Java Web应用程序中的Log4j错误

Question

I am trying to add Log4j in my Java EE project. I have added the log4j.jar file to my WEB-INF/lib folder and try to implement log4j in one of the Servlets in my project.

Initially I tried it out by using log4j with a basic configuration (without using the log4j.properties file).

My Servlet

import org.apache.log4j.*;

public class classname extends HttpServlet {
    private static final long serialVersionUID = 1L;

    private static Logger log = Logger.getLogger(classname.class);

protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

BasicConfigurator.configure();

log.debug("************************Test Message from Log4j*****************************");

I tried this without the log4j.properties file but I am getting an error like:

log4j:WARN No appenders could be found for logger (org.apache.axis.i18n.ProjectResourceBundle).
log4j:WARN Please initialize the log4j system properly.
log4j:WARN See http://logging.apache.org/log4j/1.2/faq.html#noconfig for more info.

I tested the same in another Java application (not web), it works fine with a basic configuration.

Is there any thing I need to add in my web project?

Answer 1

All these are warnings.To avoid these warnings

Configure the log4j in web.xml first place.I think you configured in some part of wex.xml.

If you configure that log4j at top then you can avoid these warnings.

Answer 2

While loading Axis, log4j is using the default search method for finding a log4j.properties and it's not finding one. This will always cause that warning. I expect the same will happen for each sperate log4j implementation on your classpath. It depends on which class loader is handling the loading of Axis to determine where it will look for and find a properties file.

Answer 3

You don't have to declare nothing in your web.xml.

Because your project is a web application the config file should be on WEB-INF/classes after deployment. I advise you to create a java resource folder to do that. Another approach is to put the config file in your src/main/java.

Beware with the configuration name file. If you are using xml the file name is log4j.xml otherwise log4j.properties.

Answer 4

Write a custom class that implements ServletContextListener like the one shown below. The class looks for a context param named log4jFileName that is defined in web.xml. This locates the log4j XML configuration file. This will configure log4j before other classes use it.

Custom listener:

public class StartupListener implements ServletContextListener
{
    @Override
    public void contextDestroyed(ServletContextEvent arg0)
    {
        // Cleanup code goes here
    }

    @Override
    public void contextInitialized(ServletContextEvent sce)
    {
        Logger logger = null;
        ServletContext servletContext = sce.getServletContext();
        String log4jFile = servletContext.getInitParameter("log4jFileName");
        DOMConfigurator.configure(log4jFile);
        logger = LogManager.getLogger(StartupListener.class.getName());
        logger.debug("Loaded: " + log4jFile);
    }
}

1. In your web.xml define the listener and a context param like so

     <context-param> <param-name>log4jFileName</param-name> <param-value>app/log4j/config/log4jConfig.xml</param-value> </context-param> <listener> <listener-class> com.yourpackage.YourListener </listener-class> </listener> 

2. Now configure your log4jConfig.xml appropriately to ensure that your application logs are logged under an appropriate path. Use a file appender like RollingFileAppender to handle the retention policy for your applications.

Here is a sample log4j XML to help you

Sample log4j XML: (Customize as necessary)

<?xml version="1.0" encoding="UTF-8"?>
<log4j:configuration xmlns:log4j = "http://jakarta.apache.org/log4j/" debug = "false">
    <appender name = "FILE" class = "org.apache.log4j.RollingFileAppender">
        <param name = "File" value = "/usr/local/path/to/application.log"/>
        <param name = "MaxFileSize" value = "5MB"/>
        <param name = "MaxBackupIndex" value = "50"/>
        <layout class = "org.apache.log4j.PatternLayout">
            <param name = "ConversionPattern" value = "[%d{dd/MM/yy hh:mm:ss:sss z}] %5p %c{2}: %m%n"/>
        </layout>
    </appender>
    <category name = "com.your.application.package">
        <priority value = "debug"/>
    </category>
    <category name = "org.apache.catalina">
        <priority value = "error"/>
    </category>
    <category name = "org.hibernate">
        <priority value = "error"/>
    </category>
    <root>
        <priority value = "info"/>
        <appender-ref ref = "FILE"/>
    </root>
</log4j:configuration>