Spring boot - configure EntityManager - spring-boot

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