NullPointerException on entityManager in Spring

Question

My problem is that i can't obtain entityManager from LocalContainerEntityManagerFactoryBean. I found a temporary solution instead of this to obtain Factory in source code and then create manager using Factory Instance in code, but i think it's wrong approach for spring apps. There's the code:

ManDAOImpl:

public class ManDAOImpl implements ManDAO{

    //can't obtain EntityManager by that annotation
    @PersistenceContext
    private EntityManager entityManager;

    //It's temporary solution instead of the above, but dont mind
    private EntityManagerFactory emf;

    public void setEmf(EntityManagerFactory emf) {
        this.emf = emf;
    }

    @Override
    public int save(Man man) {
        //temporary solution
//      entityManager = this.emf.createEntityManager();

        entityManager.getTransaction().begin();      //NullPointerException on this line
        entityManager.persist(man);
        entityManager.getTransaction().commit();

        return man.getId();
    }

    @Override
    public void remove(Man man) {
        //temporary solution
//      entityManager = this.emf.createEntityManager();

        entityManager.getTransaction().begin();
        entityManager.remove(man);
        entityManager.getTransaction().commit();
    }

}

My beans in root-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:tx="http://www.springframework.org/schema/tx"
    xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
     http://www.springframework.org/schema/tx 
      http://www.springframework.org/schema/tx/spring-tx-3.2.xsd">

    <bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource"
        >
        <property name="driverClassName" value="com.mysql.jdbc.Driver" />
        <property name="url" value="jdbc:mysql://localhost:3306/tutorialbase" />
        <property name="username" value="tutorial" />
        <property name="password" value="password" />
    </bean>

    <bean id="myEmf" class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
      <property name="dataSource" ref="dataSource" />
      <property name="packagesToScan" value="com.tutorial.myapp.domain" />
      <property name="jpaVendorAdapter">
         <bean class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter" />
      </property>
      <property name="jpaProperties">
         <props>
            <prop key="hibernate.hbm2ddl.auto">create</prop>
            <prop key="hibernate.dialect">org.hibernate.dialect.MySQL5Dialect</prop>
            <prop key="hibernate.current_session_context_class">thread</prop>
            <prop key="hibernate.show_sql">false</prop>
         </props>
      </property>
   </bean>

   <bean id="transactionManager" class="org.springframework.orm.jpa.JpaTransactionManager">
      <property name="entityManagerFactory" ref="myEmf" />
   </bean>
   <tx:annotation-driven />

   <bean id="ManDAO" class="com.tutorial.myapp.daos.ManDAOImpl">
   <property name="emf" ref="myEmf" />
   </bean>

   <bean id="persistenceExceptionTranslationPostProcessor"
      class="org.springframework.dao.annotation.PersistenceExceptionTranslationPostProcessor" />

</beans>

And the console output:

SEVERE: Servlet.service() for servlet [appServlet] in context with path [/myapp] threw exception [Request processing failed; nested exception is java.lang.NullPointerException] with root cause
java.lang.NullPointerException
    at com.tutorial.myapp.daos.ManDAOImpl.save(ManDAOImpl.java:32)
    at com.tutorial.myapp.HomeController.home(HomeController.java:43)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
    at java.lang.reflect.Method.invoke(Unknown Source)
    at org.springframework.web.method.support.InvocableHandlerMethod.invoke(InvocableHandlerMethod.java:213)
    at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:126)
    at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:96)
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:617)
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:578)
    at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:80)
    at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:923)
    at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:852)
    at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:882)
    at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:778)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:622)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:291)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:219)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:106)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:142)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79)
    at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:617)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:88)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:518)
    at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1091)
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:668)
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1521)
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1478)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
    at java.lang.Thread.run(Unknown Source)

In HomeController.java.43 I just trying to save a row:

Man man = new Man();

        man.setFirstName("Janusz");
        man.setLastName("Soft");
        man.setCountry("Polska");

        **manDao.save(man);**

And it's my pom.xml:

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <groupId>com.tutorial</groupId>
    <artifactId>myapp</artifactId>
    <name>Test</name>
    <packaging>war</packaging>
    <version>1.0.0-BUILD-SNAPSHOT</version>
    <properties>
        <java-version>1.6</java-version>
        <org.springframework-version>3.1.1.RELEASE</org.springframework-version>
    </properties>
    <dependencies>
        <!-- Spring -->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context</artifactId>
            <version>${org.springframework-version}</version>
            </dependency>

        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-webmvc</artifactId>
            <version>${org.springframework-version}</version>
        </dependency>

        <!-- Servlet -->
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>jstl</artifactId>
            <version>1.2</version>
        </dependency>

        <dependency>
        <groupId>javax.servlet</groupId>
        <artifactId>javax.servlet-api</artifactId>
        <version>3.1.0</version>
    </dependency>
    <dependency>
        <groupId>javax.servlet</groupId>
        <artifactId>jsp-api</artifactId>
        <version>2.0</version>
    </dependency>
    <dependency>
        <groupId>javax.servlet</groupId>
        <artifactId>jstl</artifactId>
        <version>1.2</version>
    </dependency>

        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-orm</artifactId>
            <version>${org.springframework-version}</version>
        </dependency>

        <!-- Hibernate -->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.36</version>
        </dependency>

        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-jdbc</artifactId>
            <version>${org.springframework-version}</version>
        </dependency>

        <dependency>
            <groupId>org.hibernate</groupId>
            <artifactId>hibernate-entitymanager</artifactId>
            <version>4.3.10.Final</version>
        </dependency>

        <dependency>
    <groupId>javax.ejb</groupId>
    <artifactId>ejb-api</artifactId>
    <version>3.0</version>
</dependency>

Full code of HomeController:

@Controller
public class HomeController {

    @Autowired
    private ManDAO manDao;
    /**
     * Simply selects the home view to render by returning its name.
     */
    @RequestMapping(value = "/", method = RequestMethod.GET)
    public String home(Locale locale, Model model) {

        Date date = new Date();
        DateFormat dateFormat = DateFormat.getDateTimeInstance(DateFormat.LONG, DateFormat.LONG, locale);

        String formattedDate = dateFormat.format(date);

        model.addAttribute("serverTime", formattedDate );

        Man man = new Man();

        man.setFirstName("Janusz");
        man.setLastName("Soft");
        man.setCountry("Polska");

        manDao.save(man);

        return "home";
    }

}

Show us the code of HomeController, in particular, the way you obtain an instance of ManDAO. — JB Nizet
– JB Nizet, Commented Sep 6, 2015 at 9:57

Kong · Accepted Answer · 2015-09-06 10:13:34Z

1

add

<context:annotation-config/>

or

<bean class="org.springframework.orm.jpa.support.PersistenceAnnotationBeanPostProcessor" />

in root-context.xml

answered Sep 6, 2015 at 10:13

Kong

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1 Comment

Kavv Over a year ago

Thanks it sloved my problem

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