Named querey is a concept which separate the query from coding section to hbm file with a specific name. Which we can use by calling its name. It can be reusable. can be native sql or hql.
We are taking here one simple query , fetching records whose salary<11000.
These are the steps for achieving it
- Create The Employee bean class
package com.bullraider.nsq; import java.io.Serializable; import java.io.Serializable; public class Employee implements Serializable{ private long empno; private String ename; private int sal; private String job; private int deptno ; Employee(){ } public Employee( String ename, String job, int sal,int deptno) { super(); this.deptno = deptno; this.empno = empno; this.ename = ename; this.job = job; this.sal = sal; //this.employeeAddress=employeeAddress; } public long getEmpno() { return empno; } public void setEmpno(long empno) { this.empno = empno; } public String getEname() { return ename; } public void setEname(String ename) { this.ename = ename; } public int getSal() { return sal; } public void setSal(int sal) { this.sal = sal; } public String getJob() { return job; } public void setJob(String job) { this.job = job; } public int getDeptno() { return deptno; } public void setDeptno(int deptno) { this.deptno = deptno; } }
- Design emp.hbm.xml
<?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd"> <hibernate-mapping> <class name="com.bullraider.nsq.Employee" table="emp200"> <meta attribute="class-description"> This class contains employee details. </meta> <id name="empno" type="long" column="empno"> <generator class="native" /> </id> <property name="ename" type="string" column="ename" not-null="true" /> <property name="job" type="string" column="job" not-null="true" /> <property name="sal" type="integer" column="sal" not-null="true" /> <property name="deptno" type="integer" column="deptno" not-null="true" /> </class> <query name="selectEmp"> <![CDATA[ from Employee where sal<11000 ]]> </query> </hibernate-mapping>
- HibernateUtil Class to get the SessionFactory
package com.bullraider.nsq; import org.hibernate.SessionFactory; import org.hibernate.cfg.Configuration; public class HibernateUtil { private static final SessionFactory sessionFactory; static { try { sessionFactory = new Configuration().configure() .buildSessionFactory(); } catch (Throwable ex) { System.err.println("SessionFactory creation failed" + ex); throw new ExceptionInInitializerError(ex); } } public static SessionFactory getSessionFactory() { return sessionFactory; } }
- Create the main class
package com.bullraider.nsq; import java.util.Iterator; import java.util.List; import org.hibernate.HibernateException; import org.hibernate.Query; import org.hibernate.Session; import org.hibernate.Transaction; public class EmployeeDao { public static void main(String[] args) { EmployeeDao dao=new EmployeeDao(); dao.saveEmployee(); dao.retriveEmployee(); } public void saveEmployee() { Session session = HibernateUtil.getSessionFactory().openSession(); Transaction transaction = null; Long empId = null; try { transaction = session.beginTransaction(); Employee emp1=new Employee("Alok","SALESMAN",2000,10); Employee emp2=new Employee("Bhibhu","MGR",2000,20); Employee emp3=new Employee("Ameet","SALESMAN",18000,10); Employee emp4=new Employee("Prasdeep","CLERK",10000,10); session.save(emp1); session.save(emp2); session.save(emp3); session.save(emp4); EmployeeDao dao=new EmployeeDao(); dao.retriveEmployee(); transaction.commit(); System.out.println("Records inserted sucessessfully"); } catch (HibernateException e) { transaction.rollback(); e.printStackTrace(); } finally { session.close(); } } public void retriveEmployee() { Session session = HibernateUtil.getSessionFactory().openSession(); Transaction transaction = null; try { transaction = session.beginTransaction(); System.out.println("HI"); List emp= session.getNamedQuery("selectEmp").list(); System.out.println("Size is"+" "+emp.size()); System.out.println("HI"); for (Iterator iterator = emp.iterator(); iterator.hasNext();) { Employee employee1 = (Employee) iterator.next(); System.out.println(employee1.getEname()+" "+ employee1.getSal()); } transaction.commit(); } catch (HibernateException e) { transaction.rollback(); e.printStackTrace(); } finally { session.close(); } } }
- This is the hibernate.cfg.xml
<?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="hibernate.connection.driver_class">oracle.jdbc.OracleDriver</property> <property name="hibernate.connection.url">jdbc:oracle:thin:@localhost:1521:ORCL</property> <property name="hibernate.connection.username">scott</property> <property name="connection.password">cat</property> <property name="connection.pool_size">1</property> <property name="hibernate.dialect">org.hibernate.dialect.OracleDialect</property> <property name="show_sql">true</property> <property name="hbm2ddl.auto">create-drop</property> <mapping resource="com/bullraider/nsq/Employee.hbm.xml"/> </session-factory> </hibernate-configuration>