Hibernate jj

 Hibernate is a free, open source Java package that
makes it easy to work with relational databases.

 Hibernate makes it seem as if your database
contains plain Java objects like you use every day,
without having to worry about how to get them out
of (or back into) mysterious database tables.

 Hibernate liberates you to focus on the objects and
features of your application, without having to
worry about how to store them or find them later.

 Cost effective.

 Learning is very easy compare to EJB.

 High Performance than EJB

 No more need for JDBC API for Result set handling.

 Switching to other SQL database requires few
changes in Hibernate configuration file

 Database independent application

 Avoid writing queries

 Avoid JDBC API completely

 Hibernate uses connection pooling technique

 Automatic Key Generation

 Develop the Application in short Period of time

 DB2
 MySQL
 PostgreSQL
 Oracle (any version)
 Microsoft SQL Server
 HypersonicSQL
 Informix
 Ingres
 Interbase
 Pointbase
 Mckoi SQL
 Progress
 FrontBase
 SAP DB
 Sybase

 Hibernate architecture has three main components:
 Connection Management
Hibernate Connection management service provide efficient
management of the database connections. Database connection is
the most expensive part of interacting with the database as it
requires a lot of resources of open and close the database
connection.

 Transaction management:
Transaction management service provide the ability to the user
to execute more than one database statements at a time.

 Object relational mapping:
Object relational mapping is technique of mapping the data
representation from an object model to a relational data model. This
part of the hibernate is used to select, insert, update and delete the
records form the underlying table. When we pass an object to a
Session.save() method, Hibernate reads the state of the variables
of that object and executes the necessary query.

 Hibernate is very good tool as far as object
relational mapping is concern but in terms
of
◦ connection management and
◦ transaction management,
it is lacking in performance and capabilities. So
usually hibernate is being used with other
connection management and transaction
management tools. For example apache DBCP is
used for connection pooling with the Hibernate.

 Hibernate 3.0 provides three full-featured
query facilities:
 Hibernate Query Language
 Hibernate Criteria Query API
 Hibernate Native Query

 The Criteria interface allows to create and
execute object-oriented queries. It is
powerful alternative to the HQL but has own
limitations. Criteria Query is used mostly in
case of multi criteria search screens, where
HQL is not very effective.

 Native SQL is handwritten SQL for all
database operations like create, update,
delete and select. Hibernate Native Query
also supports stored procedures. Hibernate
allows you to run Native SQL Query for all the
database operations, so you can use your
existing handwritten sql with Hibernate, this
also helps you in migrating your SQL/JDBC
based application to Hibernate.

 Configuring Hibernate

 Persistence Class

 Map the Object to the Database table (Using
Annotation)

 Setting up the Database
 Insert, Update and Delete records in the table (Hibernate
automatically creates query to perform this operations)

Make SQL be object oriented
•Classes and properties instead of tables and columns
•Polymorphism
•Associations
•Much less verbose than SQL
Full support for relational operations
•Inner/outer/full joins, cartesian products
•Projection
•Aggregation (max, avg) and grouping
•Ordering
•Subqueries
•SQL function calls

Simplest HQL Query:

from AuctionItem

i.e. get all the AuctionItems:

List allAuctions = session.createQuery(“from AuctionItem”).list();
•SQL function calls

1. HQL Select Query Example

Retrieve a stock data where stock code is “7277″.

Query query = session.createQuery("from Stock where stockCode = :code ");
query.setParameter("code", "7277");
List list = query.list();

Query query = session.createQuery("from Stock where stockCode = '7277' ");
List list = query.list();

2. HQL Update Query Example

Update a stock name to “DIALOG1″ where stock code is “7277″

Query query = session.createQuery("update Stock set stockName =
:stockName" + " where stockCode = :stockCode");
query.setParameter("stockName", "DIALOG1");
query.setParameter("stockCode", "7277");
int result = query.executeUpdate();

Query query = session.createQuery("update Stock set stockName =
'DIALOG1'" + " where stockCode = '7277'");

3. HQL Delete Query Example

Delete a stock where stock code is “7277″.

Query query = session.createQuery("delete Stock where stockCode =
:stockCode");
query.setParameter("stockCode", "7277");

Query query = session.createQuery("delete Stock where stockCode = '7277'");

4. HQL Insert Query Example

In HQL, only the INSERT INTO … SELECT … is supported; there is no INSERT INTO … VALUES. HQL
only support insert from another table. For example

Insert a stock record from another backup_stock table. This can also called
bulk-insert statement.

Query query = session.createQuery("insert into Stock(stock_code,
stock_name)" + "select stock_code, stock_name from backup_stock");

Note :The query.executeUpdate() will return how many number of record has
been inserted, updated or deleted.

Like other operations, transactions are performed using the Session object.
Here’s an example:

Session session = sf.openSession();
Transaction tx = session.beginTransaction();

try {
AuctionItem item =
(AuctionItem) session.get(ActionItem.class, itemId);
bid.setItem(item);
item.getBids().add(bid);
tx.commit();
} catch (Exception e) {
tx.rollback();
throw e;
} finally {
session.close();
}

Performance of Hibernate web applications is improved using caching by
optimizing the database applications.

The cache actually stores the data already loaded from the database, so that the
traffic between our application and the database will be reduced when the
application want to access that data again. Maximum the application will works
with the data in the cache only. Whenever some another data is needed, the
database will be accessed. Because the time needed to access the database is
more when compared with the time needed to access the cache. So obviously the
access time and traffic will be reduced between the application and the database.
Here the cache stores only the data related to current running application. In order
to do that, the cache must be cleared time to time whenever the applications are
changing.

1.Introduction.
•First-level cache.
•Second-level cache.
2.Cache Implementations.
•EHCache.
•OSCache.
•SwarmCache.
•JBoss TreeCache.
3.Caching Stringategies.
•Read-only.
•Read-Write.
•Nonstriict read-write.
•Transactional.
4.Configuration.
5.<cache> element.
6.Caching the queries.

First-level cache.

First-level cache always Associates with the Session object. Hibernate uses
this cache by default. Here, it processes one transaction after another one,
means wont process one transaction many times. Mainly it reduces the
number of SQL queries it needs to generate within a given transaction. That is
instead of updating after every modification done in the transaction, it updates
the transaction only at the end of the transaction.

Second-level cache

Second-level cache always associates with the Session Factory object.
While running the transactions, in between it loads the objects at the Session
Factory level, so that those objects will available to the entire application,
don’t bounds to single user. Since the objects are already loaded in the
cache, whenever an object is returned by the query, at that time no need to go
for a database transaction. In this way the second level cache works. Here we
can use query level cache also. Later we will discuss about it.

Cache Implementations

Hibernate supports four open-source cache implementations named
EHCache (Easy Hibernate Cache), OSCache (Open Symphony Cache),
Swarm Cache, and JBoss Tree Cache. Each cache has different
performance, memory use, and configuration possibilities. .

EHCache (Easy Hibernate Cache)
(org.hibernate.cache.EhCacheProvider)

• It is fast.
• lightweight.
• Easy-to-use.
• Supports read-only and read/write caching.
• Supports memory-based and disk-based caching.
• Does not support clustering.

OSCache (Open Symphony Cache)
(org.hibernate.cache.OSCacheProvider)

• It is a powerful .
• flexible package
• supports read-only and read/write caching.
• Supports memory- based and disk-based caching.
• Provides basic support for clustering via either JavaGroups or JMS

SwarmCache (org.hibernate.cache.SwarmCacheProvider)

• is a cluster-based caching.
• supports read-only or nonstrict read/write caching .
• appropriate for applications those have more read operations than write
operations.

Boss TreeCache (org.hibernate.cache.TreeCacheProvider)

• is a powerful replicated and transactional cache.
• useful when we need a true transaction-capable caching architecture .

Hibernate jj

More Related Content

What's hot (20)

Viewers also liked (18)

Similar to Hibernate jj (20)

Recently uploaded (20)

Hibernate jj

Editor's Notes