What is a Session? Can you share a session object between different threads?

Session is a light weight and a non-threadsafe object (No, you cannot share it between threads) that represents a single unit-of-work with the database. Sessions are opened by a SessionFactory and then are closed when all work is complete. Session is the primary interface for the persistence service. A session obtains a database connection lazily (i.e. only when required). To avoid creating too many sessions ThreadLocal class can be used as shown below to get the current session no matter how many times you make call to the currentSession() method.
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public class HibernateUtil {
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public static final ThreadLocal local = new ThreadLocal();
public static Session currentSession() throws HibernateException 

{
Session session = (Session) local.get();
//open a new session if this thread has no session
if(session == null) 

{
session = sessionFactory.openSession();
local.set(session);
}
return session;
}
}
It is also vital that you close your session after your unit of work completes. Note: Keep your Hibernate Session API handy.

What is a SessionFactory? Is it a thread-safe object? | Java Hibernet

 SessionFactory is Hibernates concept of a single datastore and is threadsafe so that many threads can access it concurrently and request for sessions and immutable cache of compiled mappings for a single database. A SessionFactory is usually only built once at startup. SessionFactory should be wrapped in some kind of singleton so that it can be easily accessed in an application code.
 SessionFactory sessionFactory = new Configuration().configure().buildSessionfactory(); 

How will you configure Hibernate? | Java Hibernet

The configuration files hibernate.cfg.xml (or hibernate.properties) and mapping files *.hbm.xml are used by the Configuration class to create (i.e. configure and bootstrap hibernate) the SessionFactory, which in turn creates the Session instances. Session instances are the primary interface for the persistence service.

" hibernate.cfg.xml" (alternatively can use hibernate.properties): These two files are used to configure the hibernate sevice (connection driver class, connection URL, connection username, connection password, dialect etc). If both files are present in the classpath then hibernate.cfg.xml file overrides the settings found in the hibernate.properties file.

" Mapping files" (*.hbm.xml): These files are used to map persistent objects to a relational database. It is the best practice to store each object in an individual mapping file (i.e mapping file per class) because storing large number of persistent classes into one mapping file can be difficult to manage and maintain. The naming convention is to use the same name as the persistent (POJO) class name. For example Account.class will have a mapping file named Account.hbm.xml. Alternatively hibernate annotations can be used as part of your persistent class code instead of the *.hbm.xml files.

Explain the difference between hibernate and Spring? Java Hibernate

Hibernate is an ORM tool for data persistency. Spring is a framework for enterprise applications. Spring supports hibernate and provides the different classes which are templates that contains the common code.

Explain the main difference between Entity Beans and Hibernate? | Java Hibernet

Entity beans are to be implemented by containers, classes, descriptors. Hibernate is just a tool that quickly persist the object tree to a class hierarchy in a database and without using a single SQL statement. The inheritance and polymorphism is quite simply implemented in hibernate which is out of the box of EJB and a big drawback.

Why hibernate is advantageous over Entity Beans & JDBC?

An entity bean always works under the EJB container, which allows reusing of the object external to the container. An object can not be detached in entity beans and in hibernate detached objects are supported.
Hibernate is not database dependent where as JDBC is database dependent. Query tuning is not needed for hibernate as JDBC is needed. Data can be placed in multiple cache which is supported by hibernate, whereas in JDBC the cache is to be implemented.

What is the advantage of Hibernate over jdbc? | Java JDBC

The advantages of Hibernate over JDBC are:
•    Hibernate code will work well for all databases, for ex: Oracle,MySQL, etc. where as JDBC is database specific.
•    No knowledge of SQL is needed because Hibernate is a set of objects and a table is treated as an object, where as to work with JDBC, one need to know SQL.
•    Query tuning is not required in Hibernate. The query tuning is automatic in hibernate by using criteria queries, and the result of performance is at its best. Where as in JDBC the query tuning is to be done by the database authors.
•    With the support of cache of hibernate, the data can be placed in the cache for better performance. Where as in JDBC the java cache is to be implemented.