Hibernate means5/15/2023 How to configure hibernate?įirst, we need to install hibernate in our project. You will get to know more about HQL in the implementation.Ĭriteria object - It is used to execute object-oriented queries to retrieve objects from the database. We can write a query in SQL or use Hibernate Query Language (HQL). Query object - Query object is used to write queries to perform CRUD operations in the database. It is an optional object but should be used to ensure data integrity and if any error occurs rollback can be performed. Transaction object - It represents a unit of work with the database. It is not a thread-safe object therefore should be destroyed after the interaction is complete. Persistent objects are saved and retrieved through a session object. Session object - A session object is a lightweight object and created every time you need to interact with the database. The session factory is responsible for configuring hibernate with the configuration properties supplied by the configuration object. You need one session factory object per database. So, this object should be instantiated only once in our application and kept for later use. Session Factory object - A session factory is a heavy-weight thread safe object and used by multiple threads at a time. It represents the configuration and mapping properties required by the hibernate. It checks whether the configuration file is syntactically correct or not. The configuration object is the parent object from which all the other objects are created. The configuration object is created only once during application initialization. You create these objects manually whenever needed.Ĭonfiguration object - It is the first hibernate object you create in any hibernate application. The hibernate framework layer consists of various objects such as configuration, session factory, session, transaction, query, and criteria. The data flow between the java application and database is done using the hibernate-defined persistent object. In the above diagram, you can see all four layers. The hibernate architecture is categorized into four layers. Hibernate resides between our java application and the database. Hibernate has a layered architecture that helps us to operate without knowing the underlying APIs which implement object-relational mapping. Here we will discuss the components of which hibernate is composed. Hibernate is just an implementation of JPA. In Java, we have a specification called Java Persistence API(JPA) that describes the management of objects in the relational database. This framework is responsible for solving object-relational impedance mismatch problems. It was released in 2001 by Gavin King with colleagues from Cirrus Technologies as an alternative to EJB2 style entity beans. Hibernate is an open-source high-performance object-relational mapping tool for the Java programming language. As parameterized constructor is present, compile will not add any argument constructor on its own therefore you have to do it manually. These classes are nothing but consist of private instance variables, a parameterized constructor with public getters and setters.Īlong with parameterized constructor, the POJO class must have a no-argument public constructor because it is needed by the ORM for serialization purposes. In java, ORM works on plain old java object (POJO) classes whose objects need to be mapped. But for that, we need to do a small configuration to tell the ORM how the objects will be mapped. The answer is no, ORM will do it for us by declaring data types for the columns the same as of instance variables. Now the thing is whether you need to declare a table in the database to store objects. Now the question arises how it is done?īasically, the name of the instance variable is given to the column name and its value forms the row in the relational database. ORM technique converts objects into relational data and vice versa. The name itself suggests the mapping of objects into relational tables. ORM solves the mismatch between the object model and the relational database. Is there any technique through which we can directly store and retrieve objects in a relational database? The answer is yes, you can. Data in the form of objects provide abstraction and portability. But when working with the objects one thing the database does not support is the storage of objects as it stores only relational data. Along with that, databases provide us an efficient way of searching the records so that data can be found easily and quickly. The database stores a large volume of data in one single place. IT industry is today working on object-oriented languages with relational databases as the backbone of the application for storing and retrieving the data.
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