我把详细代码贴出来，各位大神帮忙看看是什么情况导致sessionFactory为空

BaseDaoImpl代码如下：

package cn.itcast.oa.base;

import java.lang.reflect.ParameterizedType;
import java.util.List;

import javax.annotation.Resource;

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import org.springframework.transaction.annotation.Transactional;

@SuppressWarnings("unchecked")
public class BaseDaoImpl<T> implements BaseDao<T>{

//	@Resource
	@Autowired
	protected  SessionFactory sessionFactory;

	private Class<T> clazz = null;

	public BaseDaoImpl(){
		ParameterizedType pt = (ParameterizedType) this.clazz.getGenericSuperclass();
		this.clazz = (Class<T>)pt.getActualTypeArguments()[0];
	}

	protected Session getSession(){
		System.out.println(sessionFactory);
//		Session session = getSessionFactory().getCurrentSession();
		Session session = sessionFactory.getCurrentSession();
		System.out.println(session+"=====获得session");
		return session;
	}

	@Transactional
	public void save(T entity) {
		getSession().save(entity);
	}

	public void update(T entity) {
		getSession().update(entity);
	}

	public void delete(long id) {
		Object obj = getById(id);
		if(obj != null){
			getSession().delete(obj);
		}
	}

	public List<T> findAll() {
		return getSession().createQuery("from"+clazz.getSimpleName()).list();
	}

	public List<T> getByIds(List<Long> ids) {
		return getSession().createQuery(//
				"from User where id in(:ids)")//
				.setParameterList("ids", ids)//
				.list();
	}

	public T getById(long id) {

		return (T) getSession().get(clazz, id);
	}

}

UserDaoImpl代码如下：

package cn.itcast.oa.dao.impl;

import org.springframework.stereotype.Service;

import cn.itcast.oa.base.BaseDaoImpl;
import cn.itcast.oa.dao.UserDao;
import cn.itcast.oa.entity.User;

@Service
public class UserDaoImpl extends BaseDaoImpl<User> implements UserDao{

}

applicationContext.xml代码如下：

<beans xmlns="http://www.springframework.org/schema/beans"
               xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
               xmlns:context="http://www.springframework.org/schema/context"
               xmlns:tx="http://www.springframework.org/schema/tx"
               xsi:schemaLocation="http://www.springframework.org/schema/beans 
               http://www.springframework.org/schema/beans/spring-beans-2.5.xsd
               http://www.springframework.org/schema/context 
               http://www.springframework.org/schema/context/spring-context-2.5.xsd
               http://www.springframework.org/schema/tx 
               http://www.springframework.org/schema/tx/spring-tx-2.5.xsd">

	<!--自动扫名与装配  -->
	<context:component-scan base-package="cn.itcast.oa"/>

	<!--导入外部jdbc配置文件  -->
	<context:property-placeholder location="classpath:jdbc.properties"/>

	<!-- 配置SessionFactory -->
	<bean id="sessionFactory" class="org.springframework.orm.hibernate3.LocalSessionFactoryBean">
			<!-- 指定hibernate配置文件指定路径 -->
			<property name="configLocation" value="classpath:hibernate.cfg.xml"></property>
			<!-- 配置c3p0数据库连接池 -->
			<property name="dataSource">
				<bean class="com.mchange.v2.c3p0.ComboPooledDataSource">
					<!-- 数据库连接信息 -->
					<property name="jdbcUrl" value="${jdbcUrl}"></property>
					<property name="driverClass" value="${driverClass}"></property>
					<property name="user" value="${user}"></property>
					<property name="password" value="${password}"></property>
				</bean>
			</property>
	</bean>
	<!-- 
	<bean id="userDao">
		<property name="sessionFactory" ref="sessionFactory"></property>
	</bean>
	 -->
	<!-- 配置申明式事务管理 -->
	<bean id="txManager" class="org.springframework.orm.hibernate3.HibernateTransactionManager">
		<property name="sessionFactory" ref="sessionFactory"></property>
	</bean>

	<!-- 采用注解方式开启事务 -->
	<tx:annotation-driven transaction-manager="txManager"/>
</beans>

启动tomcat就报异常如下：

严重: Exception sending context initialized event to listener instance of class org.springframework.web.context.ContextLoaderListener
org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'roleDaoImpl' defined in file [E:\javaDevTools\apache-tomcat-6.0.41\webapps\ssh5test\WEB-INF\classes\cn\itcast\oa\dao\impl\RoleDaoImpl.class]: Instantiation of bean failed; nested exception is org.springframework.beans.BeanInstantiationException: Could not instantiate bean class [cn.itcast.oa.dao.impl.RoleDaoImpl]: Constructor threw exception; nested exception is java.lang.NullPointerException
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateBean(AbstractAutowireCapableBeanFactory.java:997)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:943)
	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:294)
	at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:225)
	at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:291)
	at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:193)
	at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:605)
	at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:925)
	at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:472)
	at org.springframework.web.context.ContextLoader.configureAndRefreshWebApplicationContext(ContextLoader.java:383)
	at org.springframework.web.context.ContextLoader.initWebApplicationContext(ContextLoader.java:283)
	at org.springframework.web.context.ContextLoaderListener.contextInitialized(ContextLoaderListener.java:111)
	at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:4210)
	at org.apache.catalina.core.StandardContext.start(StandardContext.java:4709)
	at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:799)
	at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:779)
	at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:583)
	at org.apache.catalina.startup.HostConfig.deployDirectory(HostConfig.java:1079)
	at org.apache.catalina.startup.HostConfig.deployDirectories(HostConfig.java:1002)
	at org.apache.catalina.startup.HostConfig.deployApps(HostConfig.java:506)
	at org.apache.catalina.startup.HostConfig.start(HostConfig.java:1317)
	at org.apache.catalina.startup.HostConfig.lifecycleEvent(HostConfig.java:324)
	at org.apache.catalina.util.LifecycleSupport.fireLifecycleEvent(LifecycleSupport.java:142)
	at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1065)
	at org.apache.catalina.core.StandardHost.start(StandardHost.java:822)
	at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1057)
	at org.apache.catalina.core.StandardEngine.start(StandardEngine.java:463)
	at org.apache.catalina.core.StandardService.start(StandardService.java:525)
	at org.apache.catalina.core.StandardServer.start(StandardServer.java:754)
	at org.apache.catalina.startup.Catalina.start(Catalina.java:595)
	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)
	at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:289)
	at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:414)
Caused by: org.springframework.beans.BeanInstantiationException: Could not instantiate bean class [cn.itcast.oa.dao.impl.RoleDaoImpl]: Constructor threw exception; nested exception is java.lang.NullPointerException
	at org.springframework.beans.BeanUtils.instantiateClass(BeanUtils.java:162)
	at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:87)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateBean(AbstractAutowireCapableBeanFactory.java:990)
	... 37 more
Caused by: java.lang.NullPointerException
	at cn.itcast.oa.base.BaseDaoImpl.<init>(BaseDaoImpl.java:38)
	at cn.itcast.oa.dao.impl.RoleDaoImpl.<init>(RoleDaoImpl.java:10)
	at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
	at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:39)
	at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27)
	at java.lang.reflect.Constructor.newInstance(Constructor.java:513)
	at org.springframework.beans.BeanUtils.instantiateClass(BeanUtils.java:147)
	... 39 more
2014-8-11 17:11:21 org.apache.catalina.core.StandardContext start
严重: Error listenerStart
2014-8-11 17:11:21 org.apache.catalina.core.StandardContext start
严重: Context [/ssh5test] startup failed due to previous errors

已困扰两天，求大神帮忙

7 个解决方案

#1

  <bean id="userDao">
        <property name="sessionFactory" ref="sessionFactory"></property>
    </bean>

Caused by: java.lang.NullPointerException
    at cn.itcast.oa.base.BaseDaoImpl.<init>(BaseDaoImpl.java:38)
    at cn.itcast.oa.dao.impl.RoleDaoImpl.<init>(RoleDaoImpl.java:10
有没有 RoleDao

[cn.itcast.oa.dao.impl.RoleDaoImpl]:

#2

我测试的时候是sessionFactory未null所引起的。我用的注解方式。userDaoImpl就没有在applicationContext.xml 中配置。

#3

严重: Exception sending context initialized event to listener instance of class org.springframework.web.context.ContextLoaderListener
org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'roleDaoImpl' defined in file [E:\javaDevTools\apache-tomcat-6.0.41\webapps\ssh5test\WEB-INF\classes\cn\itcast\oa\dao\impl\RoleDaoImpl.class]: Instantiation of bean failed; nested exception is org.springframework.beans.BeanInstantiationException: Could not instantiate bean class [cn.itcast.oa.dao.impl.RoleDaoImpl]: Constructor threw exception; nested exception is java.lang.NullPointerException
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateBean(AbstractAutowireCapableBeanFactory.java:997)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:943)
	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:294)
	at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:225)
	at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:291)
	at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:193)
	at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:605)
	at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:925)
	at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:472)
	at org.springframework.web.context.ContextLoader.configureAndRefreshWebApplicationContext(ContextLoader.java:383)
	at org.springframework.web.context.ContextLoader.initWebApplicationContext(ContextLoader.java:283)
	at org.springframework.web.context.ContextLoaderListener.contextInitialized(ContextLoaderListener.java:111)
	at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:4210)
	at org.apache.catalina.core.StandardContext.start(StandardContext.java:4709)
	at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:799)
	at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:779)
	at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:583)
	at org.apache.catalina.startup.HostConfig.deployDirectory(HostConfig.java:1079)
	at org.apache.catalina.startup.HostConfig.deployDirectories(HostConfig.java:1002)
	at org.apache.catalina.startup.HostConfig.deployApps(HostConfig.java:506)
	at org.apache.catalina.startup.HostConfig.start(HostConfig.java:1317)
	at org.apache.catalina.startup.HostConfig.lifecycleEvent(HostConfig.java:324)
	at org.apache.catalina.util.LifecycleSupport.fireLifecycleEvent(LifecycleSupport.java:142)
	at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1065)
	at org.apache.catalina.core.StandardHost.start(StandardHost.java:822)
	at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1057)
	at org.apache.catalina.core.StandardEngine.start(StandardEngine.java:463)
	at org.apache.catalina.core.StandardService.start(StandardService.java:525)
	at org.apache.catalina.core.StandardServer.start(StandardServer.java:754)
	at org.apache.catalina.startup.Catalina.start(Catalina.java:595)
	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)
	at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:289)
	at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:414)
Caused by: org.springframework.beans.BeanInstantiationException: Could not instantiate bean class [cn.itcast.oa.dao.impl.RoleDaoImpl]: Constructor threw exception; nested exception is java.lang.NullPointerException
	at org.springframework.beans.BeanUtils.instantiateClass(BeanUtils.java:162)
	at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:87)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateBean(AbstractAutowireCapableBeanFactory.java:990)
	... 37 more
Caused by: java.lang.NullPointerException
	at cn.itcast.oa.base.BaseDaoImpl.<init>(BaseDaoImpl.java:38)
	at cn.itcast.oa.dao.impl.RoleDaoImpl.<init>(RoleDaoImpl.java:10)
	at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
	at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:39)
	at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27)
	at java.lang.reflect.Constructor.newInstance(Constructor.java:513)
	at org.springframework.beans.BeanUtils.instantiateClass(BeanUtils.java:147)
	... 39 more
2014-8-11 17:43:54 org.apache.catalina.core.StandardContext start
严重: Error listenerStart
2014-8-11 17:43:54 org.apache.catalina.core.StandardContext start
严重: Context [/ssh5test] startup failed due to previous errors

at cn.itcast.oa.base.BaseDaoImpl.<init>(BaseDaoImpl.java:38)------------------->38行对应ParameterizedType pt = (ParameterizedType) this.clazz.getGenericSuperclass();

#4

你打印出来的sessionFactory是null？你在dao的实现类上加上注解试试

#5

ParameterizedType pt = (ParameterizedType) this.clazz.getGenericSuperclass();
这个clazz变量在哪里初始化了呢？

#6

sessionFactory 注入到哪了，还有注解 是否可以继承的问题？

#7

你先测试下，先获取applicationContext.xml，在获取sessionFactory看看能不能获取到sessionFactory