Author: Ievgen Shulga
Level: Intermediate
Technologies: CDI, JSF
Summary: The cdi-decorator
quickstart demonstrates the use of a CDI Decorator to intercept bean methods and modify the business logic.
Target Product: WildFly
Source: https://github.com/wildfly/quickstart/
The cdi-decorator
quickstart demonstrates the use of CDI decorators in WildFly Application Server. A decorator implements one or more bean types and intercepts business method invocations of beans which implement those bean types. These bean types are called decorated types.
Decorators are similar to interceptors, but because they directly implement operations with business semantics, they are able to implement business logic and, conversely, unable to implement the cross-cutting concerns for which interceptors are optimized.
Decorators may be associated with any managed bean that is not itself an interceptor or decorator or with any EJB session bean. A decorator instance is a dependent object of the object it decorates.
This example represents a common decorator design pattern. We take a class and we wrap decorator class around it. When we call the class, we always pass through the surrounding decorator class before we reach the inner class. In this example, the decorator class simply changes the staff bonus from 100
to 200
and the staff position from Java Developer
to Team Lead
. It then logs a message to the server console.
By default, all decorators are disabled, so the application will run without using decorator. We need to enable our decorator in the WEB-INF/beans.xml
descriptor to make it work.
The application this project produces is designed to be run on WildFly Application Server 11 or later.
All you need to build this project is Java 8.0 (Java SDK 1.8) or later and Maven 3.3.1 or later. See Configure Maven for WildFly 11 to make sure you are configured correctly for testing the quickstarts.
In the following instructions, replace WILDFLY_HOME
with the actual path to your WildFly installation. The installation path is described in detail here: Use of WILDFLY_HOME and JBOSS_HOME Variables.
For Linux: WILDFLY_HOME/bin/standalone.sh
For Windows: WILDFLY_HOME\bin\standalone.bat
mvn clean install wildfly:deploy
This will deploy target/cdi-decorator.war
to the running instance of the server.
The application will be running at the following URL: http://localhost:8080/cdi-decorator.
You can specify decorator of the bean in the WEB-INF/beans.xml
file by doing one of the following:
For this example, uncomment the <decorators>
tag in the WEB-INF/beans.xml
file and redeploy the application. When you access the application, you will see changed information from web-browser and following in the server log:
CDI decorator method was called!
CDI decorator method was called!
The message appears twice because the decorator is called twice, once to get the staff position and then again to get the staff bonus.
In order to switch back to the default implementation, comment the decorators
block in the WEB-INF/beans.xml
file and redeploy the quickstart.
mvn wildfly:undeploy
You can also start the server and deploy the quickstarts or run the Arquillian tests from Eclipse using JBoss tools. For general information about how to import a quickstart, add a WildFly server, and build and deploy a quickstart, see Use JBoss Developer Studio or Eclipse to Run the Quickstarts.
If you want to debug the source code of any library in the project, run the following command to pull the source into your local repository. The IDE should then detect it.
mvn dependency:sources