Table of Contents
The best way to learn the Microcontainer is through examples. The Microcontainer distribution is bundled
with several examples, which we will discuss in later this guide. In this section, let us first have a look at
the
simple
example. It shows the structure of a simple Microcontainer application and how to run the application in both
standalone and JBoss AS environments.
The
simple
example is located in the
examples/simple
directory of the Microcontainer distribution. It contains a single class under the
src/main
directory.
public class SimpleBean { public SimpleBean() { System.out.println("SimpleBean() constructor"); } }
The
SimpleBean
object prints to the system console when it is instantiated via the default constructor. Now, we need to use
the Microcontainer to instantiate a
SimpleBean
POJO. We do this by invoking the Microcontainer with the
src/resources/META-INF/jboss-beans.xml
configuration file.
<deployment xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="urn:jboss:bean-deployer bean-deployer_2_0.xsd" xmlns="urn:jboss:bean-deployer:2.0"> <bean name="Simple" class="org.jboss.example.microcontainer.simple.SimpleBean"/> </deployment>
This configuration file tells the Microcontainer to create an instance of the
SimpleBean
POJO and manage it under the name
Simple
. When other objects in the application need to access this
SimpleBean
instance, they can simply ask the Microcontainer API for the
Simple
object. Essentially, we just created a
SimpleBean
singleton instance here. When we run this application, we are expected to see the
"SimpleBean() constructor"
printout on the console when the Microcontainer creates the
Simple
object.