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What-is-Hibernate

Introduction to Hibernate

Officially known as Hibernate ORM, it is an object-relational mapping tool or framework for the Java programming language. It is a free software under GNU Lesser General Public License 2.1. It aims to provide the user with the framework for object-relational impedance mapping and manages persistent database accesses with very high-level object handling functions.

Architecture

To learn more about it, we need to understand its architecture which comprises of :

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  • A Java application code consists of all the classes, variables, and objects that define the application’s business logic. These classes communicate with the Hibernate.
  • Then comes the Hibernate and its core principles, using which we could persist ( store or save and retrieve ) the objects of our business layer classes by communicating with the database server layer.
  • It uses the Java core API, Java Database Connectivity(JDBC), Java Transaction API(JTA), Java Naming and Directory Interface(JNDI) to communicate with the database to persist the state of an object by performing read, create, update, delete(CRUD) operations.

It is used to communicate with the database. Here we just create some entities, which are nothing but a java class that will create a database table for us in the database.

Framework

Here we come across a question of why we use hibernate framework of java if we already have the core java principles. So here is the answer to that :

  • Used best JDBC concepts such as:
  1. Rowset instead of ResultSet
  2. DataSource (connection pooling) instead of DriverManager
  3. Batch operations instead of individual operation
  4. PreparedStatement instead of Statement
  • Project development cost is reduced to a large factor.
  • No memory leaks
  • Managing associations such as one-to-many, etc., is simpler and easier than working with collection properties like java.util.Set, List, Map.
  • Being an ORM framework, it will get all its advantages:
  • Supports Second level cache
  • The object becomes a record and vice versa.
  • Additionally supports Object Query Language (HQL)
  • Supports multiple primary key generators

Features

So it was all about the java hibernate framework and its architecture; let’s talk about the features of the latest hibernate stable released 57 days ago, i.e., 23 Feb 2019. Developed by Red Hat software, it is a virtual machine platform with lots of features :

  • It supports JMX and JCA.
  • It provides a feature of J2EE integration.
  • At system initialization time, it generates SQL.
  • Optionally provide internal connection pooling and prepared statement caching.
  • It supports optimistic locking with versioning.
  • It provides outer join fetching.
  • It introduces Lazy initialization.
  • It provides a session-level cache and optional second-level cache.
  • It provides Dual-layer Cache Architecture.
  • Automatic generation of the primary key.
  • It supports the tough concept of composite keys.
  • It supports the Detached object concept.
  • It introduces the automatic Dirty Checking concept.
  • It provides transparent persistence without byte code processing.
  • It provides Object/Relational mappings. Here are different O/R mapping strategies as multiple-objects to single-row mapping,
  • Polymorphic associations, bi-directional association, association filtering. It also provides XML mapping documents.
  • It provides different object-oriented query languages.
  • Minimal object-oriented Hibernate query language(HQL), native SQL queries
  • High object-oriented concept of criteria.

Why do we use Hibernate?

Here it was all the latest features of hibernate. Next comes the issue of why we use it, so here are the reasons why we prefer to use hibernate:

  • Transaction management
  • Associations
  • Inheritance
  • Hibernate caching
  • Versioning
  • Audit functionality
  • JPA annotation support
  • Connection Pooling
  • Avoiding try-catch blocks
  • Avoid lazy loading
  • Reduces repeat code

Advantages and Disadvantages of Hibernate

Briefing everything about hibernate, now it’s time to discuss the main agenda, the advantages, and the disadvantages of using hibernate.

Advantages

Covering the topic, let us start with the advantages of hibernate, which are as follows :

ORM – maintenance is easy and cost-effective.

  1. Transparent Persistence
  2. Database independent
  3. HQL – HQL’s advanced features like pagination and dynamic profiling are not present in SQL. So we can use it in hibernate.
  4. Dual-layer Caching
  5. Version Property
  6. Open Source and free software
  7. Scalability is easy
  8. Lazy-Loading – The lazy-loading concept fetches only the necessary object required for an application’s execution.
  9. Easy to Learn
  10. It also supports collections like List, Set, and Map.
  11. capability to generate primary keys
  12. It provides Dialect classes
  13. It supports relationships like One-To-Many, One-To-One, Many-To-Many-to-Many, and Many-To-One.

Disadvantages

With the advantages, it also has very fewer disadvantages. So here are the disadvantages of hibernate:

  1. little slower than pure JDBC
  2. boilerplate code issue
  3. generate many SQL statements in run time
  4. It is not suitable for Batch processing
  5. It is slow because it uses run-time reflection
  6. Lots of APIs to learn
  7. Sometimes debugging and performance tuning becomes difficult.
  8. Not suitable for small projects
  9. It does not allow multiple inserts
  10. Generates complex quires with many joins
  11. HQL queries cannot call PL/SQL program

Conclusion

So with all these topics covered, we also need to know about the future of hibernate. We can say that it will still be the dominant ORM tool for much longer, given that JPA is catching up rapidly. My impression is that it is the most broadly used implementation of JPA (before OpenJPA and EclipseLink) and that it’s native or core API is still more potent than JPA 2. For those reasons alone, I think it will be around for a long time. It is preferable to use Spring MVC in hibernate as it is the most compatible MVC. Using a persistence framework like Hibernate allows developers to focus on writing business logic code instead of writing an accurate and good persistence layer, including the SQL Queries, JDBC Code, connection management, etc. So I can suggest using hibernate as the java framework as it is the most prominent java framework used nowadays.

Recommended Articles

This is a guide to What is Hibernate. Here we have discussed the Architecture, Features, Framework, Advantages, and  Disadvantages of Hibernate. You may also have a look at the following articles to learn more –

  1. Hibernate Versions
  2. Hibernate Named Query
  3. Caching in Hibernate
  4. Hibernate Generator
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