FAQ Hibernate interview questions & answers are covered below.
Q1. What is an Object-to-Relational Mapping (i.e. ORM) tool?
A1. There are several ways to persist data to a database from your Java applications.
1) Direct JDBC SQL statements for the CRUD (Create,
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Q. What is a first-level cache in Hibernate? A. First-level cache always is associated with a “Session” object. Hibernate uses this cache by default. You can’t turn it off. Hibernate caches the SQL statements like insert, update, delete, etc in the first-level cache. By default, … Read more ›...
Extends 15+ Hibernate interview questions & answers – Q1 – Q7. Hibernate interview questions & answers with diagrams & code snippets to not only prepare for the job interviews, but also to easily grasp the concepts Q9. Explain hibernate object states? Explain hibernate objects life cycle? … Read more ›...
This extends Spring Boot annotations interview Q&As and Java exception handling interview questions and answers. Q01. What is exception handling & why is it important? A01. In Java, Exceptions are objects that are thrown when an error or unexpected situation occurs during the execution of a program. … Read more...
This extends 15 Spring Boot interview questions & answers. Spring Boot & Spring Cloud are used for building Microservices architecture. Q1. What is Spring Cloud? A1. Spring Boot is widely used to develop MicroServices. As many organisations deploy these services on the cloud like AWS, … Read more ›...
Spring IO Platform is all about “list of dependencies and their versions that work well together”. It is implemented as a Maven POM file via Maven Bill-of-Materials dependency that you can import into your projects to set the versions for dependencies. You can go to “ … Read more ›...
conf/db.properties
# jdbc.X
jdbc.driverClassName=org.hsqldb.jdbcDriver
jdbc.url=jdbc:hsqldb:hsql://localhost/mytestdb
jdbc.user=SA
jdbc.pass=
# hibernate.X
hibernate.dialect=org.hibernate.dialect.HSQLDialect
hibernate.show_sql=false
hibernate.hbm2ddl.auto=
#1. Register a Properties File in Application Context XML
The “<property-placeholder>” tag.
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<context:property-placeholder location="classpath:conf/db.properties" /> |
OR
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<bean class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer"> <property name="locations"> <list> <value>classpath:conf/db.properties</value> </list> </property> <property name="ignoreUnresolvablePlaceholders" value="true"/> </bean> |
#2.
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This extedns configuring JDBC and JPA to configure the TransactionManager.
Example #1 Wiring JDBC Transaction Manager
Note: @EnableTransactionManagement annotation
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@Configuration @ImportResource("application.yml") @EnableTransactionManagement public class AppConfig @Bean public DriverManagerDataSource datasource() { DriverManagerDataSource ds = new DriverManagerDataSource(); ds.setDriverClassName(environment.getRequiredProperty("spring.datasource.driver-class-name")); ds.setUrl(environment.getRequiredProperty("spring.datasource.url")); ds.setUsername(environment.getRequiredProperty("spring.datasource.username")); ds.setPassword(environment.getRequiredProperty("spring.datasource.password")); return ds; } @Bean public JdbcTemplate jdbcTemplate() { return new JdbcTemplate(datasource()); } @Bean public DataSourceTransactionManager transactionManager() { final DataSourceTransactionManager transactionManager = new DataSourceTransactionManager(datasource()); return transactionManager; } } |
If you want to create a mock transaction manager, then you can do
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package sample; import org.springframework.stereotype.Service; import org.springframework.transaction.PlatformTransactionManager; import org.springframework.transaction.TransactionDefinition; import org.springframework.transaction.TransactionException; import org.springframework.transaction.TransactionStatus; public class MockedTransactionManager implements PlatformTransactionManager { @Override public TransactionStatus getTransaction(TransactionDefinition definition) throws TransactionException { return null; } @Override public void commit(TransactionStatus status) throws TransactionException { } @Override public void rollback(TransactionStatus status) throws TransactionException { } } |
Also,
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Example #1 Wiring JDBC Datasource
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@Configuration @ImportResource("application.yml") public class AppConfig { @Autowired private Environment environment; @Bean public DriverManagerDataSource datasource() { DriverManagerDataSource ds = new DriverManagerDataSource(); ds.setDriverClassName(environment.getRequiredProperty("spring.datasource.driver-class-name")); ds.setUrl(environment.getRequiredProperty("spring.datasource.url")); ds.setUsername(environment.getRequiredProperty("spring.datasource.username")); ds.setPassword(environment.getRequiredProperty("spring.datasource.password")); return ds; } } |
application.yml where the datasource properties are read.
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############ # Datasource properties ############ spring: datasource: driver-class-name: com.sybase.jdbc4.jdbc.SybDataSource url: jdbc:sybase:Tds:mydbhost:5700/my_db username: user password: pwd |
Example #2 Wiring JDBC Datasource with JNDI
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@Configuration @ImportResource("application.yml") public class AppConfig { @Autowired private Environment environment; @Bean public DataSource dataSource() { final JndiDataSourceLookup jndiLookup = new JndiDataSourceLookup(); final String dataSourceJndi = environment.getRequiredProperty("spring.datasource.jndi"); return jndiLookup.getDataSource(dataSourceJndi); } } |
Example #3 Wiring JDBC Embedded Datasource for integration testing
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@Configuration @ImportResource("application.yml") public class AppConfig { @Autowired private Environment environment; @Bean public DataSource dataSource() { final EmbeddedDatabaseBuilder builder = new EmbeddedDatabaseBuilder(); builder.setType(EmbeddedDatabaseType.HSQL); builder.addScript("classpath:hsqldb-oracle.sql"); builder.addDefaultScripts(); // defaults are schema.sql and data.sql return builder.build(); } } |
Example #4 Wiring up the JdbcTemplate by passing in the datasource
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@Configuration @ImportResource("application.yml") public class AppConfig { @Autowired private Environment environment; @Bean public JdbcTemplate jdbcTemplate() { return new JdbcTemplate(datasource()); } @Bean public DataSource dataSource() { //...... } } |
Example #5 Wiring up a DAO...
Step 1: Define the messaging system connectivity, destination (e.g. topic or queue) and message selector properties via a YAML or .properties file. Here is an example of application.yml file.
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############################# # MQ Settings # ############################# spring: mq: hostname: my-mq-host channel: mychannel port: 2500 queue.manager: GHTFDS environment: EN7 # MQ SSL settings -- uncomment the below section to enable SSL for MQ # ssl: # enabled: # cipher.suite: # keyStore: # keyStorePassword: # MQ misc settings, if not set, will set with sensible defaults # transport.type: 1 # client.id: YOUR_CLIENT_NAME # delivery.mode: 2 ############################################### # topic selector # ############################################### myapp: app: title: my app systemname: send-prices PriceSubscriptionName: price_event selector: PriceEventTopic: TOPIC/PRICE PriceEventMessageType: event PriceEventOriginator: PRICE PriceEventCategory: business/price |
Step 2: MQTopicConnectionFactory The Java based Spring configuration defining the connection factory. … Read more ›...