Spring boot - configure EntityManager

Question

I was using Google guice in my project and now I tried to convert the framework to SpringBoot totally.

I configured the Bean for persistence.xml like below in

@Autowired @Bean(name = "transactionManager") public LocalContainerEntityManagerFactoryBean entityManagerFactory() {     LocalContainerEntityManagerFactoryBean lEMF =  new LocalContainerEntityManagerFactoryBean();     lEMF.setPersistenceUnitName("leaseManagementPU");     lEMF.setPersistenceXmlLocation("persistence.xml");     return lEMF; } 

Now I need to configure(Inject) EntityManager em, to do JPA operations like em.persist(), em.find etc... How do I configure, also someone try to explain this with sample code

Answer 1

With Spring Boot its not necessary to have any config file like persistence.xml. You can configure with annotations Just configure your DB config for JPA in the

application.properties

spring.datasource.driverClassName=oracle.jdbc.driver.OracleDriver spring.datasource.url=jdbc:oracle:thin:@DB... spring.datasource.username=username spring.datasource.password=pass  spring.jpa.database-platform=org.hibernate.dialect.... spring.jpa.show-sql=true 

Then you can use CrudRepository provided by Spring where you have standard CRUD transaction methods. There you can also implement your own SQL's like JPQL.

@Transactional public interface ObjectRepository extends CrudRepository<Object, Long> { ... } 

And if you still need to use the Entity Manager you can create another class.

public class ObjectRepositoryImpl implements ObjectCustomMethods{      @PersistenceContext     private EntityManager em;  } 

This should be in your pom.xml

<parent>     <groupId>org.springframework.boot</groupId>     <artifactId>spring-boot-starter-parent</artifactId>     <version>1.2.5.RELEASE</version> </parent>  <dependencies>     <dependency>         <groupId>org.springframework.boot</groupId>         <artifactId>spring-boot-starter-data-jpa</artifactId>     </dependency>     <dependency>         <groupId>org.springframework</groupId>         <artifactId>spring-orm</artifactId>     </dependency>     <dependency>         <groupId>org.hibernate</groupId>         <artifactId>hibernate-core</artifactId>         <version>4.3.11.Final</version>     </dependency> </dependencies> 

Answer 2

Hmmm you can find lot of examples for configuring spring framework. Anyways here is a sample

@Configuration @Import({PersistenceConfig.class}) @ComponentScan(basePackageClasses = {      ServiceMarker.class,     RepositoryMarker.class } ) public class AppConfig {  } 

PersistenceConfig

@Configuration @PropertySource(value = { "classpath:database/jdbc.properties" }) @EnableTransactionManagement public class PersistenceConfig {      private static final String PROPERTY_NAME_HIBERNATE_DIALECT = "hibernate.dialect";     private static final String PROPERTY_NAME_HIBERNATE_MAX_FETCH_DEPTH = "hibernate.max_fetch_depth";     private static final String PROPERTY_NAME_HIBERNATE_JDBC_FETCH_SIZE = "hibernate.jdbc.fetch_size";     private static final String PROPERTY_NAME_HIBERNATE_JDBC_BATCH_SIZE = "hibernate.jdbc.batch_size";     private static final String PROPERTY_NAME_HIBERNATE_SHOW_SQL = "hibernate.show_sql";     private static final String[] ENTITYMANAGER_PACKAGES_TO_SCAN = {"a.b.c.entities", "a.b.c.converters"};      @Autowired     private Environment env;       @Bean(destroyMethod = "close")      public DataSource dataSource() {          BasicDataSource dataSource = new BasicDataSource();          dataSource.setDriverClassName(env.getProperty("jdbc.driverClassName"));          dataSource.setUrl(env.getProperty("jdbc.url"));          dataSource.setUsername(env.getProperty("jdbc.username"));          dataSource.setPassword(env.getProperty("jdbc.password"));          return dataSource;      }       @Bean      public JpaTransactionManager jpaTransactionManager() {          JpaTransactionManager transactionManager = new JpaTransactionManager();          transactionManager.setEntityManagerFactory(entityManagerFactoryBean().getObject());          return transactionManager;      }      private HibernateJpaVendorAdapter vendorAdaptor() {          HibernateJpaVendorAdapter vendorAdapter = new HibernateJpaVendorAdapter();          vendorAdapter.setShowSql(true);          return vendorAdapter;     }      @Bean     public LocalContainerEntityManagerFactoryBean entityManagerFactoryBean() {           LocalContainerEntityManagerFactoryBean entityManagerFactoryBean = new LocalContainerEntityManagerFactoryBean();          entityManagerFactoryBean.setJpaVendorAdapter(vendorAdaptor());          entityManagerFactoryBean.setDataSource(dataSource());          entityManagerFactoryBean.setPersistenceProviderClass(HibernatePersistenceProvider.class);          entityManagerFactoryBean.setPackagesToScan(ENTITYMANAGER_PACKAGES_TO_SCAN);                       entityManagerFactoryBean.setJpaProperties(jpaHibernateProperties());           return entityManagerFactoryBean;      }       private Properties jpaHibernateProperties() {           Properties properties = new Properties();           properties.put(PROPERTY_NAME_HIBERNATE_MAX_FETCH_DEPTH, env.getProperty(PROPERTY_NAME_HIBERNATE_MAX_FETCH_DEPTH));          properties.put(PROPERTY_NAME_HIBERNATE_JDBC_FETCH_SIZE, env.getProperty(PROPERTY_NAME_HIBERNATE_JDBC_FETCH_SIZE));          properties.put(PROPERTY_NAME_HIBERNATE_JDBC_BATCH_SIZE, env.getProperty(PROPERTY_NAME_HIBERNATE_JDBC_BATCH_SIZE));          properties.put(PROPERTY_NAME_HIBERNATE_SHOW_SQL, env.getProperty(PROPERTY_NAME_HIBERNATE_SHOW_SQL));           properties.put(AvailableSettings.SCHEMA_GEN_DATABASE_ACTION, "none");          properties.put(AvailableSettings.USE_CLASS_ENHANCER, "false");                return properties;             }  } 

Main

public static void main(String[] args) {      try (GenericApplicationContext springContext = new AnnotationConfigApplicationContext(AppConfig.class)) {         MyService myService = springContext.getBean(MyServiceImpl.class);         try {             myService.handleProcess(fromDate, toDate);         } catch (Exception e) {             logger.error("Exception occurs", e);             myService.handleException(fromDate, toDate, e);         }     } catch (Exception e) {         logger.error("Exception occurs in loading Spring context: ", e);     } } 

MyService

@Service public class MyServiceImpl implements MyService {      @Inject     private MyDao myDao;      @Override     public void handleProcess(String fromDate, String toDate) {         List<Student> myList = myDao.select(fromDate, toDate);     } } 

MyDaoImpl

@Repository @Transactional public class MyDaoImpl implements MyDao {      @PersistenceContext     private EntityManager entityManager;      public Student select(String fromDate, String toDate){          TypedQuery<Student> query = entityManager.createNamedQuery("Student.findByKey", Student.class);         query.setParameter("fromDate", fromDate);         query.setParameter("toDate", toDate);         List<Student> list = query.getResultList();         return CollectionUtils.isEmpty(list) ? null : list;     }  } 

Assuming maven project: Properties file should be in src/main/resources/database folder

jdbc.properties file

jdbc.driverClassName=com.mysql.jdbc.Driver jdbc.url=your db url jdbc.username=your Username jdbc.password=Your password  hibernate.max_fetch_depth = 3 hibernate.jdbc.fetch_size = 50 hibernate.jdbc.batch_size = 10 hibernate.show_sql = true 

ServiceMarker and RepositoryMarker are just empty interfaces in your service or repository impl package.

Let's say you have package name a.b.c.service.impl. MyServiceImpl is in this package and so is ServiceMarker.

public interface ServiceMarker {  } 

Same for repository marker. Let's say you have a.b.c.repository.impl or a.b.c.dao.impl package name. Then MyDaoImpl is in this this package and also Repositorymarker

public interface RepositoryMarker {  } 

a.b.c.entities.Student

//dummy class and dummy query @Entity @NamedQueries({ @NamedQuery(name="Student.findByKey", query="select s from Student s where s.fromDate=:fromDate" and s.toDate = :toDate) }) public class Student implements Serializable {      private LocalDateTime fromDate;     private LocalDateTime toDate;      //getters setters  } 

a.b.c.converters

@Converter(autoApply = true) public class LocalDateTimeConverter implements AttributeConverter<LocalDateTime, Timestamp> {      @Override     public Timestamp convertToDatabaseColumn(LocalDateTime dateTime) {          if (dateTime == null) {             return null;         }         return Timestamp.valueOf(dateTime);     }      @Override     public LocalDateTime convertToEntityAttribute(Timestamp timestamp) {          if (timestamp == null) {             return null;         }             return timestamp.toLocalDateTime();     } } 

pom.xml

<properties>     <java-version>1.8</java-version>     <org.springframework-version>4.2.1.RELEASE</org.springframework-version>     <hibernate-entitymanager.version>5.0.2.Final</hibernate-entitymanager.version>     <commons-dbcp2.version>2.1.1</commons-dbcp2.version>     <mysql-connector-java.version>5.1.36</mysql-connector-java.version>      <junit.version>4.12</junit.version>  </properties>  <dependencies>     <dependency>         <groupId>junit</groupId>         <artifactId>junit</artifactId>         <version>${junit.version}</version>         <scope>test</scope>     </dependency>      <!-- Spring -->     <dependency>         <groupId>org.springframework</groupId>         <artifactId>spring-context</artifactId>         <version>${org.springframework.version}</version>     </dependency>      <dependency>         <groupId>org.springframework</groupId>         <artifactId>spring-jdbc</artifactId>         <version>${org.springframework.version}</version>     </dependency>      <dependency>         <groupId>javax.inject</groupId>         <artifactId>javax.inject</artifactId>         <version>1</version>         <scope>compile</scope>     </dependency>      <dependency>         <groupId>org.springframework</groupId>         <artifactId>spring-tx</artifactId>         <version>${org.springframework-version}</version>     </dependency>      <dependency>         <groupId>org.springframework</groupId>         <artifactId>spring-orm</artifactId>         <version>${org.springframework-version}</version>     </dependency>      <dependency>         <groupId>org.hibernate</groupId>         <artifactId>hibernate-entitymanager</artifactId>         <version>${hibernate-entitymanager.version}</version>     </dependency>      <dependency>         <groupId>mysql</groupId>         <artifactId>mysql-connector-java</artifactId>         <version>${mysql-connector-java.version}</version>     </dependency>      <dependency>         <groupId>org.apache.commons</groupId>         <artifactId>commons-dbcp2</artifactId>         <version>${commons-dbcp2.version}</version>     </dependency> </dependencies>  <build>      <finalName>${project.artifactId}</finalName>      <plugins>          <plugin>             <groupId>org.apache.maven.plugins</groupId>             <artifactId>maven-compiler-plugin</artifactId>             <version>3.3</version>             <configuration>                 <source>${java-version}</source>                 <target>${java-version}</target>                 <compilerArgument>-Xlint:all</compilerArgument>                 <showWarnings>true</showWarnings>                 <showDeprecation>true</showDeprecation>             </configuration>         </plugin>      </plugins> </build> 

Hope it helps. Thanks