![]() ![]() }File net\codejava\hibernate\User.java: package Public void addUser(User user) = "GROUP_ID") Using Annotations for Many-to-Many AssociationTo use JPA annotations to map the many-to-many association, create two model classes called Group.java and User.java with the following source code:File net\codejava\hibernate\Group.java: package Here, we specify only two dependencies for Hibernate core and MySQL Connector/J, and the rest will be resolved automatically by Maven, such as Hibernate JPA and Hibernate Commons Annotations.ģ. Ī sample project that demonstrates using JPA annotations to map Hibernate XML configuration file: įor the JAR files required for Hibernate and MySQL-Java library, update the pom.xml file with the following content.Model classes: Group.java and User.java.Creating Maven-Eclipse ProjectIn Eclipse IDE, create a Maven project named HibernateMany2ManyAnnotationsExample with the following structure: This project consists of the following files: ) The usersdb database would have the following structure:Ģ. `group_id` int(11) NOT NULL AUTO_INCREMENT,ĬONSTRAINT `fk_user` FOREIGN KEY (`user_id`) REFERENCES `users` (`user_id`),ĬONSTRAINT `fk_group` FOREIGN KEY (`group_id`) REFERENCES `groups` (`group_id`) `user_id` int(11) NOT NULL AUTO_INCREMENT, Creating Database and TablesThe following MySQL script is used to create a database called usersdb with three tables: groups, users and users_groups (join table): create database usersdb Using Annotations for Many-to-Many Associationġ.A join table ( users_groups) is required to connect the both sides.To develop the sample program, we use the following pieces of software programs and libraries (you can use newer versions): Using annotations is an alternate approach (and preferred) to the XML descriptor one: Hibernate Many-to-Many XML Mapping Example.Let’s recall about a typical many-to-many association: Here, the multiplicity between the groups and users table is many-to-many, meaning that a group can have many users and vice-versa, a user can belong to many groups. In this Hibernate tutorial, we are going to illustrate how to use JPA annotations to map a many-to-many association (both bidirectional and unidirectional) with a sample program developed using Eclipse and Maven.
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