@Autowired annotation returns null

Question

When I develop in the Spring Framework, I wanted to get an access to DB using mybatis on the specific class, here is problem.

     public class ScheduleManager {

            private Scheduler scheduler;

            @Autowired
            private TriggerService triggerService;

            public void doit() {

                    System.out.println(triggerService);

            }

        }

At here, value of triggerService is null. I think triggerService was not autowired.

But it is autowired at this class.

 @Controller
    public class TestController {

        @Autowired
        private TriggerService triggerService;

        @RequestMapping("/scheduletest")
        public String scheduleTest() {

            System.out.println(triggerService);

            ScheduleManager sm = new ScheduleManager();

            sm.doit();
        }
    }

this code print some value not null.

dispatcher-servlet.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"

       xsi:schemaLocation="http://www.springframework.org/schema/beans
             http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
             http://www.springframework.org/schema/context
             http://www.springframework.org/schema/context/spring-context-3.0.xsd">

    <context:annotation-config/>

    <context:component-scan base-package="com.scheduler"/>

    <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
        <property name="prefix" value="/WEB-INF/views/"/>
        <property name="suffix" value=".jsp"/>
        <property name="contentType" value="text/html;charset=UTF-8"/>
        <property name="order" value="0"/>
    </bean>

</beans>

TriggerService interface

@Service
public interface TriggerService {
    public List<Trigger> getAll();
}

Why does this problem appear?

Where do you use the ScheduleManager? It doesn't have any Component annotation on it, so Spring doesn't know it. — dunni, May 13 '16 at 08:36
I used ScheduleManager instance at the TestController class. I edited my question. — Moon Taejin, May 13 '16 at 08:38
The ScheduleManager class doesn't have a constructor which takes a TriggerService as parameter. Please post valid code. — dunni, May 13 '16 at 08:41

score 2 · Accepted Answer · answered May 13 '16 at 08:46

You create the ScheduleManager instance by yourself:

ScheduleManager sm = new ScheduleManager();

So Spring doesn't know about this object and doesn't do any autowiring. To resolve this, add the @Component annotation to ScheduleManager and let it also inject in the controller:

@Autowired
private ScheduleManager scheduleManager;

score 0 · Answer 2 · answered May 13 '16 at 08:31

0

Your TriggerService is only an Interface, how could spring find the acutual implementation.

remove @Service from TriggerService and add it to one of the implementation of TriggerService will fix your problem

answered May 13 '16 at 08:31

Jaiwo99

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As you said, I remove @Service from TriggerService. But, I have to use MyBatis and using interface is the format of MyBatis. How can I implement this interface, if you have answer, tell me please. – Moon Taejin May 13 '16 at 08:44

@Autowired annotation returns null

2 Answers2

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