Hibernate using Query via Spring injection

Beginner here to hibernate, spring. Followed tutorial here to setup hibernae + spring + struts2 project: http://splinter.com.au/blog/?p=224

I wanted to prepare queries. So I tried following: Services.java

public class Services {
  protected SessionFactory sessionFactory;
  public void setSessionFactory(SessionFactory value) {
    sessionFactory = value;
  }

  protected Session sess() {
    return sessionFactory.getCurrentSession();
  }

  private Query query = sess().createQuery("....");
}

Following exception is thrown as session is not injected, how can I fix it?

org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'services' defined in ServletContext resource [/WEB-INF/applicationContext.xml]: Instantiation of bean failed; nested exception is org.springframework.beans.BeanInstantiationException: Could not instantiate bean class [com.dao.Services]: Constructor threw exception; nested exception is java.lang.NullPointerException
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateBean(AbstractAutowireCapableBeanFactory.java:955)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:901)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:485)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:456)
    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:291)
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222)
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:288)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:190)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:574)
    at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:895)
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:425)
    at org.springframework.web.context.ContextLoader.createWebApplicationContext(ContextLoader.java:276)
    at org.springframework.web.context.ContextLoader.initWebApplicationContext(ContextLoader.java:197)
    at org.springframework.web.context.ContextLoaderListener.contextInitialized(ContextLoaderListener.java:47)
    at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:3910)
    at org.apache.catalina.core.StandardContext.start(StandardContext.java:4393)
    at org.jboss.web.tomcat.service.deployers.TomcatDeployment.performDeployInternal(TomcatDeployment.java:310)
    at org.jboss.web.tomcat.service.deployers.TomcatDeployment.performDeploy(TomcatDeployment.java:142)
    at org.jboss.web.deployers.AbstractWarDeployment.start(AbstractWarDeployment.java:461)
    at org.jboss.web.deployers.WebModule.startModule(WebModule.java:118)
    at org.jboss.web.deployers.WebModule.start(WebModule.java:97)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
    at java.lang.reflect.Method.invoke(Unknown Source)
    at org.jboss.mx.interceptor.ReflectedDispatcher.invoke(ReflectedDispatcher.java:157)
    at org.jboss.mx.server.Invocation.dispatch(Invocation.java:96)
    at org.jboss.mx.server.Invocation.invoke(Invocation.java:88)
    at org.jboss.mx.server.AbstractMBeanInvoker.invoke(AbstractMBeanInvoker.java:264)
    at org.jboss.mx.server.MBeanServerImpl.invoke(MBeanServerImpl.java:668)
    at org.jboss.system.microcontainer.ServiceProxy.invoke(ServiceProxy.java:206)
    at $Proxy38.start(Unknown Source)
    at org.jboss.system.microcontainer.StartStopLifecycleAction.installAction(StartStopLifecycleAction.java:42)
    at org.jboss.system.microcontainer.StartStopLifecycleAction.installAction(StartStopLifecycleAction.java:37)
    at org.jboss.dependency.plugins.action.SimpleControllerContextAction.simpleInstallAction(SimpleControllerContextAction.java:62)
    at org.jboss.dependency.plugins.action.AccessControllerContextAction.install(AccessControllerContextAction.java:71)
    at org.jboss.dependency.plugins.AbstractControllerContextActions.install(AbstractControllerContextActions.java:51)
    at org.jboss.dependency.plugins.AbstractControllerContext.install(AbstractControllerContext.java:348)
    at org.jboss.system.microcontainer.ServiceControllerContext.install(ServiceControllerContext.java:297)
    at org.jboss.dependency.plugins.AbstractController.install(AbstractController.java:1633)
    at org.jboss.dependency.plugins.AbstractController.incrementState(AbstractController.java:935)
    at org.jboss.dependency.plugins.AbstractController.resolveContexts(AbstractController.java:1083)
    at org.jboss.dependency.plugins.AbstractController.resolveContexts(AbstractController.java:985)
    at org.jboss.dependency.plugins.AbstractController.change(AbstractController.java:823)
    at org.jboss.dependency.plugins.AbstractController.change(AbstractController.java:553)
    at org.jboss.system.ServiceController.doChange(ServiceController.java:688)
    at org.jboss.system.ServiceController.start(ServiceController.java:460)
    at org.jboss.system.deployers.ServiceDeployer.start(ServiceDeployer.java:163)
    at org.jboss.system.deployers.ServiceDeployer.deploy(ServiceDeployer.java:99)
    at org.jboss.system.deployers.ServiceDeployer.deploy(ServiceDeployer.java:46)
    at org.jboss.deployers.spi.deployer.helpers.AbstractSimpleRealDeployer.internalDeploy(AbstractSimpleRealDeployer.java:62)
    at org.jboss.deployers.spi.deployer.helpers.AbstractRealDeployer.deploy(AbstractRealDeployer.java:50)
    at org.jboss.deployers.plugins.deployers.DeployerWrapper.deploy(DeployerWrapper.java:171)
    at org.jboss.deployers.plugins.deployers.DeployersImpl.doDeploy(DeployersImpl.java:1440)
    at org.jboss.deployers.plugins.deployers.DeployersImpl.doInstallParentFirst(DeployersImpl.java:1158)
    at org.jboss.deployers.plugins.deployers.DeployersImpl.doInstallParentFirst(DeployersImpl.java:1179)
    at org.jboss.deployers.plugins.deployers.DeployersImpl.install(DeployersImpl.java:1099)
    at org.jboss.dependency.plugins.AbstractControllerContext.install(AbstractControllerContext.java:348)
    at org.jboss.dependency.plugins.AbstractController.install(AbstractController.java:1633)
    at org.jboss.dependency.plugins.AbstractController.incrementState(AbstractController.java:935)
    at org.jboss.dependency.plugins.AbstractController.resolveContexts(AbstractController.java:1083)
    at org.jboss.dependency.plugins.AbstractController.resolveContexts(AbstractController.java:985)
    at org.jboss.dependency.plugins.AbstractController.change(AbstractController.java:823)
    at org.jboss.dependency.plugins.AbstractController.change(AbstractController.java:553)
    at org.jboss.deployers.plugins.deployers.DeployersImpl.process(DeployersImpl.java:782)
    at org.jboss.deployers.plugins.main.MainDeployerImpl.process(MainDeployerImpl.java:702)
    at org.jboss.system.server.profileservice.repository.MainDeployerAdapter.process(MainDeployerAdapter.java:117)
    at org.jboss.system.server.profileservice.repository.ProfileDeployAction.install(ProfileDeployAction.java:70)
    at org.jboss.system.server.profileservice.repository.AbstractProfileAction.install(AbstractProfileAction.java:53)
    at org.jboss.system.server.profileservice.repository.AbstractProfileService.install(AbstractProfileService.java:403)
    at org.jboss.dependency.plugins.AbstractControllerContext.install(AbstractControllerContext.java:348)
    at org.jboss.dependency.plugins.AbstractController.install(AbstractController.java:1633)
    at org.jboss.dependency.plugins.AbstractController.incrementState(AbstractController.java:935)
    at org.jboss.dependency.plugins.AbstractController.resolveContexts(AbstractController.java:1083)
    at org.jboss.dependency.plugins.AbstractController.resolveContexts(AbstractController.j开发者_运维技巧ava:985)
    at org.jboss.dependency.plugins.AbstractController.install(AbstractController.java:775)
    at org.jboss.dependency.plugins.AbstractController.install(AbstractController.java:540)
    at org.jboss.system.server.profileservice.repository.AbstractProfileService.registerProfile(AbstractProfileService.java:308)
    at org.jboss.system.server.profileservice.ProfileServiceBootstrap.start(ProfileServiceBootstrap.java:256)
    at org.jboss.bootstrap.AbstractServerImpl.start(AbstractServerImpl.java:461)
    at org.jboss.Main.boot(Main.java:221)
    at org.jboss.Main$1.run(Main.java:556)
    at java.lang.Thread.run(Unknown Source)
Caused by: org.springframework.beans.BeanInstantiationException: Could not instantiate bean class [com.dao.Services]: Constructor threw exception; nested exception is java.lang.NullPointerException
    at org.springframework.beans.BeanUtils.instantiateClass(BeanUtils.java:141)
    at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:71)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateBean(AbstractAutowireCapableBeanFactory.java:948)
    ... 82 more
Caused by: java.lang.NullPointerException
    at com.dao.Services.sess(Services.java:36)
    at com.dao.Services.<init>(Services.java:42)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source)
    at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source)
    at java.lang.reflect.Constructor.newInstance(Unknown Source)
    at org.springframework.beans.BeanUtils.instantiateClass(BeanUtils.java:126)
    ... 84 more

---

When a Service is instantiated, the query field is initialized. And at this time, the sessionFactory has not been injected, hence the NullPointerException.

But actually, the whole idea of initializing a Query at the Service creation time doesn't make much sense as queries are bound to the lifespan of a session. From the javadoc of Query:

Queries are executed by calling list(), scroll() or iterate(). A query may be re-executed by subsequent invocations. Its lifespan is, however, bounded by the lifespan of the Session that created it.

In other words, you should create a Query for each call, not once for all:

public class Services {
    protected SessionFactory sessionFactory;
    public void setSessionFactory(SessionFactory value) {
        sessionFactory = value;
    }

    public List foo() {
       Query query = sessionFactory.getCurrentSession().createQuery("....");
       ...
    }
}

---

Services gets instantiated without the session factory via the default constructor. Afterwards, setSession() is called by Spring. Java tries to initialize the member query right after instantiation, when Spring has not yet called setSession(). You will either have to inject the session factory via a parametrized constructor or initialize the member queryin setSession().