Hibernate CRUD using Oracle

CRUD Operations Using Hibernate 5 & Oracle

 Hibernate is Java based ORM tool that provides a framework for mapping application domain objects to the relational database tables and vice versa. It provides reference implementation of Java Persistence API, that makes it a great choice as an ORM tool with benefits of loose coupling

Framework provides option to map plain old Java objects to traditional database tables with the use of JPA annotations as well as XML based configuration.

A CRUD operation deals with creating, retrieving, updating, and deleting records from the table. In this tutorial we will see how it is done using Hibernate annotations. We are going to discuss 4 main functionalities:

1. Create a record
2. Read a record
3. Update a Record
4. Delete a Record 

Following script will create table,Sequence & Trigger in Oracle 11g

CREATE TABLE student ( id number(11) NOT NULL,   first_name varchar2(50) default null,   last_name varchar2(50) default null,   email varchar2(50) default null,  CONSTRAINT student_pk PRIMARY KEY (id) ); //To create Id as auto increment,we need to sequence & trigger CREATE SEQUENCE student_seq START WITH 1; CREATE OR REPLACE TRIGGER student_bir BEFORE INSERT ON student FOR EACH ROW BEGIN   SELECT student_seq.NEXTVAL   INTO   :new.id   FROM   dual; END; / select * from  student;

Annotation	Modifier	Description
@Entity		Marks a class as a Hibernate Entity (Mapped class)
@Table	Name	Maps this class with a database table specified by name modifier. If the name is not supplied it maps the class with a table having the same name as the class.
@Id		Marks this class field as a primary key column.
@GeneratedValue		Instructs database to generate a value for this field automatically.
@Column	Name	Maps this field with table column specified by name and uses the field name if name modifier is absent.

Project Creation

create a Java based Maven project with Eclipse 

 

SessionFactory

• Reads the hibernate config file
• Creates Session objects
• Heavy-weight object
• Only create once in your app

Session

• Wraps a JDBC connection
• Main object used to save/retrieve object
• short-lived object
• Retrived from SessionFactory

Maven Dependencies

<project xmlns="http://maven.apache.org/POM/4.0.0"        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"        xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">        <modelVersion>4.0.0</modelVersion>        <groupId>Hibernate</groupId>        <artifactId>HibernateDemo</artifactId>        <version>0.0.1-SNAPSHOT</version>        <packaging>jar</packaging>        <name>HibernateDemo</name>        <url>http://maven.apache.org</url>        <properties>              <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>        </properties>        <dependencies>              <!-- https://mvnrepository.com/artifact/org.hibernate/hibernate-core -->              <dependency>                     <groupId>org.hibernate</groupId>                     <artifactId>hibernate-core</artifactId>                     <version>5.3.7.Final</version>              </dependency>        </dependencies>        <repositories>              <repository>                     <id>codelds</id>                     <url>https://code.lds.org/nexus/content/groups/main-repo</url>              </repository>        </repositories> </project>

Create a record 

Hibernate Configuration File

<?xml version='1.0' encoding='UTF-8'?> <!DOCTYPE hibernate-configuration PUBLIC           "-//Hibernate/Hibernate Configuration DTD 3.0//EN"           "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd"> <hibernate-configuration>     <session-factory>        <!--  <property name="hbm2ddl.auto">update</property>  -->         <property name="dialect">org.hibernate.dialect.Oracle10gDialect</property>         <property name="connection.url">jdbc:oracle:thin:@localhost:1521:xe</property>         <property name="connection.username">SYSTEM</property>         <property name="connection.password">oracle</property>         <property name="connection.driver_class">oracle.jdbc.driver.OracleDriver</property>                 <property name="connection.pool_size">1</property>         <property name="show_sql">true</property>         <property name="current_session_context_class">thread </property>     <!-- <mapping resource="EMP.hbm.xml"/> -->     </session-factory> </hibernate-configuration>

  

ID Generation Strategies

GenerationType.AUTO           = Pick an appropriate strategy for the particular database

GenerationType.IDENTITY   = Assign primary keys using a database identity column

GenerationType.SEQUENCE = Assign primary keys using a database sequence

GenerationType.TABLE         = Assign primary keys using an underlying

                                                  database table to ensure uniqueness

 

Implementation of Model Class

package com.hibernate.entity; import javax.persistence.Column; import javax.persistence.Entity; import javax.persistence.Id; import javax.persistence.Table; @Entity @Table(name = "student") public class Student {        @Id        @Column(name = "id")        private int id;        @Column(name = "first_name")        private String firstname;        @Column(name = "last_name")        private String lastname;        @Column(name = "email")        private String email;        public Student(String firstname, String lastname, String email) {              super();              this.firstname = firstname;              this.lastname = lastname;              this.email = email;        }        public int getId() {              return id;        }        public void setId(int id) {              this.id = id;        }        public String getFirstname() {              return firstname;        }        public void setFirstname(String firstname) {              this.firstname = firstname;        }        public String getLastname() {              return lastname;        }        public void setLastname(String lastname) {              this.lastname = lastname;        }        public String getEmail() {              return email;        }        public void setEmail(String email) {              this.email = email;        }        @Override        public String toString() {              return "Student [id=" + id + ", firstname=" + firstname + ", lastname=" + lastname + ", email=" + email + "]";        } }

 

Implementation of DAO Class

package Hibernate.HibernateDemo; import org.hibernate.Session; import org.hibernate.SessionFactory; import org.hibernate.Transaction; import org.hibernate.cfg.Configuration; import com.hibernate.entity.Student; public class CreateStudentDemo {        public static void main(String[] args) {              // create session factory              SessionFactory factory = new Configuration().configure().addAnnotatedClass(Student.class).buildSessionFactory();              // create session              Session session = factory.getCurrentSession();              // create a student object              Student tempstu = new Student("Devyan", "Thakur", "devyan@newton.com");              /*               * // save student object session.save(tempstu);               *               *               * //commit transaction session.getTransaction().commit();               *               * System.out.println("Done!");               */              // creating transaction object              Transaction t = session.beginTransaction();              // persisting the object              session.persist(tempstu);              // commit transaction              t.commit();              session.close();              factory.close();              System.out.println("successfully saved");        } }

 

 Output:

INFO: HHH000182: No default (no-argument) constructor for class: com.hibernate.entity.Student (class must be instantiated by Interceptor)

Hibernate: insert into student (email, first_name, last_name, id) values (?, ?, ?, ?)

successfully saved

  Read a record

 

package Hibernate.HibernateDemo; import java.util.ArrayList; import java.util.List; import org.hibernate.Query; import org.hibernate.Session; import org.hibernate.SessionFactory; import org.hibernate.Transaction; import org.hibernate.cfg.Configuration; import com.hibernate.entity.Student; public class ReadStudentdemo {      static Session session;      static SessionFactory sessionFactoryObj;      public static List<Student> displayRecords() {            List studentsList = new ArrayList();            // create session factory            SessionFactory factory = new Configuration().configure().addAnnotatedClass(Student.class).buildSessionFactory();            // create session            session = factory.getCurrentSession();            // Getting Transaction Object From Session Object            session.beginTransaction();            studentsList = session.createQuery("FROM Student").list();            session.close();            factory.close();            System.out.println("successfully Retrived");            return studentsList;      }      public static void main(String[] args) {            List<Student> viewstudent = ReadStudentdemo.displayRecords();            for (Student s : viewstudent) {                 System.out.println("Student id:" + s.getId() + "Student Name:" + s.getFirstname());            }      } }

Output:

INFO: HHH10001008: Cleaning up connection pool [jdbc:oracle:thin:@localhost:1521:xe]
successfully Retrived
Student id:1Student Name:Paul
Student id:2Student Name:Devyan
Student id:7Student Name:Rahul

Update a Record

package Hibernate.HibernateDemo; import org.hibernate.Session; import org.hibernate.SessionFactory; import org.hibernate.cfg.Configuration; import com.hibernate.entity.Student; public class UpdateStudentRecord {      static Session session;      static SessionFactory sessionFactoryObj;      public static void updateStudent(int student_id) {            // create session factory            SessionFactory factory = new Configuration().configure().addAnnotatedClass(Student.class).buildSessionFactory();            // create session            session = factory.getCurrentSession();            // Getting Transaction Object From Session Object            session.beginTransaction();            //Creating Transaction Entity            Student stu=session.get(Student.class, student_id);            stu.setFirstname("Harendera");                       //committing the transaction to the database            session.getTransaction().commit();            session.close();            factory.close();      }      public static void main(String[] args) {            int updateId=1;            UpdateStudentRecord.updateStudent(updateId);      } }

 

 Output:

INFO: HHH000400: Using dialect: org.hibernate.dialect.Oracle10gDialect Hibernate: select student0_.id as id1_0_0_, student0_.email as email2_0_0_, student0_.first_name as first_name3_0_0_, student0_.last_name as last_name4_0_0_ from student student0_ where student0_.id=? Hibernate: update student set email=?, first_name=?, last_name=? where id=? Oct 30, 2018 9:24:49 AM org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl stop INFO: HHH10001008: Cleaning up connection pool [jdbc:oracle:thin:@localhost:1521:xe]

Delete a Record 

package Hibernate.HibernateDemo; import org.hibernate.Session; import org.hibernate.SessionFactory; import org.hibernate.cfg.Configuration; import com.hibernate.entity.Student; public class DeleteStudentRecord {      static Session session;      static SessionFactory sessionFactoryObj;           public static void deleteStudent(int student_id) {            // create session factory            SessionFactory factory = new Configuration().configure().addAnnotatedClass(Student.class).buildSessionFactory();            // create session            session = factory.getCurrentSession();            // Getting Transaction Object From Session Object            session.beginTransaction();            // Creating Transaction Entity            Student stu = session.get(Student.class, student_id);            session.delete(stu);            // committing the transaction to the database            session.getTransaction().commit();            session.close();            factory.close();      }           public static void main(String[] args) {            int id=1;            DeleteStudentRecord.deleteStudent(id);      } }

Output:

INFO: HHH000400: Using dialect: org.hibernate.dialect.Oracle10gDialect Hibernate: select student0_.id as id1_0_0_, student0_.email as email2_0_0_, student0_.first_name as first_name3_0_0_, student0_.last_name as last_name4_0_0_ from student student0_ where student0_.id=? Hibernate: delete from student where id=? Oct 30, 2018 10:41:52 AM org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl stop INFO: HHH10001008: Cleaning up connection pool [jdbc:oracle:thin:@localhost:1521:xe]

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