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| Spring Framework |
Spring Core with Data Access Framework
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In this article, we will move on to the
main process of any enterprise application:
Data Persistence. For this we have to
initialize our data access framework,
manage resources, handle various
exceptions and if anything goes wrong, we
must roll-back so as to save the existing
data.
Spring comes with a family of data access
frameworks that integrates well will variety
of data access technologies like JDBC, Java
Data Objects and Object Relational
Mapping (ORM) tools like Hibernate, OJB,
iBatis etc.,
Many JEE application servers and even web
servers provide a ‘dataSource’ via JNDI
name. To configure the spring bean with
the JNDI name of our ‘dataSource’ and use
its connection pooling facility, ‘JndiObjectFactoryBean’ is used. When
a DataSource is not present, we need a
connection pooling bean that implements ‘dataSource’. For this purpose we use dbcp.BasicDataSource’. By using this
we can have a ‘dataSource’ with
connection pooling independent of
application server.
To perform unit-tests in our data access
code, spring comes with a very lightweight ‘dataSource’ implementation class: ‘DriverManagerDataSource’. This class
can be easily configured for unit tests as
shown:
…
…
DriverManagerDataSource dataSource =
new DriverManagerDataSource();
dataSource.setDriverClassName(driver);
dataSource.setUrl(url);
dataSource.setUsername(username);
dataSource.setPassword(password);
… |
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These properties can be configured in the
spring configuration file also.
Spring’s own Data Access Framework
Spring comes with its own data access
framework. Spring separates the fixed and
variant parts of data access process into
two distinct classes: template and
callback. Template manages the fixed part
of our framework like data connection,
managing resources, controlling
transaction etc., while the Callback defines
the things that are specific to our
application like creating statements,
binding parameters etc.,
The template class of Spring is ‘JdbcTemplate’. A ‘dataSource’ is
provided inside JdbcTemplate.
An example of database connection
using ‘JdbcTemplate’ is shown below.
Here we are using ‘MySql’ database.
The MySql database can be downloaded
from http://www.mysql.com.
Download latest MySql version and
mysql-connector-java-3.1.6-bin.jar.
Install them in the hard disk.
Installing MySql:
1. For Mysql give a username(‘root’) and a
password (‘root’).
2. Then start the ‘My Sql Console Line Client’ from programs and type the
password. The prompt will be changed
to mysql,mysql> show databases; Few
databases will be present by default like
mysql and test. Let’s use ‘test’ for our
purpose.mysql> use test;
3. We will get a message as ‘Database
changed’.
4. Next create a table in ‘test’ database as
follows
mysql> create table table1(name text,
place text); |
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Sept 2007 | Java Jazz Up | 55 |
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