R4R provide basic Hibernate Tutorials concept with
Hibernate Examples .
Through R4R you can develop Hibernate programming concept. R4R provide
Hibernate Interview Questions with answers. R4R provide
Hibernate Languages study materials in easy way.
HIBERNATE
Hibernate is a java package that makes it easy to work with
relational database. Hibernate is an object-relational
mapping (ORM) library for the Java language, providing a framework for mapping an object-oriented
domain model to a traditional relational database. Hibernate provides a solution
to map database tables to a class. It copies the database data to a
class. In the other direction it supports to save objects to the database. In
this process the object is transformed to one or more tables.
Hibernate solves object-relational impedance mismatch
problems by replacing direct persistence-related database accesses with high-level object
handling functions. The primary feature of hibernate is
mapping from java classes to database tables and from java data types to
Sql data types.
Hibernate generates the SQL calls
and attempts to relieve the developer from manual result set handling and object
conversion and keep the application portable to all supported SQL databases with little
performance overhead. Two terms need to be understand in hibernate is
Persistence and Mapping.
Persistence: Saving
data to a storage is called persistence. Hibernate provides transparent
persistence for Plain Old Java Objects (POJOs).
persistent class is a no-argument
constructor, not public.
Persistence frame work:persistence
frame work moves the data in its natural form to and from the permanent storage
of data i.e. database
Hibernate is a powerful, ultra-high performance
object/relational persistence and query service for Java.
Mapping: Copying of
tables to object and objects to table is called object relational mapping.
using object relational mapping you can reuse your code. you can
separate your dialog from your logic ,and logic from persistence mechanism.
Mapping Java classes to database tables is accomplished through
the configuration of an XML file or by using Java Annotations.
Hibernate supports the mapping of custom value types. which
makes the following scenario possible:
1.Mapping a single property to multiple columns
2.Mapping Java Enum to columns as if they were regular properties.
3.Overriding the default SQL type that Hibernate chooses when mapping a
column to a property.
WHAT IS HIBERNATE QUERY LANGUAGE
Hibernate introduced a SQL inspired language called
Hibernate Query Language (HQL). ) which allows
SQL-like queries to be written against Hibernate's data objects.
HIBERNATE INTEGRATE PROGRAMMING
LANGUAGES
Hibernate can be used both in standalone
Java applications and in
Java EE applications using servlets or EJB
session beans. It can also be included as a feature in other
programming languages.
HISTORY OF HIBERNATE
Hibernate was started in 2001
by Gavin King as an alternative to
using EJB2-style entity beans. Its mission
back then was to simply offer better persistence capabilities than offered by EJB2 by simplifying the
complexities and allowing for missing features.
Early in 2003, the Hibernate development team began Hibernate2 releases
which offered many significant improvements over the first release and would go on to catapult Hibernate as the "de facto"
standard for persistence in Java.
The current version of Hibernate is
Version 3.x. This version introduced new features like a new
Interceptor/Callback architecture, user defined filters, and JDK 5.0 as of 2010 Hibernate 3 (version 3.5.0
and up) is a certified implementation of the Java Persistence API 2.0 specification via a wrapper for the Core module which provides
conformity with the JSR.
HIBERNATE APIs
Hibernate application interface programming are present in the
java package org.hibernate. Two interfaces are present in org.hibernate package
1.org.hibernate.SessionFactory
interface:-References immutable and threadsafe object creating new
Hibernate sessions. Hibernate-based
applications are usually designed to make use only of a single
instance of the class implementing this interface .
2.org.hibernate.Session interface:-Represents
a Hibernate session i.e. the main point of the manipulation performed on the
database entities. The latter activities include (among the other things) managing the
persistence state (transient, persisted, detached) of the objects, fetching the
persisted ones from the database and the management of the transaction
demarcation.
WHY SHOULD ONE CAN USE HIBERNATE
Hibernate provide important features of it that's why it
is good to use hibernate.
1.Performance: Hibernate can save your time and
efforts, and it can let you achieve some performance gains that you could hardly
ever achieve by hand-coding.
2.Portable: Application portability is a key
feature in Hibernate it allows developers to port applications to almost all SQL
databases. data query and retrieval is possible with hibernate.
3.Set of objects: Hibernate is set of objects we
don't need to learn SQL ,here we can treat table as object. In case of JDBC we
need to learn SQL .
4.Fast development: Development fast in case of
Hibernate because you don't need to write queries.
5.Get benefit of Cache: Hibernate support two
level of cache. First level and 2nd level. So you can store your data into Cache
for better performance. In case of JDBC you need to implement your java
cache .
ARCHITECTURE OF HIBERNATE
The above diagram shows that Hibernate is using the database and
configure the data to provide persistence services to the application.
Hibernate architecture has three important components.
1.Connection management:-Connection management
efficiently manage the data of data base. Data base connection is the very
expensive part of interacting with the database as it requires a lot of resources
of open and close the database connection.
2.Transaction management:-This management service provide
the ability to the user to execute more than one database statements at a time.
3.Object relational mapping:
Object relational mapping is the
technique of mapping the data from object model to the relational data
model. This part of management is used to insert data ,update data
,select data, and delete the records from the table. In case of connection management and Transaction management
hibernate lacks in performance and capabilities but it is very good tool
as far as object relational mapping is concern.
HOW HIBERNATE WORKS
Hibernate provide tools to generate java classes from the
description file. description files from existing data base and data base tables
from description files.
Hibernate starts from simple java classes (Pojo
= Plain Old Java Objects).
1.To use hibernate you will first create a simple java class.
public class Demo
implements Serializable
{
private int hashValue = 0;
private java.lang.Integer id;
private java.lang.String title;
public Demo()
{
}
public Demo(java.lang.Integer fid)
{
this.setId(fid);
}
public java.lang.Integer getId() {
return id;
}
public void setId(java.lang.Integer id) {
this.id = id;
}
public java.lang.String getTitle() {
return title;
}
public void setTitle(java.lang.String title) {
this.title = title;
}
2.Now we create a mapping file. The mapping file explains Hibernate which
field in the class is mapped to which field of the database.
Mapping is used to insert ,update, select data to the table.
<hibernate-mapping package="r4r">
<class name="Demo" table="Emp">
<id name="id" column="fid" type="java.lang.Integer">
<generator class="sequence">
<param name="sequence">public Demo_fid_seq</param>
</generator>
</id>
<property name="title" column="ftitle" type="java.lang.String" />
</class>
</hibernate-mapping>
3.Asclass is created in hibernate ,now we have
start using the hibernate class. In this case classDemo and we did entry to the data base as:
Demo demo = new Demo();
demo.setTitle("Title");
demo.setTuserFk(tuser);
Transaction tx = session.beginTransaction();
session.save(demo);
tx.commit();
we can use MyEclipse to to create the description file. it provide
functionality to create classes and description file from the data base
directly.
HIBERNATE
Hibernate is a open source that provide a package to work with
relational database. Hibernate is a library called Object Oriented Mapping (ORM)
library. which provide a framework for mapping an object oriented model to
traditional relational database . The main feature of hibernate is mapping
from java classes to database tables and similarly another feature is again
mapping of java data types to the Sql data types Hibernate provide the data
query and retrieval facilities which helps in development and reduce the
development time. Hibernate can be used in java servlets ,swings based
applications and J2EE applications along with EJB.
HQL
HQL is Hibernate Query Language it Sql like query language which
allows to write queries against hibernate's data objects .
If HQL is used in the application then hibernate automatically generate the SQL
query and execute it against the data base.
FEATURES OF HIBERNATE
Hibernate support full object oriented query language.
Hibernate provides a solution to map database tables to a class this is called
mapping.
Object relational mapping is one of the important feature of hibernate.
Hibernate provide a important feature of automatic key generation. i.e.
automatic primary key generation.
Hibernate reduce the development time because it is totally follow the
polymorphism ,inheritance and java collections.
ARCHITECTURE OF HIBERNATE
To work with hibernate it is necessary to first create a java class which
represent the table in a database. The next step is to map the instance variable
in the class with the columns in the database. Now the hibernate is ready to
perform the task on the database like insert, update ,delete etc. the records in
the table. The query is automatically generated by the hibernate to
perform these operations.
Hibernate has many three components
1.Connection management:-This is one of the service of
the hibernate ,it efficiently manage the database connection.
2.Transaction Management:-Another service of hibernate which provide the
ability to the user to execute more than one database statement at a time.
3.Object Relational Mapping:-This is a technique of mapping the data from
an object model to the relational data babe model. This is the part part of
hibernate which is used to update ,insert and delete the records the from the
regarding table.
Hibernate API
Hibernate API is provided in the Java package .org.hibernate
.This package defines the central hibernate APIs
ADVANTAGES OF HIBERNATE
1.It takes less development time.
2.Hibernate is Robust and high in performance.
3.Hibernate is free under the LPGL lisence. so it can be used for develop
application and distribute free.
4.Hibernate is database independent. it can be used for any database.
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Username :sunil
Comments :Problem with multiple update....
How to execute the update query for multiple columns in hql
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