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JPA with Spring MVC Configures Using Annotations

I am trying to create a Spring MVC application using JPA for my persistence level. Unfortunately, I was getting a NullPointerException when accessing the EntityManager as Spring did not seem to throw it. My configuration is based on annotations using @EnableWebMvc. After some searching, I added @Transactional to my DAO and @EnableTransactionManagement to my @Configuration class. Then I received a message about the lack of a data source. Presumably, a class with @EnableTransactionManagement should implement TransactionManagementConfigurer. However, I am having trouble figuring out how to create a DataSource, and also why it cannot get it from my persistence.xml.

I would really appreciate any help in trying to get the EntityManager introduced in my DAO.

My @Configuration class

@Configuration
@EnableWebMvc
@EnableTransactionManagement
@ComponentScan("com.example.myapp")
public class MvcConfig extends WebMvcConfigurerAdapter 
        implements TransactionManagementConfigurer {

private static final boolean CACHE_ENABLED = true;
private static final String TEMPLATE_PATH = "/WEB-INF/freemarker";
private static final String TEMPLATE_SUFFIX = ".ftl";

private static final Logger LOG = Logger.getLogger( MvcConfig.class );

@Override
public void addResourceHandlers( ResourceHandlerRegistry registry ) {
    registry.addResourceHandler( "/stylesheets/**" ).addResourceLocations( "/stylesheets/" );
}

@Bean
public FreeMarkerConfigurer configureFreeMarker() {
    final FreeMarkerConfigurer configurer = new FreeMarkerConfigurer();
    configurer.setTemplateLoaderPath( TEMPLATE_PATH );
    return configurer;
}

@Bean
public ViewResolver configureViewResolver() {
    final FreeMarkerViewResolver resolver = new FreeMarkerViewResolver();
    resolver.setCache( CACHE_ENABLED );
    resolver.setSuffix( TEMPLATE_SUFFIX );
    return resolver;
}

@Bean
@Override
public PlatformTransactionManager annotationDrivenTransactionManager() {
    return new DataSourceTransactionManager();
}

}

My dao

@Component
@Transactional
public class MyDAO {

    private static final Logger LOG = Logger.getLogger( MyDAO.class );

    @PersistenceContext
    private EntityManager entityManager;

    public MyClass getMyClass() {
        LOG.debug( "getMyClass()" );
        final CriteriaQuery<MyClass> query = criteriaBuilder.createQuery( MyClass.class );
        // more code here, but it breaks by this point
        return myData;
    }

}

My updated code

, . EntityManager . . , RESOURCE_LOCAL, , JTA. @Transactional DAO, ", ", - , . , ( , ). , , , , db-. , , , . , , javax.transaction.RollbackException. , , - AOP.

@Configuration

@Configuration
@EnableWebMvc
@EnableTransactionManagement
@ComponentScan("com.example.myapp")
public class MvcConfig extends WebMvcConfigurerAdapter {

private static final boolean CACHE_ENABLED = true;
private static final String TEMPLATE_PATH = "/WEB-INF/freemarker";
private static final String TEMPLATE_SUFFIX = ".ftl";

private static final Logger LOG = Logger.getLogger( MvcConfig.class );

@Override
public void addResourceHandlers( ResourceHandlerRegistry registry ) {
    registry.addResourceHandler( "/stylesheets/**" ).addResourceLocations( "/stylesheets/" );
}

@Bean
public FreeMarkerConfigurer configureFreeMarker() {
    final FreeMarkerConfigurer configurer = new FreeMarkerConfigurer();
    configurer.setTemplateLoaderPath( TEMPLATE_PATH );
    return configurer;
}

@Bean
public ViewResolver configureViewResolver() {
    final FreeMarkerViewResolver resolver = new FreeMarkerViewResolver();
    resolver.setCache( CACHE_ENABLED );
    resolver.setSuffix( TEMPLATE_SUFFIX );
    return resolver;
}

@Bean
public PlatformTransactionManager transactionManager() {
    return new JtaTransactionManager();
}

@Bean
public AbstractEntityManagerFactoryBean entityManagerFactoryBean() {
    LocalEntityManagerFactoryBean factory = new LocalEntityManagerFactoryBean();
    factory.setPersistenceUnitName( "my_db" );
    return factory;
}

}
+5
2

TransactionManagerConfigurer. JPA ( Hibernate). .

    @Bean
    public LocalContainerEntityManagerFactoryBean entityManagerFactoryBean() {
        LocalContainerEntityManagerFactoryBean factoryBean = 
                new LocalContainerEntityManagerFactoryBean();

        factoryBean.setDataSource(dataSource());
        factoryBean.setPackagesToScan(new String[] {"com.dimasco.springjpa.domain"});

        HibernateJpaVendorAdapter vendorAdapter = new HibernateJpaVendorAdapter();
        vendorAdapter.setShowSql(true);
        //vendorAdapter.setGenerateDdl(generateDdl)

        factoryBean.setJpaVendorAdapter(vendorAdapter);

        Properties additionalProperties = new Properties();
        additionalProperties.put("hibernate.hbm2ddl.auto", "update");

        factoryBean.setJpaProperties(additionalProperties);


        return factoryBean;
    }

    @Bean
    public DataSource dataSource() {
        final ComboPooledDataSource dataSource = new ComboPooledDataSource();

        try {
            dataSource.setDriverClass(driverClass);
        } catch (PropertyVetoException e) {
            throw new RuntimeException(e);
        }

        dataSource.setJdbcUrl(jdbcUrl);
        dataSource.setUser(user);
        dataSource.setPassword(password);
        dataSource.setMinPoolSize(3);
        dataSource.setMaxPoolSize(15);
        dataSource.setDebugUnreturnedConnectionStackTraces(true);

        return dataSource;
    }

    @Bean
    public PlatformTransactionManager transactionManager() {
        JpaTransactionManager transactionManager = new JpaTransactionManager();
        transactionManager.setEntityManagerFactory(entityManagerFactoryBean().getObject());

        return transactionManager;
    }

    @Bean
    public PersistenceExceptionTranslationPostProcessor exceptionTranslation(){
        return new PersistenceExceptionTranslationPostProcessor();
    }

, )

EDIT:

JNDI:

@Bean
public DataSource dataSource() throws Exception {
   Context ctx = new InitialContext();
   return (DataSource) ctx.lookup("java:comp/env/jdbc/datasource");
}

. JndiDatasourceConfig.

2: ahve persistence.xml , :

<persistence version="2.0" xmlns="http://java.sun.com/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_2_0.xsd">
    <persistence-unit name="JPA_And_Spring_Test">
    </persistence-unit>
</persistence>

java.

+9

, XML:

https://github.com/springinpractice/sip13/blob/master/helpdesk/src/main/resources/spring/beans-repo.xml

Spring Data JPA, .

 @PersistenceContext private EntityManager entityManager;

( Spring Data JPA, DAO .)

: DAO @Repository @Component. , @Repository .

+1

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