Problem with Commons Logging / Log4j setup in spri

问题:

I have a problem wih a logging setup in a apring webapp deployed under tomcat 6.

The webapp uses the commons-logging api, on runtime log4j should be used. The log file is created but remains empty - no log entries occur.

the setup is the following:

WEB-INF/web.xml:

 <context-param>
    <param-name>log4jConfigLocation</param-name>
    <param-value>/WEB-INF/log4j.xml</param-value>
  </context-param>
  <listener>
    <listener-class>org.springframework.web.util.Log4jConfigListener</listener-class>
  </listener>

WEB-INF/classes/commons-logging.properties:

org.apache.commons.logging.Log=org.apache.commons.logging.impl.Log4JLogger

WEB-INF/log4j.xml:

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

  <appender name="CONSOLE" class="org.apache.log4j.ConsoleAppender">
    ...
  </appender>
  <appender name="FILE" class="org.apache.log4j.RollingFileAppender">
    <param name="File" value="${catalina.home}/logs/my.log"/>
    ...
  </appender>

  <logger name="my.package">
    <level value="INFO"/>
  </logger>

  <root>
    <level value="ERROR"/>
    <appender-ref ref="CONSOLE"/>
    <appender-ref ref="FILE"/>
  </root>
</log4j:configuration>

The file logs/my.log is created, but no logs appear. The are info logs on the tomcat console, but not with the layout pattern configured.

The commons-logging-1.1.1.jar and log4j-1.2.14.jar are included in WEB-INF/lib. Any idea what is wrong here?

回答1:

There are numerous documented instances on the web warning people about the use of commons-logging. So much so, that SLF4J is gaining a lot of popularity.

Considering that you are not interested in using Tomcat with Log4j, you should just use Log4j directly in your application. Particularly if there is no chance that you'll be switching logging frameworks in the future. It'll reduce the complexity of your application, and get rid of any class loader issues you are having with commons-logging.

This should be a relatively easy search and replace in your text, as commons-logging and log4j both use a similar call structure for their logging methods.

回答2:

Be especially careful that you have not placed log4j.jar in the Tomcat commons/lib directory. If the root classloader loads the log4j libraries, you'll run into conflicts and initialization problems when your webapps also try to use log4j.

If you need to use log4j for common Tomcat logging, you'll need to be careful that your webapps do not attempt to load log4j as well. If you have multiple webapps on the server, then you'll need discipline that each webapp's log initialization does not stomp on the initialization of other webapps. Each webapp will need to use unique Logger IDs, which can be accomplished with unique package names.

Using a common log4j in Tomcat with multiple webapps causes serious conflicts when you have shared libraries that all want to do logging, such as Hibernate or Spring. The next webapp that attempts to initialize log4j may close the logger of the previous one. It can be a mess.

回答3:

I had similar problem and found a fix now. Start tomcat with additional parameter:

-Dorg.apache.commons.logging.LogFactory=org.apache.commons.logging.impl.LogFactoryImpl

回答4:

You need to compile the extra component for full commons-logging. By default Tomcat 6 uses a hardcoded implementation of commons-logging that always delegates to java.util.logging.

Building instructions here http://tomcat.apache.org/tomcat-6.0-doc/building.html

Then replace the tomcat-juli.jar in the /bin directory of Tomcat and place the tomcat-juli-adapters.jar in the /lib directory along with log4j and config.

回答5:

if you are using log4j +common logging, you can avoid most of above configurations. common logging LogFactory have a discovery feature similar to JAXP, in following precedence, searching for Log implementations, 1. configuration attribute org.apache.commons.logging.Log inside file commons-logging.properties 2. system property org.apache.commons.logging.Log 3. If the Log4J available at class path, use the corresponding wrapper class (Log4JLogger). 4. Jdk14Logger 5. SimpleLog

just make sure, both common-logging.jar and common-logging-api.jar and log4j.jar at classpath.

回答6:

May be i am wrong. Please try the following:

A) Add appender to my.package as: OR B) Reduce the log leve of root to INFO