Hibernate
Hibernate
• Hibernate is a powerful, high performance
object/relational persistence and query service.
Hibernate lets you develop persistent classes following
object-oriented idiom - including association, inheritance,
polymorphism, composition, and collections. Hibernate
allows you to express queries in its own portable SQL
extension (HQL), as well as in native SQL, or with an
object-oriented Criteria and Example API.
• Unlike many other persistence solutions, Hibernate does
not hide the power of SQL from you and guarantees that
your investment in relational technology and knowledge
is as valid as always. The LGPL open source license
allows the use of Hibernate and NHibernate in open
source and commercial projects.
Java Persistence with Hibernate
• The Java Persistence API is the standard object/relational mapping
and persistence management interface of the Java EE 5.0 platform.
As part of the EJB 3.0 specification effort, it is supported by all major
vendors of the Java industry.
• Hibernate implements the Java Persistence object/relational
mapping and persistence management interfaces with the Hibernate
Annotations and Hibernate EntityManager modules, on top of the
mature and powerful Hibernate Core.
• The Hibernate modules can be stacked and combined as desired.
You can use the Hibernate Java Persistence provider in any
environment, Java SE 5.0 or Java EE 5.0. The Hibernate Java
Persistence provider is fully certified and passes the Sun TCK.
Hibernate Annotations
• Project Lead: Emmanuel BernardLatest release: 3.4.0 GA
(Changelog) (Road Map)Release date: 20.08.2008Requirements:
Hibernate Core 3.3.x, JDK 5.0Hibernate, like all other
object/relational mapping tools, requires metadata that governs the
transformation of data from one representation to the other (and vice
versa). As an option, you can now use JDK 5.0 annotations for
object/relational mapping with Hibernate 3.2. You can use
annotations in addition to or as a replacement of XML mapping
metadata.
• The Hibernate Annotations package includes:
• Standardized Java Persistence and EJB 3.0 (JSR 220)
object/relational mapping annotations
• Hibernate-specific extension annotations for performance
optimization and special mappings
• You can use Hibernate extension annotations on top of standardized
Java Persistence annotations to utilize all native Hibernate features.
More jar file downloads
• You will need persistence and ejb jar files: ejb,
persistence, jndi, geronimo-ejb, ejb3-persistence
and javaee.
• Hibernate tutorials:
• http://www.hibernate.org/hib_docs/reference/en/
html/tutorial.html
• http://www.roseindia.net/hibernate/index.shtml
• http://www.hibernate.org/hib_docs/reference/en/
html/tutorial-webapp.html
• http://www.inf.ed.ac.uk/teaching/courses/ec/han
douts/quickstart.pdf
Hibernate tutorials
• I hope to put two or three tutorials here. Right
now there is just one, an application program
running against a mysql db, with just one table,
using hibernate.
• Hibernate standardizes the db interface. A config
file specifies the actual db service and the
dialect to use, and other config files, called hbm,
map the individual tables. Instead of provider-
specific connection and query details, the
program uses the hibernate “interface” to
interact with the database.
First hibernate tutorial
• Using hibernate with a mysql database and a
few simple java classes.
• Link for tutorial:
http://www.hibernate.org/hib_docs/reference/en/
html/tutorial-firstapp.html
• This tutorial has many omissions, most notably
library jar files needed, also a few errors or typos
about where files go. I also had to modify some
classes (HibernateUtil) somewhat to get it to
work.
ant
• You’ll use ant and a build file appears in the next
slide. If you change directories or file names
you’ll have to make modifications in the ant
script.
• Recall, ant must be in the system path and all
your java stuff must be in the path/classpath for
the ant build to work.
• Note, the build requires directories called src,
bin and lib. Contents are detailed later.
build.xml
Notes about lib directory
• You’ll need the following jars:
– hibernate
– cp30
– antlr
– jta
– dom4j
– commons logging and collections
– Just 2 files from slf4j(simple and api)…note screen
shot!!!
– You won’t need hsqldb – that’s another db service
connector, but you will need the mysql-java db
connector
My lib directory
Directory structure
• Your_App_dir
– bin
– src
• log4j.properties
• hibernate.cfg.xml
• Event.hbm.xml
• hibernate.properties --- not included in this example
• events(dir)
– Event.java
• util(dir)
– EventManager.java
– HibernateUtil.java
– Lib (see previous slide)
HibernateUtil.java
package util;
//you can find this class in eclipse, netbeans or online, with few variations
import org.hibernate.*;
import org.hibernate.cfg.*;
public class HibernateUtil {
private static final SessionFactory sessionFactory;
static {
try {
System.out.println("in try for build session factory");
// Create the SessionFactory from hibernate.cfg.xml
sessionFactory = new Configuration().configure().buildSessionFactory();
System.out.println("back from build session factory");
} catch (Throwable ex) {
// Make sure you log the exception, as it might be swallowed
System.err.println("Initial SessionFactory creation failed." + ex);
System.out.println("Initial SessionFactory creation failed." + ex);
throw new ExceptionInInitializerError(ex);
} }
public static SessionFactory getSessionFactory() {
return sessionFactory; }}
EventManager.java entirety also in slide notes
package events;
import org.hibernate.*;
import org.hibernate.cfg.*;
import java.util.Date;
import java.util.*;
import util.HibernateUtil;
public class EventManager {
public static void main(String[] args) {//main
EventManager mgr = new EventManager();
System.out.println("Event Manager before if") ; /////I stuck in all these println
if (args[0].equals("store")) {//if
System.out.println("create and store");
mgr.createAndStoreEvent("My Event", new Date());
}//if
else if (args[0].equals("list")) {
System.out.println("list events");
List events = mgr.listEvents();
for (int i = 0; i
hibernate.cfg.xml contains connection info,
db name, user name & pw and other
information
com.mysql.jdbc.Driver
jdbc:mysql://localhost/mydb
root
10
org.hibernate.dialect.MySQLDialect
true
update
Log4j.properties
log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.Target=System.out
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern=%d{ABSOLUTE} %5p
%c{1}:%L - %m%n
log4j.rootLogger=info, stdout
log4j.logger.org.hibernate.test=info
log4j.logger.org.hibernate.tool.hbm2ddl=debug
remark
• You’ll need to create a mysql database
and table for this example and you need to
start the database server before running
the example.
• Run the example in the root directory on
the commandline either with
ant run –Daction=store
• Or
ant run –Daction=list
black screen output for store (when it works)
C:\hibernateexample>ant run -Daction=store
Buildfile: build.xml
clean:
[delete] Deleting directory C:\hibernateexample\bin
[mkdir] Created dir: C:\hibernateexample\bin
copy-resources:
[copy] Copying 6 files to C:\hibernateexample\bin
[copy] Copied 2 empty directories to 1 empty directory under C:\hibernateex
ample\bin
compile:
[javac] Compiling 3 source files to C:\hibernateexample\bin
run:
[java] Event Manager before if
[java] create and store
[java] Event Manager... create and store method
[java] in try for build session factory
>>
[java] 719 [main] INFO org.hibernate.tool.hbm2ddl.SchemaUpdate - schema upd
ate complete
[java] back from build session factory
[java] .. before begin transaction
[java] .. transaction started
[java] Hibernate: insert into EVENTS (EVENT_DATE, title) values (?, ?)
[java] session save completed
[java] after commit in create and save
[java] 907 [main] INFO org.hibernate.impl.SessionFactoryImpl - closing
[java] 907 [main] INFO org.hibernate.connection.DriverManagerConnectionProv
ider - cleaning up connection pool: jdbc:mysql://localhost/mydb
[java] Event Manager: completed if
BUILD SUCCESSFUL
Total time: 2 seconds
C:\hibernateexample>
Run –list when it works…entirety in notes
C:\hibernateexample>ant run -Daction=list
Buildfile: build.xml
clean:
…
copy-resources:
…
compile:
[javac] Compiling 3 source files to C:\hibernateexample\bin
run:
>>>
[java] 531 [main] INFO org.hibernate.impl.SessionFactoryImpl - building ses
sion factory
[java] 719 [main] INFO org.hibernate.impl.SessionFactoryObjectFactory - Not
binding factory to JNDI, no JNDI name configured
[java] 719 [main] INFO org.hibernate.tool.hbm2ddl.SchemaUpdate - Running hb
m2ddl schema update
[java] 719 [main] INFO org.hibernate.tool.hbm2ddl.SchemaUpdate - fetching d
atabase metadata
[java] 719 [main] INFO org.hibernate.tool.hbm2ddl.SchemaUpdate - updating s
chema
[java] 734 [main] INFO org.hibernate.tool.hbm2ddl.TableMetadata - table fou
nd: mydb.events
[java] 734 [main] INFO org.hibernate.tool.hbm2ddl.TableMetadata - columns:
- schema update complete
[java] back from build session factory
[java] Hibernate: select event0_.EVENT_ID as EVENT1_0_, event0_.EVENT_DATE
as EVENT2_0_, event0_.title as title0_ from EVENTS event0_
[java] Event: My Event Time: 2009-03-03 00:00:00.0
[java] 1062 [main] INFO org.hibernate.impl.SessionFactoryImpl - closing
[java] Event Manager: completed if
[java] 1062 [main] INFO org.hibernate.connection.DriverManagerConnectionPro
vider - cleaning up connection pool: jdbc:mysql://localhost/mydb
BUILD SUCCESSFUL
Total time: 2 seconds
C:\hibernateexample>
Your project
notes
• First, of course, get the original tutorial working.
• Modify the EventManager so it opens a JFrame with two
button, list and store, a textfield and a textarea.
• You are welcome to make a different table but you don’t
have to.
• (E.C. You may want another button to delete * from
db/table)
• List button will display stored events in a textarea.
• Store button will get data for the event from a textfield.
• E.C. The tutorial code uses a timestamp, but maybe
something else like a string with MM/DD/YY format
would be nicer.
So what’s the point of hibernate?
• A uniform connection (that session thingy)
and sql dialect in your object. This doesn’t
change as you port your application.
• The hibernate.cfg.xml (NOT your java
code) gets modified if you port your app,
or change database servers.
The hibernate webapp
WEB-INF\web.xml
Event Manager
events.EventManagerServlet
Event Manager
/eventmanager
Where do files go? Shown in
another slide but note…
• Hibernate.cfg goes in classes dir
• Event.hbm.xml goes into Events dir (I
think)
The 1-table hibernate web app
• http://www.hibernate.org/hib_docs/reference/e
n/html/tutorial-webapp.html
• This tutorial came from hibernate.org. I think it is
basically correct, although I made changes to
the servlet trying to fix unrelated problems. I also
used my own HibernateUtil class (shown in
previous tutorial).
• Not very many details about the directory
structure were given in the tutorial, but I give
them here.
Servlet running in tomcat
Servlet entirety in slide notes
package events;
import java.io.*;
import java.net.*;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Iterator;
import java.util.List;
import javax.servlet.*;
import javax.servlet.http.*;
import util.HibernateUtil;
import org.hibernate.*;
public class EventManagerServlet extends HttpServlet {
SessionFactory sessionFactory;
Session session;
Servlet continued
protected void processRequest(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("text/html;charset=UTF-8");
SimpleDateFormat dateFormatter = new SimpleDateFormat("dd.MM.yyyy");
PrintWriter out = response.getWriter();
out.println("Event Manager");
try {
// Begin unit of work
// HibernateUtil.getSessionFactory().getCurrentSession().beginTransaction();
sessionFactory = HibernateUtil.getSessionFactory();
session =sessionFactory.openSession();
session.beginTransaction();
// Handle actions
if ("store".equals(request.getParameter("action"))) {
String eventTitle = request.getParameter("eventTitle");
String eventDate = request.getParameter("eventDate");
if ("".equals(eventTitle) || "".equals(eventDate)) {
out.println("Please enter event title and date.");
} else {
System.out.println("before call to create and store");
createAndStoreEvent(eventTitle, dateFormatter.parse(eventDate));
out.println("Added event."); } }
printEventForm(out);
listEvents(out, dateFormatter);
// End unit of work
//HibernateUtil.getSessionFactory().getCurrentSession().getTransaction().commit();
session.getTransaction().commit();
System.out.println("commit after save");
} catch (Exception ex) {
HibernateUtil.getSessionFactory().getCurrentSession().getTransaction().rollback();
throw new ServletException(ex);
}
}
Servlet continued
private void printEventForm(PrintWriter out) {
out.println("Add new event:");
out.println("");
out.println("Title: ");
out.println("Date (e.g. 24.12.2009): ");
out.println("");
out.println("");
}
private void listEvents(PrintWriter out, SimpleDateFormat dateFormatter) {
List result = HibernateUtil.getSessionFactory().getCurrentSession().createCriteria(Event.class).list();
if (result.size() > 0) {
out.println("Events in database:");
out.println("");
out.println("");
out.println("Event title");
out.println("Event date");
out.println("");
for (Iterator it = result.iterator(); it.hasNext();) {
Event event = (Event) it.next();
out.println("");
out.println("" + event.getTitle() + "");
out.println("" + dateFormatter.format(event.getDate()) + "");
out.println("");
}
out.println("");
}
}
Servlet continued
protected void createAndStoreEvent(String title, Date theDate) {
Event theEvent = new Event();
theEvent.setTitle(title);
theEvent.setDate(theDate);
HibernateUtil.getSessionFactory().getCurrentSession().save(theEvent);
}
protected void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
processRequest(request, response);
}
protected void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
processRequest(request, response);
}
}
One line added to cfg
com.mysql.jdbc.Driver
jdbc:mysql://localhost/mydb
root
10
org.hibernate.dialect.MySQLDialect
true
update
thread
This build puts webapp war file one directory up
(like in C:)
Package things in WEB-INF as
shown here
• WEB-INF
– classes (dir)
• events(dir)
– Event.class (no changes to this file)
– EventManagerServlet.class
– Event.hbm.xml (no changes to this file)
• util(dir)
– HibernateUtil.class (this file same as in previous project)
• Hibernate.cfg.xml (shown above – one line added)
• If it can’t find tableclass.hbm.xml then put them here
– lib(dir) (no changes to this)
– log4j.properties(no changes to this)
– web.xml (shown above)
Jar
• I used jar instead of ant build:
jar –cvf appname.war WEB-INF
Creates a jar called appname.war from
contents of WEB-INF
You’ll need to move files and directories as
per earlier slide before creating a war file.
What’s next?
• I will put a 2nd hibernate project here to be
assigned after the hibernate desktop app. I
haven’t finished working on it, but it will
likely involve CRUD against a database
using one or more servlets, like your
servlet database project, except use a
hibernate interface.
Two examples: multiple tables & crud
• documentation
http://www.hibernate.org/hib_docs/referen
ce/en/html/
Adding to tables & listing
• I modified previous example, adding a
people table and displaying contents of
two tables.
• I did not do a select, I just printed the
event title in the same position. But since
the numbers are allocated sequentially, I
could have used select title from Event
where id=number
My tables
• My People table and my Event table both
have ids as primary key, autoincremented.
• In the hbm, these are identified as
Dir structure
• WEB-INF
– log4j.properties
– web.xml
– lib (contents shown later)
– classes
• hibernate.cfg.xml
• util
– Same HibernateUtil.java as previous
• events
– Same Event.java as previous
– People.java
– EventManagerServlet.java
– People.hbm.xml
– Event.hbm.xml (unchanged from prev example)
some of these may be unnecessary
but I whittled it down some
Entire Servlet in notes
package events;
import java.io.*;
import java.net.*;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Iterator;
import java.util.List;
import javax.servlet.*;
import javax.servlet.http.*;
import util.HibernateUtil;
import org.hibernate.*;
public class EventManagerServlet extends HttpServlet {
SessionFactory sessionFactory;
List result1,result2;
Session session;
protected void processRequest(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("text/html;charset=UTF-8");
SimpleDateFormat dateFormatter = new SimpleDateFormat("dd.MM.yyyy");
PrintWriter out = response.getWriter();
out.println("Event Manager");
try {
// Begin unit of work
// HibernateUtil.getSessionFactory().getCurrentSession().beginTransaction();
sessionFactory = HibernateUtil.getSessionFactory();
session =sessionFactory.openSession();
session.beginTransaction();
Servlet…print form, get session
// Handle actions
if ("store".equals(request.getParameter("action"))) {
String eventTitle = request.getParameter("eventTitle");
String eventDate = request.getParameter("eventDate");
String name = request.getParameter("name");
String phone = request.getParameter("phone");
if ("".equals(eventTitle) || "".equals(eventDate)||name.equals("")||phone.equals("")) {
out.println("Please enter person, event title and date.");
} else {
System.out.println("before call to create and store");
createAndStoreEvent(name, phone,eventTitle, dateFormatter.parse(eventDate));
out.println("Added event.");
}
}
// Print page
printEventForm(out);
System.out.println("back in process ...about to call listevents");
listEvents(out, dateFormatter);
// End unit of work
//HibernateUtil.getSessionFactory().getCurrentSession().getTransaction().commit();
session.getTransaction().commit();
System.out.println("commit after save");
} catch (Exception ex) {
System.out.println(ex.toString());
HibernateUtil.getSessionFactory().getCurrentSession().getTransaction().rollback();
throw new ServletException(ex);
}
}
Servlet: the form and table of events
private void printEventForm(PrintWriter out) {
out.println("Add new event:");
out.println("");
out.println("Title: ");
out.println("Date (e.g. 24.12.2009): ");
out.println("Contact person: ");
out.println("Phone(e.g. (123) 432-1111: ");
out.println("");
out.println("");
}
private void listEvents(PrintWriter out, SimpleDateFormat dateFormatter) {
result1 = session.createCriteria(Event.class).list();
if (result1.size() > 0) {
out.println("Event Info in database:");
out.println("");
out.println("");
out.println("Event title");
out.println("Event date");
out.println("Event id");
out.println("");
for (Iterator it = result1.iterator(); it.hasNext();) {
Event event = (Event) it.next();
out.println("");
out.println("" + event.getTitle()+ "");
out.println("" + dateFormatter.format(event.getDate()) + "");
out.println("" + event.getId() + "");
out.println("");
}
out.println("");
}//if
Servlet… list table of people
int num=0;
result2 = session.createCriteria(People.class).list();
if (result2.size() > 0) {
out.println("People Info in database:");
out.println("");
out.println("");
out.println("Person");
out.println("Phone");
out.println("Event coordinating");
out.println("");
String unknown="unknown";
for (Iterator it = result2.iterator(); it.hasNext();) {
People person=(People)it.next();
out.println("");
out.println("" + person.getName() + "");
out.println("" + person.getPhone() + "");
out.println("" + ((Event)result1.get(num)).getTitle() + "");
num++;
out.println("");
}
out.println("");
}
}
Create and store
protected void createAndStoreEvent(String name,String phone,String title, Date theDate) {
System.out.println("in create and store method");
Event theEvent = new Event();
People person=new People();
theEvent.setTitle(title);
theEvent.setDate(theDate);
person.setName(name);
person.setPhone(phone);
System.out.println("about to get current session and save event");
session.save(theEvent);
System.out.println("about to get current session and save person");
session.save(person);
System.out.println("done with saves");
}
protected void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
System.out.println("in do get");
processRequest(request, response);
}
protected void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
System.out.println("in do post");
doGet(request, response);
}
}
events.People.java
public class People{
private String name;
private String phone;
private long id;
public People() {}
public long getId(){return id;}
public void setId(long id){this.id=id;}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getPhone() {
return phone;
}
public void setPhone(String phone) {
this.phone = phone;
}
}
The primary key may be generated, native or
assigned. The strategy must be specified in the
hbm.xml. This is People.hbm.xml
Same hibernate.cfg.xml except
People table has been added.
com.mysql.jdbc.Driver
jdbc:mysql://localhost/mydb
root
10
org.hibernate.dialect.MySQLDialect
org.hibernate.cache.NoCacheProvider
true
update
thread
ant build – still needs to be modified to build
WEB-INF and classes dirs, and copy files to
there, then jar
CRUD example
• The student table
Hibernate student info servlet
remarks
• Just one table marked
• Link above gives good information on how
to conduct queries.
• I used radiobuttons to indicate function
desired.
• I used the same ant/build and jar
commands as before.
• Same directory structure.
• Servlet in slide notes
Student.hbm.xml
Some bits of the servlet
try {
// Begin unit of work
// HibernateUtil.getSessionFactory().getCurrentSession().beginTransaction();
sessionFactory = HibernateUtil.getSessionFactory();
session =sessionFactory.openSession();
session.beginTransaction();
if ("store".equals(request.getParameter("action"))) {
String name = request.getParameter("name");
String gpa = request.getParameter("gpa");
String year = request.getParameter("year");
String age = request.getParameter("age");
String sex = request.getParameter("sex");
if ("".equals(name) || "".equals(sex)||year.equals("")||gpa.equals("")||age.equals("")) {
out.println("Please enter name, age, sex, gpa, year and sex.");
} else {
System.out.println("before call to create and store");
createAndStoreEvent(name, age,year,sex,gpa);
out.println("Added event."); } }
else if ("list".equals(request.getParameter("action"))) {
// Print page
System.out.println("back in process ...about to call listevents");
listStudents(out);
}
Delete action
else if ("delete".equals(request.getParameter("action"))) {
String name = request.getParameter("name");
List marked=session.createQuery("from Student as
student where student.name=?").setString(0,name).list();
if(marked.size()>0){
Student student=(Student)marked.get(0);
out.println("deleting...."+ student.getName());
session.delete(student);
}
else {out.println("no match found");}
}else{//update
String name = request.getParameter("name");
String gpa = request.getParameter("gpa");
String year = request.getParameter("year");
String age = request.getParameter("age");
String sex = request.getParameter("sex");
List marked=session.createQuery("from Student as student where
student.name=?").setString(0,name).list();
if(marked.size()>0&&!"".equals(sex)&&!year.equals("")&&!gpa.equals("")&&!age.equal
s("")) {
Student student=(Student)marked.get(0);
student.setAge(Integer.parseInt(age));
student.setYear(year);
student.setGpa(Double.parseDouble(gpa));
student.setSex(sex);
session.update(student);
}
else {out.println("no match found");}
}
/*else a getinfo choice could look about the same
*/
I used radiobuttons
private void printStudentForm(PrintWriter out) {
out.println("Student info form:");
out.println("");
out.println("Name: ");
out.println("Age: ");
out.println("Sex(Male/Female): ");
out.println("Year: ");
out.println("GPA: ");
out.println(" List");
out.println("
Store");
out.println(" Update");
out.println(" Delete");
out.println("");
out.println("");
}
List students
private void listStudents(PrintWriter out) {
result1 = session.createCriteria(Student.class).list();
if (result1.size() > 0) {
out.println("Student Info:");
out.println("");
out.println("");
out.println("Student name");
out.println("Student Age");
out.println("GPA");
out.println("Sex");
out.println("Year");
out.println("");
for (Iterator it = result1.iterator(); it.hasNext();) {
Student student = (Student) it.next();
out.println("");
out.println("" + student.getName()+ "");
out.println("" + student.getAge() + "");
out.println("" + student.getGpa() + "");
out.println("" + student.getSex() + "");
out.println("" + student.getYear() + "");
out.println("");
}
out.println("");
}//if
}
Hibernate configuration
com.mysql.jdbc.Driver
jdbc:mysql://localhost/mydb
root
10
org.hibernate.dialect.MySQLDialect
true
update
web-xml
StudentInfo
data.StudentInfoServlet
StudentInfo
/studentinfo