Spring boot on appengine standard

Question

I'm trying to run my code on local appengine simulator but I'm still getting error with info that class ServletInitializer is not a javax.servlet.Servlet There is log from startup

Connected to server
2017-09-27 15:32:49.323:INFO:oejs.Server:main: jetty-9.3.18.v20170406
2017-09-27 15:32:53.756:INFO:oeja.AnnotationConfiguration:main: Scanning elapsed time=3587ms
wrz 27, 2017 1:32:53 PM com.google.appengine.tools.development.ApiProxyLocalImpl log
INFO: javax.servlet.ServletContext log: 2 Spring WebApplicationInitializers detected on classpath

  .   ____          _            __ _ _
 /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
 \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
  '  |____| .__|_| |_|_| |_\__, | / / / /
 =========|_|==============|___/=/_/_/_/
 :: Spring Boot ::        (v1.5.7.RELEASE)
 ...
 ... 
 ...
 ...
 2017-09-27 13:33:03.777 [main]       [32mINFO[m -o.s.b.StartupInfoLogger- Started ServletInitializer in 9.329 seconds (JVM running for 15.913)
2017-09-27 13:33:04.045 [main]       [34mDEBUG[m -o.s.w.f.GenericFilterBean- Initializing filter 'provideJwtAuthTokenFilter'
2017-09-27 13:33:04.045 [main]       [34mDEBUG[m -o.s.w.f.GenericFilterBean- Filter 'provideJwtAuthTokenFilter' configured successfully
2017-09-27 13:33:04.047 [main]       [31mERROR[m -c.g.a.t.d.ApiProxyLocalImpl- javax.servlet.ServletContext log: unavailable
javax.servlet.UnavailableException: Servlet class com.blenge.blenge.ServletInitializer is not a javax.servlet.Servlet
    at org.eclipse.jetty.servlet.ServletHolder.checkServletType(ServletHolder.java:522)
    at org.eclipse.jetty.servlet.ServletHolder.doStart(ServletHolder.java:381)
    at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:68)
    at org.eclipse.jetty.servlet.ServletHandler.initialize(ServletHandler.java:891)
    at org.eclipse.jetty.servlet.ServletContextHandler.startContext(ServletContextHandler.java:349)
    at org.eclipse.jetty.webapp.WebAppContext.startWebapp(WebAppContext.java:1406)
    at org.eclipse.jetty.webapp.WebAppContext.startContext(WebAppContext.java:1368)
    at org.eclipse.jetty.server.handler.ContextHandler.doStart(ContextHandler.java:778)
    at org.eclipse.jetty.servlet.ServletContextHandler.doStart(ServletContextHandler.java:262)
    at org.eclipse.jetty.webapp.WebAppContext.doStart(WebAppContext.java:522)
    at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:68)
    at org.eclipse.jetty.util.component.ContainerLifeCycle.start(ContainerLifeCycle.java:131)
    at org.eclipse.jetty.util.component.ContainerLifeCycle.doStart(ContainerLifeCycle.java:105)
    at org.eclipse.jetty.server.handler.AbstractHandler.doStart(AbstractHandler.java:61)
    at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:68)
    at org.eclipse.jetty.util.component.ContainerLifeCycle.start(ContainerLifeCycle.java:131)
    at org.eclipse.jetty.server.Server.start(Server.java:422)
    at org.eclipse.jetty.util.component.ContainerLifeCycle.doStart(ContainerLifeCycle.java:105)
    at org.eclipse.jetty.server.handler.AbstractHandler.doStart(AbstractHandler.java:61)
    at org.eclipse.jetty.server.Server.doStart(Server.java:389)
    at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:68)
    at com.google.appengine.tools.development.jetty9.JettyContainerService.startContainer(JettyContainerService.java:346)
    at com.google.appengine.tools.development.AbstractContainerService.startup(AbstractContainerService.java:284)
    at com.google.appengine.tools.development.AutomaticInstanceHolder.startUp(AutomaticInstanceHolder.java:26)
    at com.google.appengine.tools.development.AbstractModule.startup(AbstractModule.java:87)
    at com.google.appengine.tools.development.Modules.startup(Modules.java:105)
    at com.google.appengine.tools.development.DevAppServerImpl.doStart(DevAppServerImpl.java:274)
    at com.google.appengine.tools.development.DevAppServerImpl.access$000(DevAppServerImpl.java:47)
    at com.google.appengine.tools.development.DevAppServerImpl$1.run(DevAppServerImpl.java:219)
    at com.google.appengine.tools.development.DevAppServerImpl$1.run(DevAppServerImpl.java:217)
    at java.security.AccessController.doPrivileged(Native Method)
    at com.google.appengine.tools.development.DevAppServerImpl.start(DevAppServerImpl.java:217)
    at com.google.appengine.tools.development.DevAppServerMain$StartAction.apply(DevAppServerMain.java:368)
    at com.google.appengine.tools.util.Parser$ParseResult.applyArgs(Parser.java:47)
    at com.google.appengine.tools.development.DevAppServerMain.run(DevAppServerMain.java:223)
    at com.google.appengine.tools.development.DevAppServerMain.main(DevAppServerMain.java:214)

I have created ServletInitializer class like in tutorial and example project https://github.com/GoogleCloudPlatform/getting-started-java/blob/master/appengine-standard-java8/springboot-appengine-standard/src/main/java/com/example/appengine/demos/springboot/ServletInitializer.java

There is my build.gradle file https://gist.github.com/Mistic92/576d333df9da7d7efb3e833fd502e430

Also gcloud sdk in version

C:\Users\Lukasz>gcloud version
Google Cloud SDK 172.0.1
alpha 2017.09.15
app-engine-java 1.9.56
app-engine-python 1.9.60
beta 2017.09.15
bq 2.0.26
cloud-datastore-emulator 1.2.1
core 2017.09.21
datalab 20170818
gcloud
gsutil 4.27
kubectl
pubsub-emulator 2017.09.15

Edit1: web.xml file. Also there I get warning that ServletInitializer is not assignable to javax.servlet.Servlet. What should I do?

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://java.sun.com/xml/ns/javaee" version="2.5">

    <servlet>
        <servlet-name>blenge-backend</servlet-name>
        <servlet-class>com.blenge.blenge.ServletInitializer</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>blenge-backend</servlet-name>
        <url-pattern>/</url-pattern>
    </servlet-mapping>

</web-app>

Answer 1

如果您有web.xml，则应指向servlet 3.1规范，而不是2.5。...缺少web.xml，默认为3.1

Answer 2

"class com.blenge.blenge.ServletInitializer is not a javax.servlet.Servlet" seems to indicate an issue with your web.xml

The other possibility is that you have a classloader conflict.