我创建了一个maven项目，并通过pom.xml添加了Spring4，Hibernate4libs我尝试将我的web应用程序与在PostgreSQL中创建的数据库链接，但当我在apache tomcat 7中发布我的项目时，出现以下异常：
org.springframework.beans.factory.BeanCreationException:创建ServletContext资源[/WEB-INF/applicationContext.xml]中定义的名为“emf”的bean时出错：调用init方法失败;嵌套异常为java. lang. IllegalArgumentException：EntityManagerFactory配置中未指定PersistenceProvider，并且所选PersistenceUnitInfo在org中也未指定提供程序类名。SpringFramework豆子工厂。支持。AbstractAutowireCapableBeanFactory. initializeBean（AbstractAutowireCapableBeanFactory.java：1553）at org. SpringFramework豆子工厂。支持。AbstractAutowireCapableBeanFactory. doCreateBean（AbstractAutowireCapableBeanFactory.java：539）at org. SpringFramework豆子工厂。支持。AbstractAutowireCapableBeanFactory. createBean（AbstractAutowireCapableBeanFactory.java：475）at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject（AbstractBeanFactory.java：304）at org. SpringFramework豆子工厂。支持。DefaultSingletonBeanRegistry。getSingleton（DefaultSingletonBeanRegistry.java：228）at org. SpringFramework豆子工厂。支持。AbstractBeanFactory. org上的doGetBean（AbstractBeanFactory.java：300）。SpringFramework豆子工厂。支持。AbstractBeanFactory. getBean（AbstractBeanFactory.java：195）at org. SpringFramework上下文支持。AbstractApplicationContext。getBean（AbstractApplicationContext.java：973）at org. SpringFramework上下文支持。AbstractApplicationContext。finishBeanFactoryInitialization（AbstractApplicationContext.java：750）at org. SpringFramework上下文支持。AbstractApplicationContext。在org上刷新（AbstractApplicationContext.java：482）。SpringFramework web. context. ContextLoader。org上的configureAndRefreshWebApplicationContext（ContextLoader.java：403）。SpringFramework web. context. ContextLoader。org上的initWebApplicationContext（ContextLoader.java：306）。SpringFramework web. context. ContextLoaderListener。org上的contextInitialized（ContextLoaderListener.java：106）。Apachecatalina核心StandardContext。listenerStart（StandardContext.java：4994）at org.Apachecatalina核心StandardContext。startInternal（StandardContext.java：5492）at org.Apachecatalina效用LifecycleBase. start（LifecycleBase.java：150）at org.Apachecatalina核心ContainerBase $ www.example.com EntityManagerFactory配置中未指定PersistenceProvider，并且所选PersistenceUnitInfo在org中也未指定提供程序类名。SpringFramework orm. LocalContainerEntityManagerFactoryBean。createNativeEntityManagerFactory（LocalContainerEntityManagerFactoryBean.java：318）at org. SpringFramework orm. AbstractEntityManagerFactoryBean。afterPropertiesSet（AbstractEntityManagerFactoryBean.java：318）at org. SpringFramework豆子工厂。支持。AbstractAutowireCapableBeanFactory. invokeInitMethods（AbstractAutowireCapableBeanFactory.java：1612）at org. SpringFramework豆子工厂。支持。AbstractAutowireCapableBeanFactory. initializeBean（AbstractAutowireCapableBeanFactory.java：1549）...StartChild.call
下面是我applicationContext.xml：

<?xml version="1.0" encoding="UTF-8"?>
<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:jdbc="http://www.springframework.org/schema/jdbc"
    xmlns:tx="http://www.springframework.org/schema/tx"
    xsi:schemaLocation="http://www.springframework.org/schema/jdbc http://www.springframework.org/schema/jdbc/spring-jdbc-4.0.xsd
        http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.0.xsd
        http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-4.0.xsd">

    <context:component-scan base-package="com.medsoft.stadto">
        <context:exclude-filter type="annotation" expression="org.springframework.stereotype.Controller"/>
    </context:component-scan>

    <bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource">
        <property name="driverClassName" value="org.postgresql.Driver" />
        <property name="url" value="jdbc:postgresql://localhost:1993/Posts" />
        <property name="username" value="postgres" />
        <property name="password" value="123" />
    </bean>

    <bean class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean" id="emf">
        <property name="packagesToScan" value="com.medsoft.stadto.entity" />
        <property name="dataSource" ref="dataSource" />
        <property name="jpaProperties">
            <props>
                <prop key="hibernate.show_sql">true</prop>
                <prop key="hibernate.hbm2dll.auto">create</prop>
            </props>
        </property>
    </bean>

    <tx:annotation-driven transaction-manager="txManager" />
    <bean id="txManager" class="org.springframework.orm.jpa.JpaTransactionManager">
        <property name="dataSource" ref="dataSource" />
    </bean>

</beans>