Develop Reference

Is there a way to map mutliple databases with same table names in a dynamic way?

First time I encounter this problem. The situation is:
I have more than 100 SQL databases, each one correspond to a different company and each one have the same three tables (same table names, same column names, same column data type).
Is there some way to map all these databases dynamically?
With dynamically I mean to have one class to which I can refer and make any CRUD operation.

After some research I could see what I wanted to do:
Basically I needed to change my data source in run time, for that I used a spring framework interface called AbstracRoutingDataSource.
Example:
Implementing AbstractRoutingDataSource:
public class MultiRoutingDataSource extends AbstractRoutingDataSource {
#Override
protected Object determineCurrentLookupKey() {
return DBContextHolder.getCurrentDb();
}
}
DatabaseContextHolder:
public class DBContextHolder {
private static final ThreadLocal<DBTypeEnum> contextHolder = new ThreadLocal<>();
public static void setCurrentDb(DBTypeEnum dbType) {
contextHolder.set(dbType);
}
public static DBTypeEnum getCurrentDb() {
return contextHolder.get();
}
public static void clear() {
contextHolder.remove();
}
}
Database type enum:
public enum DBTypeEnum{
DATASOURCE1("DATASOURCE1"),
DATASOURCE2("DATASOURCE2");
DBTypeEnum(final String dbTypeEnum){
this.dbTypeEnum = dbTypeEnum;
}
private String dbTypeEnum;
public String dbTypeEnum(){
return dbTypeEnum;
}
}
Persistence configuration:
#Configuration
#EnableTransactionManagement
#EnableJpaRepositories(
basePackages = "base.packages.path",
entityManagerFactoryRef = "multiEntityManager",
transactionManagerRef = "multiTransactionManager"
)
public class PersistenceConfiguration {
private final String PACKAGE_SCAN = "base.package.path";
#Bean(name = "dataSource1")
#ConfigurationProperties("spring.datasource1")
public DataSource dataSource1() {
return DataSourceBuilder.create().build();
}
#Bean(name = "dataSource2")
#ConfigurationProperties("spring.datasource2")
public DataSource dataSource2() {
return DataSourceBuilder.create().build();
}
#Bean(name = "multiRoutingDataSource")
public DataSource multiRoutingDataSource() {
Map<Object, Object> targetDataSources = new HashMap<>();
targetDataSources.put(DBTypeEnum.DATASOURCE1, dataSource1());
targetDataSources.put(DBTypeEnum.DATASOURCE2, dataSource2());
MultiRoutingDataSource multiRoutingDataSource = new MultiRoutingDataSource();
multiRoutingDataSource.setDefaultTargetDataSource(dataSource1());
multiRoutingDataSource.setTargetDataSources(targetDataSources);
return multiRoutingDataSource;
}
#Bean(name = "multiEntityManager")
public LocalContainerEntityManagerFactoryBean multiEntityManager() {
LocalContainerEntityManagerFactoryBean em = new LocalContainerEntityManagerFactoryBean();
em.setDataSource(multiRoutingDataSource());
em.setPackagesToScan(PACKAGE_SCAN);
HibernateJpaVendorAdapter vendorAdapter = new HibernateJpaVendorAdapter();
em.setJpaVendorAdapter(vendorAdapter);
em.setJpaProperties(hibernateProperties());
return em;
}
#Bean(name = "multiTransactionManager")
public PlatformTransactionManager multiTransactionManager() {
JpaTransactionManager transactionManager
= new JpaTransactionManager();
transactionManager.setEntityManagerFactory(
multiEntityManager().getObject());
return transactionManager;
}
#Bean(name = "dbSessionFactory")
public LocalSessionFactoryBean dbSessionFactory() {
LocalSessionFactoryBean sessionFactoryBean = new LocalSessionFactoryBean();
sessionFactoryBean.setDataSource(multiRoutingDataSource());
sessionFactoryBean.setPackagesToScan(PACKAGE_SCAN);
sessionFactoryBean.setHibernateProperties(hibernateProperties());
return sessionFactoryBean;
}
private Properties hibernateProperties() {
Properties properties = new Properties();
properties.put("hibernate.show_sql", true);
properties.put("hibernate.format_sql", true);
return properties;
}
}
Then you need to have all of your database information in a .properties file:
spring.datasource1.jdbcUrl=jdbc:sql:sql-url:3306/datasource1
spring.datasource1.username=username
spring.datasource1.password=password
spring.datasource1.driver-class-name= Driver
spring.datasource2.jdbcUrl=jdbc:sql:sql-url:3306/datasource2
spring.datasource2.username=username
spring.datasource2.password=password
spring.datasource2.driver-class-name= Driver
Then you need to map your entity:
#Entity
#Table(name = "table_name")
#Getter
#Setter
public class MyEntity implements Serializable {
#Id
#Column(name = "ID", columnDefinition = "varchar(17)")
private String id;
//more fields...
}
I used spring CrudRepositories interface for this entity
public interface IMyEntityRepository extends CrudRepository<MyEntity, String> {
}
Finally my controller is prepared to change datasource depending on a JSON field in my request.
JSON:
{
"dataSource":"DATASOURCE1"
//more fields ...
}
RESTController:
#PutMapping("/url/{id}")
public ResponseEntity<?> editMyEntity(#RequestBody RequestObject request #PathVariable String id){
DBContextHolder.setCurrentDb(DBTypeEnum.valueOf(request.getDataSource);
iMyEntitiRepository.getMyEntity(id);
//...
}

sharding using jpa repository dynamically

I have 3 shards(3 different Ips, usernames and passwords). I am using spring boot, spring jpa to save the data in DB. Let's say Customer is my entity. Let's assume, based on some organizationId, I need to insert/update/select the data from different databases.
Current approach :
#Getter
#Setter
#Entity
#Table
#NoArgsConstructor
public class Customer {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
private Long customerId;
private String firstName;
private String lastName;
private Long organizationId;
}
package lane1;
#Repository
public interface CustomerRepo1 extends CrudRepository<Customer,Long> {
}
package lane2;
#Repository
public interface CustomerRepo2 extends CrudRepository<Customer,Long> {
}
package lane3;
#Repository
public interface CustomerRepo3 extends CrudRepository<Customer,Long> {
}
I am creating 3 datasources(DatasourceLane1, DatasourceLane2, DatasourceLane3) and setting the base packages in the configuration class.
#Configuration
#ConfigurationProperties("DatasourceLane1")
#EnableJpaRepositories(basePackages = "lane1", entityManagerFactoryRef = "lane1EntityManagerFactory",
transactionManagerRef = "lane1TransactionManager")
public class DBConfigurationLane1 {
#NotNull
private String username;
#NotNull
private String password;
#NotNull
private String url;
public void setUsername(String username) {
this.username = username;
}
public void setPassword(String password) {
this.password = password;
}
public void setUrl(String url) {
this.url = url;
}
//#Primary
#Bean
DataSource dataSourceLane1() throws SQLException {
HikariDataSource dataSource = new HikariDataSource();
dataSource.setUsername(username);
dataSource.setPassword(password);
dataSource.setJdbcUrl(url);
return dataSource;
}
//#Primary
#Bean(name = "lane1EntityManagerFactory")
public EntityManagerFactory propEntityManagerFactory() throws SQLException {
Properties properties = new Properties();
// properties.put("hibernate.hbm2ddl.auto", "update");
LocalContainerEntityManagerFactoryBean em = new LocalContainerEntityManagerFactoryBean();
em.setPersistenceUnitName("lane1");
em.setDataSource(dataSourceLane1());
em.setJpaVendorAdapter(new HibernateJpaVendorAdapter());
em.setPackagesToScan("lane1");
em.setJpaProperties(properties);
em.afterPropertiesSet();
return em.getObject();
}
//#Primary
#Bean(name = "lane1TransactionManager")
public PlatformTransactionManager propTransactionManager(
#Qualifier("lane1EntityManagerFactory") EntityManagerFactory barEntityManagerFactory) {
return new JpaTransactionManager(barEntityManagerFactory);
}
}
Similarly I have datasource2 and datasource3.
My goal is to have single repository class and dynamically use different datasource based on organizationId.
NOTE : I want to reuse all SimpleJpaRepository(CrudRepository) methods too.
It would be great if someone helps me with code examples. Thank you in advance.

Getting org.hibernate.MappingException: Unknown entity. Using Spring framework

I have just started working in java spring framework. Am just trying to populate a simple table with columns id and a name. But am getting :
Unknown entity: org.hibernate.MappingException
I get that it is commonly encountered exception. But I couldn't fix this. You can find the The entity, dao and hibernate config am using below.
HibernateConfig.java
#Getter #Setter
#Configuration#ConfigurationProperties(prefix = "databaseConfiguration")
public class HibernateConfig {
#Value("${driverClass}")
private String driverClass;
#Value("${url}")
private String url;
#Value("username")
private String username;
#Value("password")
private String password;
#Value("${hibernateDialect}")
private String hibernateDialect;
#Value("${hbm2ddlAuto}")
private String hbm2ddlAuto;
private Integer minSize;
private Integer maxSize;
#Bean
public DataSource dataSource() {
DriverManagerDataSource dataSource = new DriverManagerDataSource();
dataSource.setDriverClassName(driverClass);
dataSource.setUrl(url);
dataSource.setUsername(username);
dataSource.setPassword(password);
return dataSource;
}
#Bean
public Properties hibernateProperties() {
Properties properties = new Properties();
properties.put("hibernate.hbm2ddl.auto", hbm2ddlAuto);
properties.put("hibernate.dialect", hibernateDialect);
properties.put("hibernate.c3p0.min_size", minSize);
properties.put("hibernate.c3p0.max_size", maxSize);
return properties;
}
#Bean
public LocalSessionFactoryBean sessionFactory(DataSource dataSource) {
LocalSessionFactoryBean sessionFactory = new LocalSessionFactoryBean();
sessionFactory.setDataSource(dataSource);
sessionFactory.setHibernateProperties(hibernateProperties());
return sessionFactory;
}
#Bean
public ITestDao testDao() {
ITestDao testDao = new TestDao();
return testDao;
}
}
All the properties are being taken from the .yml file. ITestDao is the interface with abstract add() method in it.
Entity class
#Getter
#Setter
#Entity
#Table(name = "test")
public class Test {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "id", nullable = false, unique = true)
private Long id;
#Column(name = "dump", nullable = false)
private String dump;
}
Dao class
#Repository
#Transactional
#Getter
#Setter
public class TestDao implements ITestDao {
#Autowired
private LocalSessionFactoryBean sessionFactoryBean;
public Test add(Test test) {
try {
sessionFactoryBean.getObject().getCurrentSession().getTransaction().begin();
sessionFactoryBean.getObject().getCurrentSession().persist(test);
} finally {
sessionFactoryBean.getObject().getCurrentSession().getTransaction().commit();
}
return test;
}
}
A service method will call this dao with #Transactional annotated above it. But while calling this add() dao method am getting Unknown entity:
org.hibernate.MappingException

Try this way :
#Bean
public LocalSessionFactoryBean sessionFactory(DataSource dataSource) {
LocalSessionFactoryBean sessionFactory = new LocalSessionFactoryBean();
sessionFactory.setDataSource(dataSource);
sessionFactory.setPackagesToScan(new String[] { "my.package.model" });// You need to provide to adapt : my.package.model
sessionFactory.setHibernateProperties(hibernateProperties());
return sessionFactory;
}
Good luck

You might be missing below annotation.
#EntityScan("some.known.persistence")
The #EntityScan only identifies which classes should be used by a specific persistence context.

#Autowired SessionFactory returning null spring in Java configuration

I m having null pointer exception in sessionFactory when i try to use DI in sessionFactory I have to turn spring 3 project into Spring 4 with no xml. I dont know what the problem i m facing, SessionFactory doesnot autowired at all. when i try to test case generic doa Add Method
here is my Configuration File for bean
#Configuration
#EnableTransactionManagement
#EnableWebMvc
#ComponentScan(basePackages = "io.github.bibekshakya35.ehealth")
public class EhealthCofiguration {
#Bean
public ViewResolver getViewResolver() {
InternalResourceViewResolver viewResolver = new InternalResourceViewResolver();
viewResolver.setViewClass(JstlView.class);
viewResolver.setPrefix("/WEB-INF/view/");
viewResolver.setSuffix(".jsp");
return viewResolver;
}
#Bean(name = "dataSource")
public javax.sql.DataSource getDataSource() {
BasicDataSource dataSource = new BasicDataSource();
dataSource.setDriverClassName("org.postgresql.Driver");
dataSource.setUrl("jdbc:postgresql://localhost:5432/ehealth");
dataSource.setUsername("test");
dataSource.setPassword("test123");
return dataSource;
}
#Autowired
#Bean(name = "sessionFactory")
public SessionFactory getSessionFactory(javax.sql.DataSource dataSource) {
LocalSessionFactoryBuilder sessionBuilder = new LocalSessionFactoryBuilder(dataSource);
sessionBuilder.scanPackages("io.github.bibekshakya35.ehealth.model");
sessionBuilder.addProperties(getHibernateProperties());
return sessionBuilder.buildSessionFactory();
}
private Properties getHibernateProperties() {
Properties properties = new Properties();
properties.put("hibernate.show_sql", "true");
properties.put("hibernate.dialect", "org.hibernate.dialect.PostgreSQLDialect");
properties.put("hibernate.hbm2ddl.auto", "update");
return properties;
}
#Autowired
#Bean(name = "transactionManager")
public HibernateTransactionManager getTransactionManager(
SessionFactory sessionFactory) {
HibernateTransactionManager transactionManager = new HibernateTransactionManager(
sessionFactory);
return transactionManager;
}
}
to load this class i have created
public class EhealthWebAppIntializer implements WebApplicationInitializer {
#Override
public void onStartup(ServletContext servletContext) throws ServletException {
AnnotationConfigWebApplicationContext applicationContext = new AnnotationConfigWebApplicationContext();
applicationContext.register(EhealthCofiguration.class);
ServletRegistration.Dynamic dispatcher =servletContext.addServlet("SpringDispatcher", new DispatcherServlet(applicationContext));
dispatcher.setLoadOnStartup(1);
dispatcher.addMapping("/");
}
}
this is my generic doa class where i m injecting SessionFactory when it try to access sessionFactory.getCurrentSession(); NPE is occur,
#Repository
#Transactional
public class HibernateDAO<T extends Serializable> implements IGenericDao<T> {
private Class<T> clazz;
Session session;
#Autowired
SessionFactory sessionFactory;
private static final Logger LOG = Logger.getLogger(HibernateDAO.class.getName());
#Override
public void setClazz(Class<T> clazzToSet) {
this.clazz = clazzToSet;
}
#Override
public void create(T entity) {
session = getCurrentSession();
LOG.log(Level.INFO, "inside create entity and you just bind your session to the current one{0}", session.toString());
session.saveOrUpdate(entity);
LOG.info("saved");
session.flush();
session.refresh(entity);
}
protected Session getCurrentSession() {
return sessionFactory.getCurrentSession();
}
}
Here is my stack trace for NPE
Exception in thread "main" java.lang.NullPointerException
at io.github.bibekshakya35.ehealth.DAO.genericdao.HibernateDAO.getCurrentSession(HibernateDAO.java:115)
at io.github.bibekshakya35.ehealth.DAO.genericdao.HibernateDAO.create(HibernateDAO.java:85)
at io.github.bibekshakya35.ehealth.service.impl.user.main(user.java:46)
here is my user entity
#Entity
#Table(name = "users")
public class User implements Serializable, AbstractEntity {
#Id
#Column(name = "username",unique = true)
private String userName;
#NotNull(message = "password cannot be empty")
#Column(name = "users_password")
private String userPassword;
#Embedded
private UserProfile userProfile;
#Embedded
private AuditInfo auditInfo;
#Enumerated(EnumType.STRING)
private UserType userType;
#Column(name = "is_active")
private boolean active = true;
//getter n setter
}

In chat, You provided me with this code :
public static void main(String[] args) {
User user = new User();
IGenericDao<User> iGenericDao = new HibernateDAO<>();
user.setUserName("bibekshakya35");
user.setUserPassword("ros3");
user.setUserType(UserType.GUEST);
user.setActive(true);
UserProfile userProfile = new UserProfile();
userProfile.setAge(21);
userProfile.setBasicInfo("kdhsa");
userProfile.setEmailId("dsadas#gmail.com");
userProfile.setUserGender(UserGender.Male);
userProfile.setFullname("bibek shakya");
userProfile.setMobileNumber("45454545");
userProfile.setLandLineNumber("445444");
userProfile.setUserProfilePic("index.jsp");
user.setUserProfile(userProfile);
AuditInfo auditInfo = new AuditInfo();
auditInfo.setCreatedOn(new Date());
auditInfo.setModifiedOn(new Date());
auditInfo.setVerifiedOn(new Date());
user.setAuditInfo(auditInfo);
iGenericDao.create(user);
}
Cause of error:
As You are creating the new HibernateDAO instance like this IGenericDao<User> iGenericDao = new HibernateDAO<>(); This is creating the problem.
In the case where You are using annotations, creating new instance manually ,usually causes the above mentioned error.
Reason of error:
Spring can only autowire beans that it manages; if you call new to create a bean yourself, #Autowired fields don't get filled in (and methods like #PostConstruct aren't called).
Solution:
You need to add #autowired to the HibernateDAO which will instantiate it with the exact class which includes the real #Autowired SessionFactory.
Example:
Usually we do it in the class which is itself annotated with annotations like #Controller or #Service.
Like this
#Controller
#RequestMapping(value="/someURL")
public class mainClass {
#Autowired
HibernateDAO abc;
//Code (methods) to test Your CRUD Operations
}

No transactional EntityManager available when Persisting an object

I have got No transactional EntityManager available exception when I tried to persist an object.
I have a Spring project with the following configuration class:
#Configuration
#ComponentScan
#EnableTransactionManagement
#EnableJpaRepositories
public class SpringConfiguration {
#Bean(name = "entityManagerFactory")
public LocalContainerEntityManagerFactoryBean emf(DataSource dataSource) {
LocalContainerEntityManagerFactoryBean emf =new LocalContainerEntityManagerFactoryBean();
emf.setDataSource(dataSource);
Properties jpaProperties = new Properties();
jpaProperties.put("hibernate.hbm2ddl.auto", "create-drop");
jpaProperties.put("hibernate.show_sql", "true");
emf.setJpaProperties(jpaProperties);
emf.setPackagesToScan(
new String[] {"ds.core.entity"});
emf.setJpaVendorAdapter(
new HibernateJpaVendorAdapter());
return emf;
}
#Bean(name = "transactionManager")
public PlatformTransactionManager transactionManager(EntityManagerFactory emf,DataSource dataSource) {
JpaTransactionManager tm =
new JpaTransactionManager();
tm.setEntityManagerFactory(emf);
tm.setDataSource(dataSource);
return tm;
}
And an entity class:
#Entity
public class Type {
#Id #GeneratedValue
private Long id;
private String name;
}
and Jpa implementation class :
#Repository
public class JpaTypeRepo implements TypeRepo {
#PersistenceContext
private EntityManager em;
#Override
public Type insertRecord(Type data) {
em.persist(data);
return data;
}
}
And finally a Service Class with Init():
#Transactional
#Service
public class InitDbService {
#Autowired
private TypeRepo typeRepo;
#PostConstruct
public void init() {
Type type=new Type();
type.setName("newName");
typeRepo.insertRecord(type);
}}

just add #Transactional annotation to the class :JpaTypeRepo
as following:
#Transactional
#Repository
public class JpaTypeRepo implements TypeRepo {
#PersistenceContext
private EntityManager em;
#Override
public Type insertRecord(Type data) {
em.persist(data);
return data;
}
}