如何在ManagedBean中注入CDI Bean？

Question

I want to inject a CDI Bean in a ManagedBean either with the annotation @Inject or @Produce. The CDI Bean which I use is:

@Named
@Startup
@ApplicationScoped
public class BaseBean {

private List<String> custs;

public List<String> getCusts() {
    return custs;
}

public void setCusts(List<String> emps) {
    this.custs = emps;
}

public BaseBean(){

}

@PostConstruct
void init() {
    custs = new ArrayList<String>();
    custs.add("Cust1");
    custs.add("Cust3");
    custs.add("Cust2");
    custs.add("Cust4");
}

}

The ManagedBean, in which I want to inject the CDI Bean is:

@SessionScoped
@ManagedBean
public class Hello implements Serializable {

@Inject
private BaseBean dBean;

private static final long serialVersionUID = 1L;
private List<String> customers;
private List<String> customersSelect;

public Hello() {
}

@PostConstruct
void init() {
//  dBean = new BaseBean();
    customers = dBean.getCusts();
}

public List<String> getCustomers() {
    return customers;
}

public List<String> getCustomersSelect() {
    return customersSelect;
}

public void setCustomersSelect(List<String> customersSelect) {
    this.customersSelect = customersSelect;
}
}

In the init function however, it throws NullPointerException. If I use the annotation @Produces instead of @Inject, the result is the same: NullPointerException. Is anything wrong with the CDI Bean (improper annotations)? Do I try to inject it with a wrong way? Does my code lack of something? How can I get it work? Here is the JSF code:

<h:form id ="f">
    <h:selectManyCheckbox layout="pageDirection" border="1"  value="#{hello.customersSelect}">
        <f:selectItems value="#{hello.customers}"></f:selectItems>
    </h:selectManyCheckbox><br />
    <h:commandButton action="response.xhtml" value="Click me" />
</h:form>

PS: If I use a Stateless Bean as BaseBean and I inject it with the annotation @EJB, it works with no problem.

UPDATE: I have tried it with the annotations @SessionScoped ( javax.enterprise.context.SessionScoped ) and @Named on the Hello class. Although I do not receive a NullPointerException , the h:selectManyCheckbox is empty. moreover, it strikes me, that when I add the beans.xml file under META-INF folder, I receive a StartException , although the file is there supposed to be. I think my application lacks the proper configuration to be capable of Dependency Injection. What is likely to need additional configuration?

UPDATE 2: This error appears when I add the beans.xml file in the WEB-INF folder. The beans.xml file is empty, it contains only the line :

<?xml version="1.0" encoding="UTF-8"?> 

The error is:

Services which failed to start:      service jboss.deployment.unit."JSF1.war".PARSE: org.jboss.msc.service.StartException in service jboss.deployment.unit."JSF1.war".PARSE: Failed to process phase PARSE of deployment "JSF1.war"

12:51:11,482 ERROR [org.jboss.as.server.deployment.scanner] (DeploymentScanner-threads - 1) {"JBAS014653: Composite operation failed and was rolled back. Steps that failed:" => {"Operation step-2" => {"JBAS014671: Failed services" => {"jboss.deployment.unit.\"JSF1.war\".PARSE" => "org.jboss.msc.service.StartException in service jboss.deployment.unit.\"JSF1.war\".PARSE: Failed to process phase PARSE of deployment \"JSF1.war\""}}}}

Answer 1

What @patlov is suggesting will work if you use @Named on your CDI beans. However, if you're working in an environment that supports CDI, do not use @ManagedBean . Instead, use CDI all the way. See this answer and I'm sure you could find numerous other ones that strongly advise against what you're trying to do.

Just switch from javax.faces.bean.SessionScoped to javax.enterprise.context.SessionScoped and everything will magically work. What you may run into is the absense of @ViewScoped from CDI however, in which case use something like JBoss Seam or Apache Deltaspike that implement it for you. As an added benefit, they will also automatically replace all of the JSF scopes with CDI scopes automatically if you already have existing code written for JSF.

Update: This should be the content of your beans.xml:

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/beans_1_0.xsd">
</beans>

Answer 2

通过在应用程序中放置WEB-INF/beans.xml文件，确保已启用CDI。

Answer 3

If you are using @ManagedBean use @ManagedProperty to inject properties:

@ManagedProperty(value = "#{baseBean}")
private BaseBean dBean;

// getter and setter