Java Reference
In-Depth Information
As we saw in the previous chapter, the Data Access Object (
DAO
) pattern can be
used to hide the unique implementation peculiarities of data-related
API
s to pro-
vide a simple and common
API
for application developers. This pattern is very
powerful, and is not unique to i
BATIS
, as other projects have created
DAO
imple-
mentations that you can use with i
BATIS
.
In this chapter, we look at a couple more
SQL
-based
DAO
implementations, as
well as a couple of
DAO
implementations for other data sources (
LDAP
and web
services). Then we explore the other options for
DAO
layers, including the Spring
framework's excellent
DAO
implementation. We also consider the implications of
creating your own custom
DAO
layer.
11.1 Non-SQLMap DAO implementations
In the last chapter, we defined an interface for a
DAO
, and then built a
SQL
Map-based implementation of it. In the next two sections, we implement that
interface again with both Hibernate and
JDBC
to show you how the
DAO
pat-
tern can make it easier to use different database access technologies with i
BATIS
in your application.
11.1.1
A Hibernate DAO implementation
The Hibernate
DAO
implementation is very different from the
SQL
Map version,
but because of the
DAO
interface, it is used in exactly the same manner as far as
the application code that uses it is concerned.
Defining the DAO context
Listing 11.1 shows the
XML
fragment that we need in the
Dao.xml
file to describe
the
DAO
context that will use Hibernate.
Listing 11.1
XML fragment defining a DAO context using Hibernate
<context id="hibernate">
<transactionManager type="HIBERNATE">
<property name="hibernate.connection.driver_class"
value="org.postgresql.Driver" />
<property name="hibernate.connection.url"
value="jdbc:postgresql:ibatisdemo" />
<property name="hibernate.connection.username"
value="ibatis" />
<property name="hibernate.connection.password"
value="ibatis" />
<property name="hibernate.connection.pool_size"
value="5" />
