Example On Hibernate Pagination With Servlet In Eclipse

Let us see an example on hibernate pagination with servlet..

• when response for request is too large [If we have 1000’s of records in the database] then instead of displaying all records at a time on browser  we can display the response page by page manner using pagination mechanism
• In pagination, initially one page response will be displayed and we will get links for getting the next pages response
• In this servelt & hibernate integration, we are going to display  4 records or 4 objects of products using hibernate for selecting the data and we will get links to display the records of the next pages

Regarding Logic  In Order To Get pagination

• The servlet accepts pageIndex parameter and if the parameter is passed then servlet takes the given number as pageIndex, otherwise the servlet will takes the pageIndex as one [ 1  ]
• Servlet uses Criteria API and the pagination methods of Criteria for loading the records (objects) related to that particular page, and servlet display those records on the browser
• In servlet we use Criteria with projection for finding the total number of records available in the table, and we store that number into the variable
• We will find out the number of hyperlinks required by dividing the total number of records with records per page
• we need to use a loop in order to display the links on the browser, while creating each link,  we use the <a href  /> to servlet url pattern [Hiper reference] and by passing that page nomber as value for pageIndex parameter

Hibernate Pagination Example In Eclipse

Mates, let see one real time example on this hibernate pagination with servlet
files required…

• Pagination.java
• Product.java
• Product.hbm.xml
• hibernate.cfg.xml
• web.xml

Let us see the directory structure  in the Eclipse ..

Servlet is j2ee related application, so just create one application newly unlike previous normal java programs

Open eclipse –> New –>  Dynamic Web Project

 Note:

• src folder contains all *.java files
• build folder contains all *.class files in side classes folder
• Hibernate related xml’s hibernate.cfg.xml, mapping files should be in classes folder only

product.java

public class Product{

	private int productId;
	private String proName;
	private double price;

	public void setProductId(int productId)
	{
	    this.productId = productId;
	}
	public int getProductId()
	{
	    return productId;
	}

	public void setProName(String proName)
	{
	    this.proName = proName;
	}
	public String getProName()
	{
	    return proName;
	}

	public void setPrice(double price)
	{
	    this.price = price;
	}
	public double getPrice()
	{
	    return price;
	}
}

Product.xml

<?xml version="1.0"?>
<!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.java4s.hservlet.pagination.Product" table="products">

<id name="productId" column="pid"  />
<property name="proName" column="pname" length="10"/>
<property name="price"/>

</class>
</hibernate-mapping>

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="connection.driver_class">oracle.jdbc.driver.OracleDriver
</property>
<property name="connection.url">jdbc:oracle:thin:@www.java4s.com:1521:XE</property>
<property name="connection.username">system</property>
<property name="connection.password">admin</property>

<property name="dialect">org.hibernate.dialect.OracleDialect</property>
<property name="show_sql">true</property>
<property name="hbm2ddl.auto">update</property>

<mapping resource="Product.hbm.xml"></mapping>
</session-factory>
</hibernate-configuration>

Pagination.java

import java.io.IOException;
import java.io.PrintWriter;
import java.util.Iterator;
import java.util.List;

import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServlet;

import org.hibernate.Criteria;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.Configuration;
import org.hibernate.criterion.Projections;

public class Pagination extends HttpServlet
{

SessionFactory factory;

//init method started
public void init(ServletConfig config)throws ServletException
{
factory = new Configuration().configure().buildSessionFactory();
System.out.println("Factory has been created....");
}
//init method end

//service method start
public void service(ServletRequest req, ServletResponse res)
throws ServletException,IOException
{
int pageIndex = 0;
int totalNumberOfRecords = 0;
int numberOfRecordsPerPage = 4;

String sPageIndex = req.getParameter("pageIndex");

if(sPageIndex ==null)
{
pageIndex = 1;
}else
{
pageIndex = Integer.parseInt(sPageIndex);
}

Session ses = factory.openSession();
int s = (pageIndex*numberOfRecordsPerPage) -numberOfRecordsPerPage;

Criteria crit = ses.createCriteria(Product.class);
crit.setFirstResult(s);
crit.setMaxResults(numberOfRecordsPerPage);

List l = crit.list();
Iterator it = l.iterator();

PrintWriter pw = res.getWriter();
pw.println("<table border=1>");
pw.println("<tr>");
pw.println("<th>PID</th><th>PNAME</th><th>PRICE</th>");
pw.println("</tr>");

while(it.hasNext())
{
Product p = (Product)it.next();
pw.println("<tr>");
pw.println("<td>"+p.getProductId()+"</td>");
pw.println("<td>"+p.getProName()+"</td>");
pw.println("<td>"+p.getPrice()+"</td>");
pw.println("</tr>");
}

pw.println("<table>");

Criteria crit1 = ses.createCriteria(Product.class);
crit1.setProjection(Projections.rowCount());

List l1=crit1.list();

// pw.println(l1.size());
//returns 1, as list() is used to execute the query if true will returns 1

Iterator it1 = l1.iterator();

if(it1.hasNext())
{
Object o=it1.next();
totalNumberOfRecords = Integer.parseInt(o.toString());
}

int noOfPages = totalNumberOfRecords/numberOfRecordsPerPage;
if(totalNumberOfRecords > (noOfPages * numberOfRecordsPerPage))
{
noOfPages = noOfPages + 1;
}

for(int i=1;i<=noOfPages;i++)
{
String myurl = "ind?pageIndex="+i;
pw.println("<a href="+myurl+">"+i+"</a>");
}

ses.close();
pw.close();

}
//service method end

//destroy method start
public void destroy()
{
factory.close();
}
//destroy end
}

Note:

• We must create the SessionFactory object in the init() only, as it is the heavy weight one
• and nothing to explain, just read slowly. If you got struck at any point just fire a question in our forum, and see line number 101,  ind?pageIndex (ind is my url pattern)

web.xml

<web-app>
<servlet>
<servlet-name>dummyName</servlet-name>
<servlet-class>com.java4s.hservlet.pagination.Pagination</servlet-class>
</servlet>

<servlet-mapping>
<servlet-name>dummyName</servlet-name>
<url-pattern>/ind</url-pattern>
</servlet-mapping>
</web-app>

Output in eclipse:

Right click on the project root — > run –> Run on Server

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::. About the Author .::
		Sivateja Kandula - Java/J2EE Full Stack Developer Founder of Java4s - Get It Yourself, A popular Java/J2EE Programming Blog, Love Java and UI frameworks. You can sign-up for the Email Newsletter for your daily dose of Java tutorials.