Java

JPA

This is a rough overview of configuration JPA with hibernate.

Pom.xml (Maven)

MySQL

	<!-- https://mvnrepository.com/artifact/mysql/mysql-connector-java -->
	<dependency>
    	<groupId>mysql</groupId>
    	<artifactId>mysql-connector-java</artifactId>
    	<version>8.0.20</version>
	</dependency>

Hibernate

	<!-- https://mvnrepository.com/artifact/org.hibernate/hibernate-entitymanager -->
	<dependency>
    	<groupId>org.hibernate</groupId>
    	<artifactId>hibernate-entitymanager</artifactId>
    	<version>6.0.0.Alpha5</version>
    	<type>pom</type>
	</dependency>

Jta

	<!-- https://mvnrepository.com/artifact/javax.transaction/jta -->
	<dependency>
    	<groupId>javax.transaction</groupId>
    	<artifactId>jta</artifactId>
    	<version>1.1</version>
	</dependency>

Spring Orm/JDBC

	<!-- https://mvnrepository.com/artifact/org.springframework/spring-jdbc -->
	<dependency>
    	<groupId>org.springframework</groupId>
    	<artifactId>spring-jdbc</artifactId>
    	<version>5.2.6.RELEASE</version>
	</dependency>

	<!-- https://mvnrepository.com/artifact/org.springframework/spring-orm -->
	<dependency>
    	<groupId>org.springframework</groupId>
    	<artifactId>spring-orm</artifactId>
    	<version>5.2.6.RELEASE</version>
	</dependency>

Persistence.xml

 <persistence 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_2.xsd" 
  version="2.2">
  <persistence-unit name="punit">
  </persistence-unit>	
 </persistence>

Web.xml

Started by the container to listen for context events

    <context-param>
    	<param-name>contextConfigLocation</param-name>
    	<param-value>classPath:/jpaContext.xml</param-value>
    </context-param>
    
    <listener>
    	<listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
    </listener>

JpaContext.xml

Initial context

 <?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 "
	xmlns:context="http://www.springframework.org/schema/context"
	xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
		http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.2.xsd
		http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-4.3.xsd">

	<context-annotation-config />
	<bean class="org.springframework.orm.jpa.support.PersistenceAnnotationBeanPostProcessor" />

 </beans>

Adding EntityManager and Properties

	<bean id="entityManagerFactory" class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
		<property name="perstistenceUnitName" value="punit"/>
		<property name="dataSource" value="dataSource"/>
		<property name="jpaVendorAdapter">
			<bean class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter">
				<property name="showSql" value="true"></property>
			</bean>
		</property>
		
		<property name="jpaPropertyMap">
			<map>
				<entry key="hibernate.dialect" value="org.hibernate.dialect.MySQLDBDialect" />
				<entry key="hibernate.hbm2ddl.auto" value="true" />
				<entry key="hibernate.format_sql" value="true" />
			</map>				
		</property>
	</bean>

Add Transaction Manager and Properties

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

Add Data Source

	<bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource">
		<property name="driverClassName" value="com.mysql.cj.jdbc.Driver"/>
		<property name="url" value="jdbc:mysql://localhost:3306/fitnessTracker?autoReconnect=true"/>
		<property name="username" value="noreal" />
		<property name="password" value="noreal" />
	</bean>

Annotations

Generally three layers, controller, service and repository with a model

Model

Models have @Entity

 @Entity
 @Table(name="Exercises")

 public class Exercise {
	
	@Id
	@GeneratedValue
	@Column(name="EXERCIDE_ID")
	private Long id;

	public Long getId() {
		return id;
	}

	public void setId(Long id) {
		this.id = id;
	}
 }

Service

Service have @Service

 @Service("exerciseService")
 public class ExerciseServiceImpl implements ExerciseService {

	@Autowired
	private ExerciseRepository exerciseRepository; 
	
	public List<Activity> findAllActivities() {
		
		List<Activity> activities = new ArrayList<Activity>();
		
		Activity run = new Activity();
		run.setDesc("Run");
		activities.add(run);
		
		Activity bike = new Activity();
		bike.setDesc("Bike");
		activities.add(bike);
		
		Activity swim = new Activity();
		swim.setDesc("Swim");
		activities.add(swim);
		
		return activities;
	}

	@Transactional
	public Exercise save(Exercise exercise) {
		
		exercise = exerciseRepository.save(exercise);
		
		return exercise;
	}
 }

Repository

Repository have @Repository

 @Repository("exerciseRepository")
 public class ExerciseRepositoryImpl implements ExerciseRepository {

	@PersistenceContext
	private EntityManager em;
	
	public Exercise save(Exercise exercise) {
		
		em.persist(exercise);
		
		em.flush();
		
		return exercise;
	}
 }