projection criteria hibernate Example
In this Example, We will discuss about hibernate criteria query, The class org.hibernate.criterion.Projections is used by applications as a framework for building new kinds of Projection
In this Example, We will discuss about hibernate criteria query, The class org.hibernate.criterion.Projections is used by applications as a framework for building new kinds of Projectionprojection criteria hibernate Example
In this Example, We will discuss about hibernate criteria query, The class org.hibernate.criterion.Projections is used by applications as a framework for building new kinds of Projection. In this example we create a criteria instance and implement the Projections class method.
Here is the simple Example code files.
Criteria_Projection_Example .java
package roseindia;
import java.util.Iterator;
import java.util.List;
import org.hibernate.Criteria;
import org.hibernate.HibernateException;
import org.hibernate.Session;
import org.hibernate.criterion.ProjectionList;
import org.hibernate.criterion.Projections;
import roseindia.bean.User;
import roseindia.util.HibernateUtil;
public class Criteria_Projection_Example {
public static void main(String[] args) {
Session session = HibernateUtil.getSessionFactory().openSession();
User user = null;
try {
Criteria crit = session.createCriteria(User.class);
crit.setMaxResults(5);
ProjectionList proList = Projections.projectionList();
proList.add(Projections.property("empId"));
proList.add(Projections.property("empName"));
proList.add(Projections.property("empAddr"));
proList.add(Projections.property("empSalary"));
crit.setProjection(proList);
List list = crit.list();
Iterator itr = list.iterator();
if (!itr.hasNext()) {
System.out.println("No Data Available!");
} else {
while (itr.hasNext()) {
System.out.printf("\n");
System.out.print("empId : ");
Object[] row = (Object[]) itr.next();
for (int i = 0; i < row.length; i++) {
System.out.print(row[i]);
System.out.printf("\n");
System.out.printf("\t");
}
}
}
} catch (HibernateException e) {
e.printStackTrace();
} catch (Exception e) {
e.printStackTrace();
} finally {
session.flush();
session.close();
}
}
}
The bean class is as follows.
package roseindia.bean;
import java.util.Date;
public class User implements java.io.Serializable {
private static final long serialVersionUID = 1L;
private long empId = 0;
private String empName = null;
private String empAddr = null;
private String empPhone = null;
private String empEmail = null;
private Date empDOB = null;
private int expInMonth = 0;
private double empSalary = 0.0;
public User() {
}
public User(String empName, String empAddr, String empPhone,
String empEmail, Date empDOB, int expInMonth, double empSalary) {
this.empName = empName;
this.empAddr = empAddr;
this.empPhone = empPhone;
this.empEmail = empEmail;
this.empDOB = empDOB;
this.expInMonth = expInMonth;
this.empSalary = empSalary;
}
public long getEmpId() {
return empId;
}
public void setEmpId(long empId) {
this.empId = empId;
}
public String getEmpName() {
return empName;
}
public void setEmpName(String empName) {
this.empName = empName;
}
public String getEmpAddr() {
return empAddr;
}
public void setEmpAddr(String empAddr) {
this.empAddr = empAddr;
}
public String getEmpPhone() {
return empPhone;
}
public void setEmpPhone(String empPhone) {
this.empPhone = empPhone;
}
public String getEmpEmail() {
return empEmail;
}
public void setEmpEmail(String empEmail) {
this.empEmail = empEmail;
}
public Date getEmpDOB() {
return empDOB;
}
public void setEmpDOB(Date empDOB) {
this.empDOB = empDOB;
}
public int getExpInMonth() {
return expInMonth;
}
public void setExpInMonth(int expInMonth) {
this.expInMonth = expInMonth;
}
public double getEmpSalary() {
return empSalary;
}
public void setEmpSalary(double empSalary) {
this.empSalary = empSalary;
}
@Override
public String toString() {
return "User [empAddr=" + empAddr + ", empDOB=" + empDOB
+ ", empEmail=" + empEmail + ", empId=" + empId + ", empName="
+ empName + ", empPhone=" + empPhone + ", empSalary="
+ empSalary + ", expInMonth=" + expInMonth + "]";
}
}
We use the following code to insert the values in the database table using mapping file.
DataInsert.java
package roseindia;
import java.util.Date;
import org.hibernate.HibernateException;
import org.hibernate.Session;
import org.hibernate.Transaction;
import roseindia.bean.User;
import roseindia.util.HibernateUtil;
public class DataInsert {
public static void main(String[] args) {
Session session = HibernateUtil.getSessionFactory().openSession();
Transaction transaction = null;
User user = null;
try {
transaction = session.beginTransaction();
for (int i = 0; i < 10; i++) {
user = new User("Gyan " + i, "NEW DELHI" + i,
"68784654654" + i, "[email protected]" + i, new Date(),
12 * i, 15398.00 * i);
session.save(user);
}
transaction.commit();
} catch (HibernateException e) {
transaction.rollback();
e.printStackTrace();
} finally {
session.close();
}
}
}
The database table mapping is in the file User.hbm.xml and hibernate configuration file is hibernate.cfg.xml.
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>
<!-- Database connection settings -->
<property name="connection.driver_class">com.mysql.jdbc.Driver</property>
<property name="connection.url">jdbc:mysql://localhost:3306/test</property>
<property name="connection.username">root</property>
<property name="connection.password"></property>
<!-- JDBC connection pool (use the built-in) -->
<property name="connection.pool_size">10</property>
<!-- SQL dialect -->
<property name="dialect">org.hibernate.dialect.MySQLDialect</property>
<!-- Enable Hibernate's automatic session context management -->
<property name="current_session_context_class">thread</property>
<!-- Disable the second-level cache -->
<property name="cache.provider_class">org.hibernate.cache.NoCacheProvider</property>
<!-- Echo all executed SQL to stdout -->
<property name="show_sql">true</property>
<!-- Drop and re-create the database schema on startup -->
<property name="hbm2ddl.auto">update</property>
<mapping resource="roseindia/bean/User.hbm.xml" />
</session-factory>
</hibernate-configuration>
The User.hbm.xml file is as follows-
The HibernateUtil.java is as follows, is used to get the SessionFactory object to open session.
package roseindia.util;
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("Initial SessionFactory creation failed." + ex);
throw new ExceptionInInitializerError(ex);
}
}
public static SessionFactory getSessionFactory() {
return sessionFactory;
}
}
This example give the output the values from the table according to the criteria defined.
The structure of the database table is as follows:
The resultent query generated by hibernate is as follows which produces the output as follows
Hibernate: select this_.EMP_ID as y0_, this_.EMP_NAME as y1_, this_.EMP_ADDR as y2_, this_.EMP_SALARY as y3_ from EMPLOYEE this_ limit ?
