Spring @Autowired comes as null

Wild Goat Published at Dev

Wild Goat

I have @Component, A, which AutoWires a class which contains simple configurations for class A. I've created a bin for configuration file. But for some reason it comes as null. Could you please help me to find out the problem?

@Component
public class SearchEngineDriver {

    @Autowired(required = true)
    private EngineContext context;


    public SearchEngineDriver(){
         String clusterName = context.getClusterName();
    }
}


public class EngineContext {

    private String clusterName;

    public EngineContext(String clusterName){
        this.clusterName = clusterName;
    }

    public String getClusterName(){
        return this.clusterName;
    }
}

3rd class.

    @Autowired
    private SearchEngineDriver searchEngineDriver;

mvc-dispatcher-servlet.xml

<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:mvc="http://www.springframework.org/schema/mvc"
       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
       http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-3.0.xsd">


<context:component-scan base-package="org.electronsoftware" />
    <mvc:annotation-driven/>
    <mvc:resources mapping="/resources/**" location="/resources/" />

    <import resource="classpath*:/application-context.xml"/>

    <bean
            class="org.springframework.web.servlet.view.InternalResourceViewResolver">
        <property name="prefix">
            <value>/</value>
        </property>
        <property name="suffix">
            <value>.jsp</value>
        </property>
    </bean>

</beans>

application-context.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.xsd
       http://www.springframework.org/schema/context
        http://www.springframework.org/schema/context/spring-context-3.2.xsd">


    <context:property-placeholder location="classpath:application.properties"/>


    <bean id="searchEngineContext" class="org.electronsoftware.KGB.search.context.EngineContext" >
        <constructor-arg value="${kgb.search.engine.clustername}"/>
    </bean>

</beans>

Marko Topolnik

You are accessing the autowired field from the constructor. At the time the constructor runs, Spring has not yet got the chance to initialize the field. Instead use a @PostConstruct method to perform logic which depends on the autowired value.

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