Introduction to Hibernate
Officially known as Hibernate ORM, it is an object-relational mapping tool or framework for the Java programming language. It is the free software under GNU Lesser General Public License 2.1. It aims to provide the user with the framework to handle object-relational impedance mapping. It also manages persistent database accesses with very high-level object handling functions. It is a middleware framework of java used for object-relational mapping and for performing efficient object persistence.
To learn more about hibernate we need to understand its architecture which comprises of :
- A Java application code consists of all the classes, variables and objects that define the business logic of the application. 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 in order to persist the state of an object by performing read, create, update, delete(CRUD) operations.
It is basically used to communicate with the database. Here we just create some entities, which is nothing but a java class that will create a database table for us in the database.
Here we come across a question that 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:
- Rowset instead of ResultSet
- DataSource (connection pooling) instead of DriverManager
- Batch operations instead of individual operation
- PreparedStatement instead of Statement
- Project development cost is reduced to a large factor.
- No memory leaks
- Managing associations such as one-to-many, etc are simple and easy as compared to working with collection properties like java.util.Set, List, Map.
- Being an ORM framework, the Hibernate 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 of Hibernate
So it was all about 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 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 Detached object concept.
- It introduces 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 we use Hibernate?
Here it was all the latest features of hibernate. Next comes the issue that why we use it, so here are the reasons why we prefer to use hibernate:
- Transaction management
- Hibernate caching
- 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 that is the advantages and the disadvantages of using hibernate.
Covering the topic let us start with the advantages of hibernate which are as follows :
- ORM – maintenance is easy and cost-effective.
- Transparent Persistence
- Database independent
- HQL – HQL’s advanced features like pagination and dynamic profiling are not present in SQL. So we can use it in hibernate.
- Dual-layer Caching
- Version Property
- Open Source and free software
- Scalability is easy
- Lazy-Loading – The lazy-loading concept fetches only the necessary object that is required for the execution of an application.
- Easy to Learn
- Also supports collections like List, Set, Map.
- capability to generate primary keys
- Hibernate provided Dialect classes
- It supports relationships like One-To-Many, One-To-One, Many-To-Many-to-Many, Many-To-One
With the advantages, hibernate also has very fewer disadvantages. So here are the disadvantages of hibernate:
- little slower than pure JDBC
- boilerplate code issue
- generate many SQL statements in run time
- Hibernate is not suitable for Batch processing
- Hibernate is slow because it uses run time reflection
- Lots of API to learn
- Sometimes debugging and performance tuning becomes difficult.
- Not suitable for Small projects
- Does not allow multiple inserts
- Generates complex quires with many joins
- HQL queries cannot call PL/SQL program
So with all these topic covered we also need to know about the future of hibernate. We can say that Hibernate will still be the dominant ORM tool for much longer given that JPA is catching up rapidly. My impression is that Hibernate is the most broadly used implementation of JPA (before OpenJPA and EclipseLink), and also that it’s native or core API is still more powerful than JPA 2. For those reasons alone I think it will be around for a good long time. It is very preferable to use Spring MVC in hibernate as it is 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 which include writing 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.
This has been a guide to What is Hibernate. Here we discuss the Architecture, Features, Framework, Advantages, and Disadvantages of Hibernate. You may also have a look at the following articles to learn more –