CODEWITHSUNDEEP
javaspring-boottomcat8
Paul Grenyer
Paul Grenyer

Reputation: 1843

Springboot -> Springboot 2: 2 Spring WebApplicationInitializers detected on classpath

I've got a web app I recently upgraded from springboot to springboot 2. When I deploy it to Tomcat 8 it seems to start but doesn't start fully.

In localhost.2019-09-04.log (Tomcat) I have the following error:

2 Spring WebApplicationInitializers detected on classpath

I've tried various things from this post:

2 Spring WebApplicationInitializers detected on classpath

but has no luck. How can I find out which package another WebApplicationInitializers might be in?

Upvotes: 3

Views: 7030

Answers (2)

Wladson Marques
Wladson Marques

Reputation: 21

I had this problem and after doing a new basic spring boot with the bare minimum I still had this problem. The last thing left was to check the innocent application.properties and found with trial and error that there was an invalid property. Once this line was removed, everything worked.

This was the property:

logging.level.org.apache.catalina=DEBUG

Upvotes: 0

Ken Chan
Ken Chan

Reputation: 90427

That log is output from SpringServletContainerInitializer which is Servlet 3.0 ServletContainerInitializer that handles WebApplicationInitializer.

So the most simple way to find out what are these WebApplicationInitializer is to create our own ServletContainerInitializer that also handle WebApplicationInitializer and print their information to console.

@HandlesTypes(WebApplicationInitializer.class)
public class FooServletContainerInitializer implements ServletContainerInitializer {

    @Override
    public void onStartup(Set<Class<?>> c, ServletContext ctx) throws ServletException {
        for (Class<?> clazz : c) {
            System.out.println(clazz);
            System.out.println(clazz.getResource('/' + clazz.getName().replace('.', '/') + ".class"));
            System.out.println("----------------");
        }

    }
}

I am referring to this for how to print the JAR file path of a class.

To register it , create a file META-INF/services/javax.servlet.ServletContainerInitializer. Inside this file , include the fully qualified class name of our ServletContainerInitializer : 

org.foo.bar.FooServletContainerInitializer

Then it should execute during Tomcat starts.

Upvotes: 3

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