programming panda

Default location of log4j properties is in /WEB-INF/classes/logj4.properties. There are ways to point log4j to different properties. In spring, we can do something like this.

<!-- log4j setting -->
    <bean id="log4jInitialization"
 class="org.springframework.beans.factory.config.MethodInvokingFactoryBean">
  <property name="targetClass"
   value="org.springframework.util.Log4jConfigurer" />
  <property name="targetMethod" value="initLogging" />
  <property name="arguments">
   <list>
    <value>log4j.properties</value>
   </list>
  </property>
 </bean>

where initLogging takes (String location), you can use absolute path or relative path here. But a more elegant way is to use a variable for the application root. like this

<value>${webapp.root}/${log4j.properties.location}</value>

You can get the ${webapp.root} from webAppRootKey. To bring it to the next level we can group all configs into 1 properties file and that will make the build process easier.

The full setup looks something like this

/WEB-INF/web.xml

<listener>
        <listener-class>org.springframework.web.util.WebAppRootListener</listener-class>
    </listener>
<listener>
        <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
    </listener>
<context-param>
        <param-name>contextConfigLocation</param-name>
        <param-value>
            /WEB-INF/applicationContext.xml
</param-value>
    </context-param>
    <context-param>
        <param-name>webAppRootKey</param-name>
        <param-value>webapp.root</param-value>
    </context-param>

/WEB-INF/applicationContext.xml

<bean id="propertyConfigurer"
      class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
      <property name="locations">
      <list>
                <value>/WEB-INF/spring-config/dev.properties</value>
   </list>
   </property>
 </bean>
<!-- log4j setting -->
    <bean id="log4jInitialization"
 class="org.springframework.beans.factory.config.MethodInvokingFactoryBean">
  <property name="targetClass"
   value="org.springframework.util.Log4jConfigurer"/>
  <property name="targetMethod" value="initLogging"/>
  <property name="arguments">
   <list>
    <value>${webapp.root}/${log4j.properties.location}</value>
   </list>
  </property>
 </bean>

/WEB-INF/spring-config/dev.properties

#log4j setting
log4j.properties.location=WEB-INF/log4j-config/log4j.dev.properties

/WEB-INF/log4j-config/log4j.dev.properties

log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.Target=System.out
log4j.appender.stdout.Threshold=DEBUG
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern=%d{ABSOLUTE} %5p %c{1}:%L - %m%n

log4j.rootLogger=DEBUG, stdout

/WEB-INF/log4j-config/log4j.prod.properties

# Configuration for receiving e-mails when ERROR messages occur.
log4j.appender.mail=org.apache.log4j.net.SMTPAppender
log4j.appender.mail.To=to@mydomain.com
log4j.appender.mail.From=from@mydomain.com
log4j.appender.mail.SMTPHost=smtp.mydomain.com
log4j.appender.mail.Threshold=ERROR
log4j.appender.mail.BufferSize=1
log4j.appender.mail.Subject=An application error occured
log4j.appender.mail.layout=org.apache.log4j.HTMLLayout

# Standrd System.out appender
log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.Target=System.out
log4j.appender.stdout.Threshold=INFO
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern=%d{ABSOLUTE} %5p %c{1}:%L - %m%n

log4j.rootLogger=INFO, stdout, mail