Contexts and Dependency Injection is new API introduce by Oracle . CDI is a standard way to provide dependency injection in java application .
CDI (JSR-299): Contexts and Dependency Injection for the Java EE platform was finalized in December 2009. CDI 1.1 is due to be released in the first half of 2013 to coincide with the release of Java EE 7.
JBOSS Weld is a stranded implementation of CDI API .
We will take simple example with JSF application .
Following jar file required for JSF-CDI Application
for JSF
javax.el-api-3.0.0.jar
javax.faces-2.2.8-02.jar
javax.faces-api-2.2.jar
javax.interceptor-api-1.2.jar
for CDI
weld-servlet-2.2.6.Final.jar
javax.inject-1.jar
cdi-api-1.2.jar
following file required for this application
index.xhtml
web.xml
beans.xml
context.xml
faces-config.xml
Message.java
MessageImpl.java
MessageBean.java
first of all create Message interface
Message.java
public interface Message {
public void showMessage();
}
MessageImpl.java
package in.jk.cdi;
public class MessageImpl implements Message {
@Override
public void showMessage() {
System.out.println("Welcome in the World of CDI with JSF and JBOSS Weld and Tomcat 8");
}
}
MessageBean.java
package in.jk.cdi;
import javax.enterprise.context.RequestScoped;
import javax.inject.Inject;
import javax.inject.Named;
@Named("jk")
@RequestScoped
public class MessageBean{
@Inject Message message;
public void showMessage(){
System.out.println("Context and Dependency Injection ");
message.showMessage();
}
}
index.xhtml
<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml"
xmlns:h="http://xmlns.jcp.org/jsf/html">
<h:head>
<title>Title</title>
</h:head>
<h:body>
<h:form>
<h:commandButton value="Get Messgae " action="#{jk.showMessage}"></h:commandButton>
</h:form>
</h:body>
</html>
Put the following context.xml file in META_INF folder of application
context.xml
<?xml version="1.0" encoding="UTF-8"?>
<Context antiJARLocking="true" path="/tomcat-test">
<Resource
name="BeanManager"
auth="Container"
type="javax.enterprise.inject.spi.BeanManager"
factory="org.jboss.weld.resources.ManagerObjectFactory"
/>
</Context>
Put the following three file xml file in WEB_INF folder of application
beans.xml
<?xml version="1.0" encoding="UTF-8"?>
<beans
xmlns="http://xmlns.jcp.org/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/beans_1_1.xsd"
bean-discovery-mode="all">
</beans>
faces-config.xml
<?xml version="1.0" encoding="UTF-8"?>
<faces-config xmlns="http://xmlns.jcp.org/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-facesconfig_2_2.xsd"
version="2.2">
</faces-config>
web.xml
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" id="WebApp_ID" version="3.0">
<display-name>efiling</display-name>
<welcome-file-list>
<welcome-file>faces/index.xhtml</welcome-file>
</welcome-file-list>
<servlet>
<servlet-name>Faces Servlet</servlet-name>
<servlet-class>javax.faces.webapp.FacesServlet</servlet-class>
<load-on-startup>1</load-on-startup>
</servlet>
<servlet-mapping>
<servlet-name>Faces Servlet</servlet-name>
<url-pattern>/faces/*</url-pattern>
</servlet-mapping>
<session-config>
<session-timeout>30</session-timeout>
</session-config>
<!-- This enrty require in web.xml to register CDI Dependency Manager -->
<resource-env-ref>
<!-- Enable Weld CDI, also needs META-INF/context.xml entry -->
<resource-env-ref-name>BeanManager</resource-env-ref-name>
<resource-env-ref-type>javax.enterprise.inject.spi.BeanManager</resource-env-ref-type>
</resource-env-ref>
</web-app>
Output is at Console ,...
Context and Dependency Injection
Welcome in the World of CDI with JSF and JBOSS Weld and Tomcat 8
