Unable to Inject DAO class in Spring BO

Question

I am unable to inject my DAO class in Spring MVC: This is my DAO class:

package com.pankaj.bookslibrary.dao;

@Component
public class BooksLibraryDAO 
{
    @PersistenceContext
    private EntityManager em;

    public void saveBook(Book book)
    {
        em.persist(book);
    }
}

This is my BO class which calls DAO:

package com.pankaj.bookslibrary.controller;

@Service
public class BooksLibraryBO 
{
    @Autowired
    private BooksLibraryDAO booksLibraryDAO; 

    public void saveBook(Book book)
    {
        booksLibraryDAO.saveBook(book);
    }

The above line gives NullPointerException as booksLibraryDAO is null. Here are the relevant lines from my dispatcherServlet config file:

<beans xmlns=...3.0.xsd">

    <context:component-scan base-package="com.pankaj.bookslibrary" />
    <context:annotation-config/>

    <bean id="dataSource"....</bean>

    <bean id="entityManagerFactory"
        class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
        <property name="persistenceXmlLocation" value="classpath:META-INF/persistence.xml" />
        <property name="persistenceUnitName" value="BooksLibrary_PersistenceUnit" />
        <property name="dataSource" ref="dataSource" />
        <property name="jpaVendorAdapter">
            <bean class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter">
                <property name="databasePlatform" value="org.hibernate.dialect.MySQL5InnoDBDialect" />
                <property name="showSql" value="false" />
                <property name="generateDdl" value="true" />
            </bean>
        </property>
    </bean>


    <bean id="transactionManagerNonJTA" class="org.springframework.orm.jpa.JpaTransactionManager">
        <property name="entityManagerFactory" ref="entityManagerFactory" />
        <property name="defaultTimeout" value="1800"></property>
    </bean>
    <tx:annotation-driven transaction-manager="transactionManagerNonJTA" />

I am not sure what I have missed. This is how I am making a call from the controller:

BooksLibraryBO bo = new BooksLibraryBO();
bo.saveBook(book);

You are creating a new instance yourself, don't do that, inject the BO as well in the controller. — M. Deinum, Feb 02 '16 at 06:09

score 1 · Answer 1 · answered Feb 02 '16 at 07:08

The packages the classes are in differs from the package you scan for annotations. Add the packages to the list of base-packages to scan for!
As M.Deinum explained, you are creating the BooksLibraryBO yourself, spring do not know that instances and will not process the annotations.

Unable to Inject DAO class in Spring BO

1 Answers1