重新熟悉log4j配置

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5" xmlns="http://java.sun.com/xml/ns/javaee"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://java.sun.com/xml/ns/javaee 
         http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">
        
</web-app>

<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee
         http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd"
         version="3.1">
</web-app>

package org.apache.logging.log4j.web;

import java.util.EnumSet;
import java.util.Set;
import javax.servlet.DispatcherType;
import javax.servlet.FilterRegistration;
import javax.servlet.ServletContainerInitializer;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;

import org.apache.logging.log4j.Logger;
import org.apache.logging.log4j.status.StatusLogger;

/**
 * In a Servlet 3.0 or newer environment, this initializer is responsible for starting up Log4j logging before anything
 * else happens in application initialization. For consistency across all containers, if the effective Servlet major
 * version of the application is less than 3.0, this initializer does nothing.
 */
public class Log4jServletContainerInitializer implements ServletContainerInitializer {

    private static final Logger LOGGER = StatusLogger.getLogger();

    @Override
    public void onStartup(final Set<Class<?>> classes, final ServletContext servletContext) throws ServletException {
        if (servletContext.getMajorVersion() > 2 && servletContext.getEffectiveMajorVersion() > 2 &&
                !"true".equalsIgnoreCase(servletContext.getInitParameter(
                        Log4jWebSupport.IS_LOG4J_AUTO_INITIALIZATION_DISABLED
                ))) {
            LOGGER.debug("Log4jServletContainerInitializer starting up Log4j in Servlet 3.0+ environment.");

            final FilterRegistration.Dynamic filter =
                    servletContext.addFilter("log4jServletFilter", Log4jServletFilter.class);
            if (filter == null) {
                LOGGER.warn("WARNING: In a Servlet 3.0+ application, you should not define a " +
                    "log4jServletFilter in web.xml. Log4j 2 normally does this for you automatically. Log4j 2 " +
                    "web auto-initialization has been canceled.");
                return;
            }

            final Log4jWebLifeCycle initializer = WebLoggerContextUtils.getWebLifeCycle(servletContext);
            initializer.start();
            initializer.setLoggerContext(); // the application is just now starting to start up

            servletContext.addListener(new Log4jServletContextListener());

            filter.setAsyncSupported(true); // supporting async when the user isn't using async has no downsides
            filter.addMappingForUrlPatterns(EnumSet.allOf(DispatcherType.class), false, "/*");
        }
    }
}

    /**
     * Returns the major version of the Servlet API that this
     * servlet container supports. All implementations that comply
     * with Version 3.0 must have this method return the integer 3.
     *
     * @return 3
     */
    public int getMajorVersion();
    
    
    /**
     * Returns the minor version of the Servlet API that this
     * servlet container supports. All implementations that comply
     * with Version 3.0 must have this method return the integer 0.
     *
     * @return 0
     */
    public int getMinorVersion();


    /**
     * Gets the major version of the Servlet specification that the
     * application represented by this ServletContext is based on.
     *
     * <p>The value returned may be different from {@link #getMajorVersion},
     * which returns the major version of the Servlet specification
     * supported by the Servlet container.
     *
     * @return the major version of the Servlet specification that the
     * application represented by this ServletContext is based on
     *
     * @throws UnsupportedOperationException if this ServletContext was
     * passed to the {@link ServletContextListener#contextInitialized} method
     * of a {@link ServletContextListener} that was neither declared in
     * <code>web.xml</code> or <code>web-fragment.xml</code>, nor annotated
     * with {@link javax.servlet.annotation.WebListener}
     *
     * @since Servlet 3.0
     */
    public int getEffectiveMajorVersion();
    
    
    /**
     * Gets the minor version of the Servlet specification that the
     * application represented by this ServletContext is based on.
     *
     * <p>The value returned may be different from {@link #getMinorVersion},
     * which returns the minor version of the Servlet specification
     * supported by the Servlet container.
     *
     * @return the minor version of the Servlet specification that the
     * application xrepresented by this ServletContext is based on
     *
     * @throws UnsupportedOperationException if this ServletContext was
     * passed to the {@link ServletContextListener#contextInitialized} method
     * of a {@link ServletContextListener} that was neither declared in
     * <code>web.xml</code> or <code>web-fragment.xml</code>, nor annotated
     * with {@link javax.servlet.annotation.WebListener}
     *
     * @since Servlet 3.0
     */
    public int getEffectiveMinorVersion();