Eclipse 开始 Tomcat 中没有 servlets 的日志

Question

I am using

• Tomcat 9
• Eclipse Version: 2020-09 (4.17.0)
• Apache Maven 3.6.3

and I am starting to write a servlet, which runs in the Tomcat container. When I run it in Ecplise ( Debug on Server ) I can see some logging output from Tomcat. Like

INFO: Initializing ProtocolHandler ["http-nio-8080"]
Dec 08, 2020 4:21:34 PM org.apache.coyote.AbstractProtocol init
INFO: Initializing ProtocolHandler ["ajp-nio-127.0.0.1-8009"]
Dec 08, 2020 4:21:34 PM org.apache.catalina.startup.Catalina load
INFO: Server initialization in [1291] milliseconds
Dec 08, 2020 4:21:34 PM org.apache.catalina.core.StandardService startInternal
INFO: Starting service [Catalina]
Dec 08, 2020 4:21:34 PM org.apache.catalina.core.StandardEngine startInternal
INFO: Starting Servlet engine: [Apache Tomcat/9.0.39]
Dec 08, 2020 4:21:36 PM org.apache.jasper.servlet.TldScanner scanJars
INFO: At least one JAR was scanned for TLDs yet contained no TLDs. Enable debug logging for this logger for a complete list of JARs that were scanned but no TLDs were found in them. Skipping unneeded JARs during scanning can improve startup time and JSP compilation time.
Dec 08, 2020 4:21:38 PM org.glassfish.jersey.server.wadl.WadlFeature configure
WARNING: JAXBContext implementation could not be found. WADL feature is disabled.
Dec 08, 2020 4:21:39 PM org.apache.catalina.startup.HostConfig deployDirectory
INFO: Deploying web application directory [/home/myname/bin/tomcat/apache-tomcat-9.0.39/webapps/examples]
Dec 08, 2020 4:21:39 PM org.apache.catalina.core.ApplicationContext log
INFO: ContextListener: contextInitialized()
Dec 08, 2020 4:21:39 PM org.apache.catalina.core.ApplicationContext log
INFO: SessionListener: contextInitialized()

... ...

The servlet runs fine and the start looks like this:

public class MyMain extends Application {
    
    private final static Logger logger = LoggerFactory.getLogger(SdpApiMain.class);
    
    @Override
    public Set<Class<?>> getClasses() {
        Set<Class<?>> s = new HashSet<Class<?>>();
        s.add(Test.class);
        s.add(User.class);
        logger.debug("We are in main class, collectiong resources.");
        return s;
    }
}

But I do not see the debug line .

For logging I am using slf4j 1.7 and log4j2 . I have the following log4j2.xml

<?xml version="1.0" encoding="UTF-8"?>
<Configuration status="WARN">
  <Appenders>
    <Console name="Console" target="SYSTEM_OUT">
      <PatternLayout pattern="%d{HH:mm:ss.SSS} [%t] %-5level %logger{36} - %msg%n"/>
    </Console>
  </Appenders>
  <Loggers>
    <Root level="debug">
      <AppenderRef ref="Console"/>
    </Root>
  </Loggers>
</Configuration>

Do I just need a different console view in Eclipse? Anything wrong with my configuration and how can I debug it?

Answer 1

Two steps for a solution for this problem:

We are talking about Eclipse, so I have added the -Dlog4j2.debug=true flag to

Run Configurations -> Arguments (tab)

Then I could see that log4j2 needs the log4j2-web dependency in this setup. And it complained that it could not see a configuration file, so I added the log4j2.xml the right place (in the classpath). (Eclipse: right click on src/main/resources -> new 'other' -> xml file .) This folder was already in my classpath, the formerly used one not.

When there is no configuration file it uses it sdt configuration, which has log level error as default.