig.deployDirectory(HostConfig.java:1041)
    at org.apache.catalina.startup.HostConfig.deployDirectories(HostConfig.java:964)
    at org.apache.catalina.startup.HostConfig.deployApps(HostConfig.java:502)
    at org.apache.catalina.startup.HostConfig.start(HostConfig.java:1277)
    at org.apache.catalina.startup.HostConfig.lifecycleEvent(HostConfig.java:321)
    at org.apache.catalina.util.LifecycleSupport.fireLifecycleEvent(LifecycleSupport.java:119)
    at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1053)
    at org.apache.catalina.core.StandardHost.start(StandardHost.java:785)
    at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1045)
    at org.apache.catalina.core.StandardEngine.start(StandardEngine.java:445)
    at org.apache.catalina.core.StandardService.start(StandardService.java:519)
    at org.apache.catalina.core.StandardServer.start(StandardServer.java:710)
    at org.apache.catalina.startup.Catalina.start(Catalina.java:581)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
    at java.lang.reflect.Method.invoke(Unknown Source)
    at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:289)
    at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:414)
2010-10-10 17:18:18 org.apache.catalina.core.StandardContext start
严重: Error listenerStart

严重: Exception sending context initialized event to listener instance of class org.springframework.web.util.Log4jConfigListener

java.lang.IllegalStateException: Web app root system property already set to different value: 'webapp.root' = [D:\apache-tomcat-6.0.29\webapps\UpLoadAndDownLoad\] instead of [D:\apache-tomcat-6.0.29\webapps\w\] - Choose unique values for the 'webAppRootKey' context-param in your web.xml files!

	at org.springframework.web.util.WebUtils.setWebAppRootSystemProperty(WebUtils.java:146)

	at org.springframework.web.util.Log4jWebConfigurer.initLogging(Log4jWebConfigurer.java:118)

	at org.springframework.web.util.Log4jConfigListener.contextInitialized(Log4jConfigListener.java:47)

	at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:4135)

	at org.apache.catalina.core.StandardContext.start(StandardContext.java:4630)

	at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:791)

	at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:771)

	at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:546)

	at org.apache.catalina.startup.HostConfig.deployDirectory(HostConfig.java:1041)

	at org.apache.catalina.startup.HostConfig.deployDirectories(HostConfig.java:964)

	at org.apache.catalina.startup.HostConfig.deployApps(HostConfig.java:502)

	at org.apache.catalina.startup.HostConfig.start(HostConfig.java:1277)

	at org.apache.catalina.startup.HostConfig.lifecycleEvent(HostConfig.java:321)

	at org.apache.catalina.util.LifecycleSupport.fireLifecycleEvent(LifecycleSupport.java:119)

	at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1053)

	at org.apache.catalina.core.StandardHost.start(StandardHost.java:785)

	at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1045)

	at org.apache.catalina.core.StandardEngine.start(StandardEngine.java:445)

	at org.apache.catalina.core.StandardService.start(StandardService.java:519)

	at org.apache.catalina.core.StandardServer.start(StandardServer.java:710)

	at org.apache.catalina.startup.Catalina.start(Catalina.java:581)

	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)

	at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)

	at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)

	at java.lang.reflect.Method.invoke(Unknown Source)

	at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:289)

	at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:414)

2010-10-10 17:18:18 org.apache.catalina.core.StandardContext start

严重: Error listenerStart

 

所以对多个项目要对webAppRootKey进行配置，这里主要是让log能将日志写到对应项目根目录下，如我配置这两个项目的webAppRootKey为

 

<!-- 应用路径  -->
    <context-param>
        <param-name>webAppRootKey</param-name>
        <param-value>spring.webapp.root</param-value>
    </context-param>

<!-- 应用路径  -->

	<context-param>

		<param-name>webAppRootKey</param-name>

		<param-value>spring.webapp.root</param-value>

	</context-param>

 

 

<!-- 应用路径  -->
    <context-param>
        <param-name>webAppRootKey</param-name>
        <param-value>spring.webapp.root2</param-value>
    </context-param>

<!-- 应用路径  -->

	<context-param>

		<param-name>webAppRootKey</param-name>

		<param-value>spring.webapp.root2</param-value>

	</context-param>

 

这样就不会出现冲突了。

定义以后，在Web Container启动时将把ROOT的绝对路径写到系统变量里。
然后log4j的配置文件里就可以用${webName.root }来表示Web目录的绝对路径，把log文件存放于webapp中。

 

<!--此参数用于后面的“Log4jConfigListener”-->
<context-param>
<param-name>webAppRootKey</param-name>
<param-value>webName.root</param-value>
</context-param>

<!--由Sprng载入的Log4j配置文件位置-->
<context-param>
<param-name>log4jConfigLocation</param-name>
<param-value>/WEB-INF/log4j.properties</param-value>
</context-param>

<!--Spring默认刷新Log4j配置文件的间隔,单位为millisecond-->
<context-param>
<param-name>log4jRefreshInterval</param-name>
<param-value>60000</param-value>
</context-param>

<!-- Web 项目 Spring 加载 Log4j 的监听 -->
<listener>
<listener-class>org.springframework.web.util.Log4jConfigListener</listener-class>
</listener>

<!--此参数用于后面的“Log4jConfigListener”-->

<context-param>

<param-name>webAppRootKey</param-name>

<param-value>webName.root</param-value>

</context-param>



<!--由Sprng载入的Log4j配置文件位置-->

<context-param>

<param-name>log4jConfigLocation</param-name>

<param-value>/WEB-INF/log4j.properties</param-value>

</context-param>



<!--Spring默认刷新Log4j配置文件的间隔,单位为millisecond-->

<context-param>

<param-name>log4jRefreshInterval</param-name>

<param-value>60000</param-value>

</context-param>



<!-- Web 项目 Spring 加载 Log4j 的监听 -->

<listener>

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

</listener>

 

2、编写log4j.properties属性文件,使用web.xml配置的全局变量：

log4j.appender.A_default.File=${webName.root}/WEB-INF/logs/log4j.log

详细内容略。

问题：
如上配置后，log4j.properties属性文件的存放位置，应在Web项目中的WEB-INF下，而不是默认的/WEB-INF/classes下。
可在做spring 的单元测试时，默认读取classes下的log4j.properties,不知该问题如何解决？

如果把log4j.properties存放在/WEB-INF/classes/log4j.properties下的话，会在启动Tomcat时报错：

log4j:ERROR setFile(null,true) call failed.
java.io.FileNotFoundException: \WEB-INF\logs\log4j.log (系统找不到指定的路径。)

可在\WEB-INF\logs\log4j.log 却可以看到log4j.log文件已存在Spring的日志输出信息。
分析可能是其他的类在加载log4j.properties时，无法读取${webName.root}变量的值。

转自：http://nopainnogain.iteye.com/blog/780542