Spring Autowiring Service doesn't work in my Controller

Question

i've problems in order to autowire a service in my controller. I've this error:

org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'myController': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: private es.unican.meteo.service.UserService es.unican.meteo.controller.MyController.userService; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No matching bean of type [es.unican.meteo.service.UserService] found for dependency: expected at least 1 bean which qualifies as autowire candidate for this dependency. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}

It seems that the userService is not registered, so that, the controller can't get the bean. I thought that my config was ok because it works with the tests. In the tests i have this:

ClassPathXmlApplicationContext("/WEB-INF/app-config.xml");

and i can get the bean ok from the ApplicationContext.xml

My package structure is the following:

es.unican.meteo.controller

|---- MyController.java

es.unican.meteo.service

|---- UserService.java

es.unican.meteo.service.impl

|---- UserServiceImpl.java

.....

WebContent/WEB-INF

|---- MyDispatcherServlet-servlet.xml

|---- app-config.xml

|---- web.xml

.....

The clases:

== UserServiceImpl.java ==

@Service
public class UserServiceImpl implements UserService{

    @Autowired
    private UserMapper userMapper;

    public void setUserMapper(UserMapper userMapper) {
        this.userMapper = userMapper;
    }

== MyController.java ==

@Controller
public class MyController {

     @Autowired
     private UserService userService;

     @RequestMapping(method=RequestMethod.GET, value="/home")
     public String handleRequest(){
      return "welcome";
     }

     @RequestMapping(method=RequestMethod.GET, value="/getUsers")
     public @ResponseBody List<User> getUsersInJSON(){
      return userService.getUsers();
     }
}

== web.xml ==

<display-name>Spring MVC</display-name>

 <servlet>
  <servlet-name>MyDispatcherServlet</servlet-name>
  <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
 </servlet>

 <servlet-mapping>
  <servlet-name>MyDispatcherServlet</servlet-name>
  <url-pattern>*.go</url-pattern>
 </servlet-mapping>
</web-app>

== app-config.xml ===

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:context="http://www.springframework.org/schema/context"
    xmlns:p="http://www.springframework.org/schema/p"
    xmlns:mvc="http://www.springframework.org/schema/mvc"
    xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.1.xsd
        http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.1.xsd
        http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-3.1.xsd">


   <!-- Scans the classpath of this application for @Components to deploy as beans -->
   <context:component-scan base-package="es.unican.meteo" />

   <!-- Configures the @Controller programming model -->
   <mvc:annotation-driven/>

   <bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource"
    p:driverClassName="org.apache.derby.jdbc.EmbeddedDriver"
    p:url="jdbc:derby:C:\tools\derbydb"
    p:connectionProperties=""
    p:username="APP"
    p:password="" />

    <bean id="transactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
        <property name="dataSource" ref="dataSource"/>
    </bean>

    <bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
        <property name="dataSource" ref="dataSource" />
        <property name="configLocation" value="/mybatis-config.xml" />
    </bean> 

    <bean id="usersMapper" class="org.mybatis.spring.mapper.MapperFactoryBean">
        <property name="mapperInterface" value="es.unican.meteo.dao.UserMapper" />
        <property name="sqlSessionFactory" ref="sqlSessionFactory" />
    </bean> 

    <bean id="rolesMapper" class="org.mybatis.spring.mapper.MapperFactoryBean">
        <property name="mapperInterface" value="es.unican.meteo.dao.RoleMapper" />
        <property name="sqlSessionFactory" ref="sqlSessionFactory" />
    </bean> 

</beans>

== MyDispatcherServlet.xml ==

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 xmlns:context="http://www.springframework.org/schema/context"
 xmlns:mvc="http://www.springframework.org/schema/mvc"
 xsi:schemaLocation="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-3.1.xsd
  http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-3.1.xsd">

 <!-- Enabling Spring beans auto-discovery -->
 <context:component-scan base-package="es.unican.meteo.controller" />

 <!-- Enabling Spring MVC configuration through annotations -->
 <mvc:annotation-driven />

 <!-- Defining which view resolver to use -->
 <bean class= "org.springframework.web.servlet.view.InternalResourceViewResolver" > 
  <property name="prefix" value="/WEB-INF/views/" /> 
  <property name="suffix" value=".jsp" /> 
 </bean>

Spring mvc logger trace:

19:38:54,119 DEBUG http-8080-1 support.DefaultListableBeanFactory:430 - Creating instance of bean 'myController'
19:38:54,170 DEBUG http-8080-1 annotation.InjectionMetadata:60 - Found injected element on class [es.unican.meteo.controller.MyController]: AutowiredFieldElement for private es.unican.meteo.service.UserService es.unican.meteo.controller.MyController.userService
19:38:54,174 DEBUG http-8080-1 support.DefaultListableBeanFactory:504 - Eagerly caching bean 'myController' to allow for resolving potential circular references
19:38:54,206 DEBUG http-8080-1 annotation.InjectionMetadata:85 - Processing injected method of bean 'myController': AutowiredFieldElement for private es.unican.meteo.service.UserService es.unican.meteo.controller.MyController.userService
19:38:54,224 DEBUG http-8080-1 support.DefaultListableBeanFactory:217 - Creating shared instance of singleton bean 'userServiceImpl'
19:38:54,226 DEBUG http-8080-1 support.DefaultListableBeanFactory:430 - Creating instance of bean 'userServiceImpl'
19:38:54,234 DEBUG http-8080-1 annotation.InjectionMetadata:60 - Found injected element on class [es.unican.meteo.service.impl.UserServiceImpl]: AutowiredFieldElement for private es.unican.meteo.dao.UserMapper es.unican.meteo.service.impl.UserServiceImpl.userMapper
19:38:54,237 DEBUG http-8080-1 support.DefaultListableBeanFactory:504 - Eagerly caching bean 'userServiceImpl' to allow for resolving potential circular references
19:38:54,256 DEBUG http-8080-1 annotation.InjectionMetadata:85 - Processing injected method of bean 'userServiceImpl': AutowiredFieldElement for private es.unican.meteo.dao.UserMapper es.unican.meteo.service.impl.UserServiceImpl.userMapper
19:38:54,268  INFO http-8080-1 support.DefaultListableBeanFactory:433 - Destroying singletons in org.springframework.beans.factory.support.DefaultListableBeanFactory@56088b29: defining beans [myController,roleService,userServiceImpl,org.springframework.context.annotation.internalConfigurationAnnotationProcessor,org.springframework.context.annotation.internalAutowiredAnnotationProcessor,org.springframework.context.annotation.internalRequiredAnnotationProcessor,org.springframework.context.annotation.internalCommonAnnotationProcessor,org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping#0,org.springframework.format.support.FormattingConversionServiceFactoryBean#0,org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter#0,org.springframework.web.servlet.handler.MappedInterceptor#0,org.springframework.web.servlet.mvc.method.annotation.ExceptionHandlerExceptionResolver#0,org.springframework.web.servlet.mvc.annotation.ResponseStatusExceptionResolver#0,org.springframework.web.servlet.mvc.support.DefaultHandlerExceptionResolver#0,org.springframework.web.servlet.handler.BeanNameUrlHandlerMapping,org.springframework.web.servlet.mvc.HttpRequestHandlerAdapter,org.springframework.web.servlet.mvc.SimpleControllerHandlerAdapter,org.springframework.web.servlet.view.InternalResourceViewResolver#0,org.springframework.context.annotation.ConfigurationClassPostProcessor$ImportAwareBeanPostProcessor#0]; root of factory hierarchy
19:38:54,279 ERROR http-8080-1 servlet.DispatcherServlet:457 - Context initialization failed

I've reviewed some questions about this topic but i don't find a solution to my problem. Maybe i'm skipping something but i don't know certainly. I tried to change the component-scan with no results.

When i try to access to /SPRING-MVC/getUsers.go appears those errors.

I don't know if the beans must be placed in app-config (applicationContext) or in the servlet.xml because it is a little bit confusing...

Thank you

Answer 1

Your configuration is very strange...

First rule out the obvious

I don't see root web application context configuration in your web.xml. Could it be that you forgot to add this piece of code?

<context-param>
    <param-name>contextConfigLocation</param-name>
    <param-value>
        WEB-INF/app-config.xml
    </param-value>
</context-param>

<listener>
    <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
</listener>

Now a little bit of theory

Bit of Spring theory - Spring uses application context hierarchy for web applications:

• top level web application context is loaded by ContextLoaderListener
• then there are separate contexts for each DispatcherServlet instances

When a new bean is being instantiated, it can get dependencies either from the context where it is being defined or from parent context. This makes possible to define common beans in the root context (services, DAO, ...) and have the request handling beans in servlet application contexts as each servlet can have its own set of controllers, view handers, ...

Last, but not least - your errors

You are configuring MVC in your root context. That is just wrong. Remove the <mvc: context from there.

You are also registering your controllers in the root context via the <context:component-scan> on your base package. Make the component scan just on the services package or separate your classes into two top level packages core (for the root beans) and servlet (for servlet beans).

Answer 2

Make sure that your UserServiceImpl is in same package as defined in context:component-scan. If it's not, spring will not be able to detect it. Also, try removing value attribute from UserServiceImpl definition, since there is only 1 bean of that type. Spring will be able to autowire it by type.