#ManagedProperty in a Spring managed bean is null - spring

Question

I've some trouble with injecting one managedbean in another by defining a managedproperty. I'm googling and stackoverflowing now for 3 days, but with no result...
I'm developing with eclipse 4.2 and deploying to an integrated Tomcat 7
So, can anybody tell me, why my property is null?
pom.xml
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<spring.version>3.0.5.RELEASE</spring.version>
<java.version>1.6</java.version>
</properties>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-web</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-expression</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-orm</artifactId>
<version>${spring.version}</version>
<type>jar</type>
<scope>compile</scope>
</dependency>
web.xml
<web-app version="3.0" 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/web-app_3_0.xsd">
<context-param>
<param-name>contextConfigLocation</param-name>
<param-value>/WEB-INF/applicationContext*.xml</param-value>
</context-param>
<listener>
<listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
</listener>
I have set the beans in applicationContext for scanning #Autowired annotation. (Yes, i tried it without beans in applicationContext, but ManagedProperty will not be set, too.)
applicationContext.xml
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:context="http://www.springframework.org/schema/context"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:tx="http://www.springframework.org/schema/tx"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx.xsd
http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.0.xsd">
<context:annotation-config />
<context:component-scan base-package="myPackage" />
<bean class="org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor"/>
<bean class="myPackage.dao.UserDao" id="userDao" />
<bean class="myPackage.dao.WorldDao" id="worldDao" />
<bean class="myPackage.dao.BuildingTypeDao" id="buildingTypeDao" />
<bean class="myPackage.dao.BuffTypeDao" id="buffTypeDao" />
<bean class="myPackage.dao.ClanDao" id="clanDao" />
<bean class="myPackage.bean.MainBean" id="mainBean" />
<bean class="myPackage.bean.UserBean" id="userBean" />
<bean class="myPackage.bean.AdminBean" id="adminBean" />
MainBean
package myPackage.bean;
import java.io.Serializable;
import javax.faces.bean.ManagedBean;
import javax.faces.bean.SessionScoped;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import myPackage.model.MainModel;
#ManagedBean
#SessionScoped
public class MainBean implements Serializable {
private static final long serialVersionUID = 1L;
private static final Logger logger = LoggerFactory.getLogger(MainBean.class);
private MainModel model;
/**
* #return the model
*/
public MainModel getModel() {
if (model == null) {
model = new MainModel();
}
return model;
}
/**
* #param model the model to set
*/
public void setModel(MainModel model) {
this.model = model;
}
}
UserBean
package myPackage.bean;
import java.io.Serializable;
import javax.faces.application.FacesMessage;
import javax.faces.bean.ManagedBean;
import javax.faces.bean.ManagedProperty;
import javax.faces.bean.RequestScoped;
import javax.faces.context.FacesContext;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import myPackage.dao.UserDao;
import myPackage.entity.User;
#ManagedBean
#RequestScoped
public class UserBean implements Serializable {
private static final long serialVersionUID = 1L;
private static final Logger logger = LoggerFactory.getLogger(UserBean.class);
#ManagedProperty(value="#{mainBean}")
private MainBean mainBean;
#Autowired
private UserDao userDao;
/**
* #return the mainBean
*/
public MainBean getMainBean() {
return mainBean;
}
/**
* #param mainBean the mainBean to set
*/
public void setMainBean(MainBean mainBean) {
this.mainBean = mainBean;
}
public String doLogin() {
User user = userDao.getUserByUsernameAndPassword(getMainBean().getModel().getUser().getUsername(), getMainBean().getModel().getUser().getPassword());
if (user != null) {
getMainBean().getModel().setUser(user);
logger.info("User '"+getMainBean().getModel().getUser().getUsername()+"' logged in");
getMainBean().getModel().setSelectedTab(0);
} else {
FacesContext.getCurrentInstance().addMessage(null, new FacesMessage(FacesMessage.SEVERITY_ERROR,"Login failed", "Username and/or password wrong!"));
logger.warn("User '"+getMainBean().getModel().getUser().getUsername()+"' login failed");
}
return null;
}
UserDao
package myPackage.dao;
import java.util.List;
import javax.persistence.EntityManager;
import javax.persistence.PersistenceContext;
import javax.persistence.Query;
import org.springframework.stereotype.Repository;
import org.springframework.transaction.annotation.Transactional;
import myPackage.entity.User;
#Repository
public class UserDao {
#PersistenceContext
private EntityManager entityManager;
#Transactional
public void save(User user) {
if (user.getId() == null) {
entityManager.persist(user);
} else {
entityManager.merge(user);
}
}
#SuppressWarnings("unchecked")
public List<User> list() {
return entityManager.createQuery("select u from User u")
.getResultList();
}
public User getUserByUsername(String username) {
try {
Query q = entityManager.createQuery("select u from User u where u.username = :username");
q.setParameter("username", username);
User u = (User) q.getSingleResult();
return u;
} catch (Exception e) {
return null;
}
}
public User getUserByUsernameAndPassword(String username, String password) {
try {
Query q = entityManager.createQuery("select u from User u where u.username = :username and u.password = :password");
q.setParameter("username", username);
q.setParameter("password", password);
User u = (User) q.getSingleResult();
return u;
} catch (Exception e) {
return null;
}
}
#Transactional
public User getUserById(Long id) {
return entityManager.find(User.class, id);
}
#Transactional
public void delete(User user) {
entityManager.remove(user);
}
public void deleteById(Long id) {
delete(getUserById(id));
}
}
And now the Exception...
Caused by: java.lang.NullPointerException
at myPackage.bean.UserBean.doLogin(UserBean.java:47)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
Line 47:
User user = userDao.getUserByUsernameAndPassword(getMainBean().getModel().getUser().getUsername(), getMainBean().getModel().getUser().getPassword());
Debugging shows that getMainBean() returns null.
I'm open for suggests to improve my concept!

Answer 1

Your JSF backing beans (MainBean and UserBean) should be managed either by JSF or by Spring, but not by both of them.
If your beans are managed by JSF:
You annotate them with #ManagedBean and #...Scoped
You don't need to declare them in applicationContext.xml
You use #ManagedProperty instead of #Autowired, even if you need to inject beans managed by Spring (don't forget setters, #ManagedProperty requires it):
#ManagedProperty("#{userDao}")
private UserDao userDao;
If your beans are managed by Spring:
You declare them in applicationContext.xml with appropriate scopes (view scope is not supported)
You don't need #ManagedBean and #...Scoped
You use #Autowired instead of #ManagedProperty and you cannot inject beans managed by JSF this way
In both cases you need to configure Spring-JSF bridge in faces-context.xml:
<application>
<el-resolver>
org.springframework.web.jsf.el.SpringBeanFacesELResolver
</el-resolver>
</application>