JPA Dao Layer with default implementation by an abstract class. This is something similar to CrudRepository in spring data jpa

applicationContext.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
	xmlns:camel="http://camel.apache.org/schema/spring" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xmlns:context="http://www.springframework.org/schema/context"
	xmlns:tx="http://www.springframework.org/schema/tx"
	xsi:schemaLocation="http://camel.apache.org/schema/spring http://camel.apache.org/schema/spring/camel-spring.xsd
		http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
		http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-3.1.xsd
		http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.1.xsd">
	<context:annotation-config />
	<context:component-scan base-package="com.xyz" />
	<context:property-placeholder location="classpath:com/boohoo/esb/properties/database.properties" />
	<tx:annotation-driven transaction-manager="txManager" />
  
  <!-- 
  Enables interpretation of the @PersistenceUnit/@PersistenceContext 
  annotations providing convenient access to EntityManagerFactory/EntityManager 
  -->
	<bean class="org.springframework.orm.jpa.support.PersistenceAnnotationBeanPostProcessor" />

	<bean id="entityManagerFactory" class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
		<property name="persistenceUnitName" value="reportIncident" />
		<property name="jpaVendorAdapter" ref="jpaAdapterMYSQL" />
		<property name="dataSource" ref="dataSource" />
	</bean>


	<!-- OpenJPA MySQL adapter -->
	<bean id="jpaAdapterMYSQL" class="org.springframework.orm.jpa.vendor.OpenJpaVendorAdapter">
		<property name="databasePlatform" value="org.apache.openjpa.jdbc.sql.MySQLDictionary" />
		<property name="showSql" value="true" />
	</bean>


	<!-- DataSource MYSQL -->
	<bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource">
		<property name="driverClassName" value="${driver.class.name}" />
		<property name="url" value="${url}" />
		<property name="username" value="${username}" />
		<property name="password" value="${password}" />
	</bean>

	<!-- TransactionManager is required -->
	<bean id="txManager" class="org.springframework.orm.jpa.JpaTransactionManager">
		<property name="entityManagerFactory" ref="entityManagerFactory" />
		<property name="dataSource" ref="dataSource" />
	</bean>
  
</beans>

BaseDao.java

import java.io.Serializable;

public interface BaseDao<T, ID extends Serializable> {
  /**
	 * Saves a given entity. Use the returned instance for further operations as the save operation might have changed the
	 * entity instance completely.
	 * 
	 * @param entity
	 * @return the saved entity
	 */
	<S extends T> S save(S entity);

	/**
	 * Saves all given entities.
	 * 
	 * @param entities
	 * @return the saved entities
	 * @throws IllegalArgumentException in case the given entity is (@literal null}.
	 */
	<S extends T> Iterable<S> save(Iterable<S> entities);

	/**
	 * Retrieves an entity by its id.
	 * 
	 * @param id must not be {@literal null}.
	 * @return the entity with the given id or {@literal null} if none found
	 * @throws IllegalArgumentException if {@code id} is {@literal null}
	 */
	<S extends T> S findOne(ID id);

	/**
	 * Returns whether an entity with the given id exists.
	 * 
	 * @param id must not be {@literal null}.
	 * @return true if an entity with the given id exists, {@literal false} otherwise
	 * @throws IllegalArgumentException if {@code id} is {@literal null}
	 */
	boolean exists(ID id);

	/**
	 * Returns all instances of the type.
	 * 
	 * @return all entities
	 */
	Iterable<T> findAll();

	/**
	 * Returns all instances of the type with the given IDs.
	 * 
	 * @param ids
	 * @return
	 */
	Iterable<T> findAll(Iterable<ID> ids);

	/**
	 * Returns the number of entities available.
	 * 
	 * @return the number of entities
	 */
	long count();

	/**
	 * Deletes the entity with the given id.
	 * 
	 * @param id must not be {@literal null}.
	 * @throws IllegalArgumentException in case the given {@code id} is {@literal null}
	 */
	void delete(ID id);

	/**
	 * Deletes a given entity.
	 * 
	 * @param entity
	 * @throws IllegalArgumentException in case the given entity is (@literal null}.
	 */
	void delete(T entity);

	/**
	 * Deletes the given entities.
	 * 
	 * @param entities
	 * @throws IllegalArgumentException in case the given {@link Iterable} is (@literal null}.
	 */
	void delete(Iterable<? extends T> entities);

	/**
	 * Deletes all entities managed by the repository.
	 */
	void deleteAll();
}

gistfile1.txt

import static org.junit.Assert.*;

import org.apache.commons.lang.RandomStringUtils;
import org.junit.After;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.test.context.ContextConfiguration;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;

import com.xyz.model.StockDao;

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(locations="classpath:testApplicationContext.xml")
public class StockDaoImplTest {
	@Autowired
	StockDao stockDao;
	
	@Test
	public void save(){
		Stock s = new Stock();
		s.setQuantity(Integer.parseInt(RandomStringUtils.randomNumeric(4)));
		s.setSku(RandomStringUtils.randomAlphabetic(10));
		s.setUpdatedDateTime("2012-12-12");
		Stock save = stockDao.save(s);
		assertNotNull(save.getId());
	}
	
	@After
	public void tearDown(){
		stockDao.deleteAll();
	}
}

JpaBaseDao.java

import java.lang.reflect.ParameterizedType;
import java.util.ArrayList;
import java.util.List;

import javax.persistence.EntityManager;
import javax.persistence.PersistenceContext;
import javax.persistence.Query;

public abstract class JpaBaseDao<T, ID> implements BaseDao<T, Integer>{
  protected Class<T> entityClass;

	@PersistenceContext
	protected EntityManager entityManager;

	public JpaBaseDao() {
		ParameterizedType genericSuperclass = (ParameterizedType) getClass()
				.getGenericSuperclass();
		// extracting the entity class
		this.entityClass = (Class<T>) genericSuperclass.getActualTypeArguments()[0];
	}
	
	@Override
	public <S extends T> S save(S entity) {
		return entityManager.merge(entity);
	}
	
	@Override
	public long count() {
		Query query = entityManager.createQuery("select count(*) from " + entityClass.getName());
		return query.executeUpdate();
	}
	
	@Override
	public void delete(Integer id) {
		T findOne = findOne(id);
		if(findOne != null)
			delete(findOne);
		else{
			
		}
	}
	
	@Override
	public void delete(Iterable<? extends T> entities) {
		for (T t : entities) {
			if(t != null)
				delete(t);
		}
	}
	@Override
	public void delete(T entity) {
		entityManager.remove(entity);
	}
	
	@Override
	public void deleteAll() {
		Query query = entityManager.createQuery("DELETE FROM " + entityClass.getName() + " d");
		query.executeUpdate();
	}
	
	@Override
	public boolean exists(Integer id) {
		return findOne(id) == null ? false : true;
	}
	
	@Override
	public Iterable<T> findAll() {
		Query query = entityManager.createQuery("SELECT A FROM " + entityClass.getName() + " A");
		return (List<T>)query.getResultList();
	}
	
	@Override
	public Iterable<T> findAll(Iterable<Integer> ids) {
		List<T> list = new ArrayList<T>();
		for (Integer id : ids) {
			if(id != null)
				list.add(findOne(id));
			else{
				//TODO: Log it
			}
		}
		return list;
	}
	
	@Override
	public T findOne(Integer id) {
		return entityManager.find(entityClass, id);
	}
	
	@Override
	public <S extends T> Iterable<S> save(Iterable<S> entities) {
		List<S> list = new ArrayList<S>();
		for (S s : entities) {
			entityManager.merge(s);
		}
		return list;
	}
}

StockDao.java

import com.boohoo.esb.database.test.model.SageMasterStock;

public interface StockDao extends BaseDao<Stock, Integer> {
  public Integer updateStock(Stock stock);
}

StockDaoImpl.java

@Repository("stockDao")
@Transactional
public class StockDaoImpl extends JpaBaseDao<Stock, Integer> implements StockDao {
  
	public Integer updateSageStock(Stock stock) {
		// Implementation here
    return null;
	}
}