CDI

CDI (JSR-299) is an emerging standard for contexts and dependency injection for Java EE.

Here we discuss how to use CDI with ZK, especially the use of DelegatingVariableResolver. It provides the basic support of CDI which allow a ZUML document to access variables defined in CDI. For more comprehensive support, please refer to another product: ZK CDI.

For more information, please refer to the following blogs:

• Integrate ZK and JSR-299
• Handling ZK Events using CDI event notification model

Example

Here is a Hello World example. Suppose we have a Java class called HelloWorld as shown below.

@Named
@SessionScoped
public class HelloWorld implements Serializable {
    private final String text = "Hello World";
    public String getText() {
        return text;
    }
}

Then, we could access it by specifying the variable resolver: DelegatingVariableResolver as shown below:

<?variable-resolver class="org.zkoss.zkplus.cdi.DelegatingVariableResolver"?>
<window title="ZK + CDI: Hello World" width="300px">
    My weld-injected bean says: ${helloWorld.text}
</window>

DelegatingVariableResolver resolves all variables defined by CDI (with Java annotations). In other words, it makes them visible to the ZUML document, including EL expressions, data binding and zscript.

Setup Tomcat + Weld

Weld is an implementation of CDI. Here is a brief installation instructions:

• Copy weld-servlet.jar to your application's WEB-INF/lib folder. You can find the jar file in [Weld 1.0 SP1.

• Add in your application's WEB-INF/web.xml the following listener. This makes Weld bind with Tomcat.

<listener>
    <listener-class>org.jboss.weld.environment.servlet.Listener</listener-class>
</listener>

• In your application's META-INF folder, creates a context.xml file with following contents. This provides a JNDI reference java:comp/env/BeanManager for the accessing to the Weld bean manager. The ZK CDI variable resolver will need this.

<Context>
    <Resource name="BeanManager" auth="Container"
        type="javax.enterprise.inject.spi.BeanManager"
        factory="org.jboss.weld.resources.ManagerObjectFactory"/>
</Context>

• Add WEB-INF/beans.xml with empty content to the web root.