exception de l'envoi de contexte initialisé événement à l'auditeur instance de la classe

J'ai cette classe:

public class DatabaseHelper {
    @Autowired
    static UtilService utilService;

    public static void fillEmptyTables(){
        if(!isSkillsInDatabase()){
            utilService.addGeneratedSkill();
        }
        if(!isEventTypesInDatabase()){
            utilService.addGeneratedEventType();
        }
        if(!isEventStatusesInDatabase()){
            utilService.addGeneratedEventStatus();
        }

    }
    public static boolean isSkillsInDatabase(){
        return utilService.getAllSkills().size() != 0; 
    }
    public static boolean isEventStatusesInDatabase(){
        return utilService.getAllEventStatuses().size() != 0; 
    }
    public static boolean isEventTypesInDatabase(){
        return utilService.getAllEventTypes().size() != 0; 
    }
}

et ce listener:

@WebListener
public class ApplicationWebListener implements ServletContextListener {
    @Override
    public void contextDestroyed(ServletContextEvent arg0) {
        System.out.println("ServletContextListener destroyed");
    }

    @Override
    public void contextInitialized(ServletContextEvent arg0) {
        System.out.println("ServletContextListener started");
        DatabaseHelper.fillEmptyTables();
    }
}

Quand je lance mon application, je vois suivantes:

INFO : org.springframework.web.context.ContextLoader - Root WebApplicationContext: initialization completed in 10029 ms
ServletContextListener started
22.10.2013 13:21:16 org.apache.catalina.core.StandardContext listenerStart
SEVERE: Exception sending context initialized event to listener instance of class com.epam.hhsystem.web.controllers.ApplicationWebListener
java.lang.NullPointerException
at com.epam.hhsystem.util.DatabaseHelper.isSkillsInDatabase(DatabaseHelper.java:25)
at com.epam.hhsystem.util.DatabaseHelper.fillEmptyTables(DatabaseHelper.java:13)
at com.epam.hhsystem.web.controllers.ApplicationWebListener.contextInitialized(ApplicationWebListener.java:19)
at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:4887)
at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5381)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1559)
at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1549)
at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:303)
at java.util.concurrent.FutureTask.run(FutureTask.java:138)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
at java.lang.Thread.run(Thread.java:662)
22.10.2013 13:21:16 org.apache.catalina.core.StandardContext startInternal
SEVERE: Error listenerStart

Ce que la cause de ce problème?

Comment résoudre ce problème?

Mise à JOUR

<?xml version="1.0" encoding="UTF-8"?>
<beans:beans xmlns="http://www.springframework.org/schema/mvc"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:beans="http://www.springframework.org/schema/beans"
xmlns:context="http://www.springframework.org/schema/context"
xsi:schemaLocation="http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc.xsd
http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd">
<!-- DispatcherServlet Context: defines this servlet's request-processing infrastructure -->
<!-- Enables the Spring MVC @Controller programming model -->
<annotation-driven />
<!-- Handles HTTP GET requests for /resources/** by efficiently serving up static resources in the ${webappRoot}/resources directory -->
<resources mapping="/resources/**" location="/resources/" />
<!-- Resolves views selected for rendering by @Controllers to .jsp resources in the /WEB-INF/views directory -->
<beans:bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
<beans:property name="prefix" value="/WEB-INF/views/" />
<beans:property name="suffix" value=".jsp" />
</beans:bean>
<context:component-scan base-package="com.epam.hhsystem.web.controllers"/>
</beans:beans>

et ce:

<import resource="classpath:spring/BeanConfig.xml" />
<!-- Файл с настройками Security -->
<import resource="security_config.xml" />

et ce:

<context:annotation-config />
<!--ищем тут разные аннотации (например @service)  -->
<context:component-scan base-package="com.epam.hhsystem.jpa" />
<context:component-scan base-package="com.epam.hhsystem.util" />
<context:component-scan base-package="com.epam.hhsystem.services" />
<context:component-scan base-package="com.epam.hhsystem.web.controllers" />
<!-- Файл с настройками ресурсов для работы с данными (Data Access Resources) -->
<import resource="data.xml" />

que donc.

Mise à JOUR

@WebListener
public class ApplicationWebListener implements ServletContextListener {
@Override
public void contextDestroyed(ServletContextEvent arg0) {
System.out.println("ServletContextListener destroyed");
}
@Override
public void contextInitialized(ServletContextEvent arg0) {
System.out.println("ServletContextListener started");
}
}

ce code fonctionne bien. Quand je lance mon application, je vois

servletContextListener commencé

message

UtilService emplacement:
exception de l'envoi de contexte initialisé événement à l'auditeur instance de la classe

chaîne de configuration:

<context:component-scan base-package="com.epam.hhsystem.services" />

après l'ajout de ce code @classe de Configuration

    @Bean
ApplicationWebListener getApplicationWebListener(){
return new ApplicationWebListener();
}

Je vois la vieille erreur.

Mise à JOUR 2

Je refactoriser mon code pour vos conseils. Je suis confus:

variant1:

   public class MyApplicationListener  implements ApplicationListener<ContextRefreshedEvent> {
@Autowired
UtilService utilService;
public  void fillEmptyTables(){
if(!isSkillsInDatabase()){
utilService.addGeneratedSkill();
}
if(!isEventTypesInDatabase()){
utilService.addGeneratedEventType();
}
if(!isEventStatusesInDatabase()){
utilService.addGeneratedEventStatus();
}
}
public  boolean isSkillsInDatabase(){
return utilService.getAllSkills().size() != 0; 
}
public  boolean isEventStatusesInDatabase(){
return utilService.getAllEventStatuses().size() != 0; 
}
public  boolean isEventTypesInDatabase(){
return utilService.getAllEventTypes().size() != 0; 
}    
@Override
public void onApplicationEvent(ContextRefreshedEvent event) {
fillEmptyTables();
}
}

Cette variante fonctionne bien, mais c'est l'architecture d'horreur

variante 2:

public class MyApplicationListener  implements ApplicationListener<ContextRefreshedEvent> {
@Override
public void onApplicationEvent(ContextRefreshedEvent event) {
DatabaseHelper.fillEmptyTables();
}
}

Je vois des vieux stacktrace.

pourquoi?

  • Postez votre fichier de configuration spring