Java Reference
In-Depth Information
Instead, i
BATIS
uses a pool of connections that are kept open and shared by all
users of the application.
Many vendors provide pooled versions of their drivers, but one problem is that
the features and configuration of the pools are as varied as the implementations.
The Jakarta Commons Database Connection Pool (
DBCP
) project is a wrapper
that makes it possible to easily use any
JDBC
driver as part of a connection pool.
3.3.3
Distributed caching
Caching data in a multiuser environment can be tricky. Caching data in a multi-
server environment makes the multiuser environment look simple.
To deal with this problem, i
BATIS
provides an implementation of caching that
uses the OpenSymphony cache (
OSC
ache).
OSC
ache can be configured to cluster
across multiple servers to provide scalability and fail-over support.
Now that we've looked at some of the features you can configure in i
BATIS
,
let's add it to your application!
3.4 Adding iBATIS to your application
Once you've configured i
BATIS
, the only change required to make it available to
your application is to add it (and any other dependencies you choose) to your
compile-time and runtime classpaths. Let's start with a look at the classpath.
Every computer system needs a way to find what it needs to work. Just like the
$PATH
variable on Linux or
%PATH%
variable on Windows, Java has a path that it
uses to find its required components that is called the
classpath
.
In the early days of Java, you would set a
CLASSPATH
environment variable.
While this still works, it is messy because it is inherited by every Java application on
the system.
The Java Runtime Environment (
JRE
) also has a special
lib/ext
directory that
can be used, but this is not recommended except for a few special cases because
all classes in this directory are shared by all applications that use the
JRE
. We rec-
ommend that you don't put i
BATIS
in that directory.
So how do you make i
BATIS
available to your application? There are a couple
of ways.
3.4.1
Using iBATIS with a stand-alone application
For a stand-alone application, you can set the classpath in a startup script. This is
a reasonable approach used by many applications. For example, if you have a
stand-alone application that is console based, you would add the i
BATIS
JAR
s to
the classpath in Linux using the
-cp
switch, like this:
