java.lang.ClassCastException：org.springframework.jdbc.datasource.DriverManagerDataSource无法强制转换为java.lang.String

Question

org.springframework.beans.factory.BeanCreationException：在ServletContext资源[/WEB-INF/mvc-dispatcher.xml]中定义了名为'sessionFactory'的bean时出错：init方法的调用失败;嵌套异常是java.lang.ClassCastException：org.springframework.jdbc.datasource.DriverManagerDataSource无法强制转换为java.lang.String

我的弹簧配置文件是

    <?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:util="http://www.springframework.org/schema/util" xmlns:mvc="http://www.springframework.org/schema/mvc"
 xsi:schemaLocation="http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-4.1.xsd
  http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
  http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util-4.1.xsd
  http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.1.xsd">

 <context:component-scan base-package="org.techy9.controller" />
 <mvc:resources mapping="/images/**" location="/images/" />  
 <context:property-placeholder location="classpath:database.properties" />
 <mvc:annotation-driven />

 <bean id="dataSource"
  class="org.springframework.jdbc.datasource.DriverManagerDataSource">
  <property name="driverClassName" value="com.mysql.jdbc.Driver" />
  <property name="url" value="jdbc:mysql://localhost:3306/techy9" />
  <property name="username" value="root" />
  <property name="password" value="root" />
 </bean>

 <bean id="sessionFactory"
  class="org.springframework.orm.hibernate4.LocalSessionFactoryBean">
  <property name="dataSource" ref="dataSource" /> 

  <property name="configLocation" value="classpath:hibernate.cfg.xml" /> 

 </bean>


 <bean id="txManager"
  class="org.springframework.orm.hibernate4.HibernateTransactionManager">
  <property name="sessionFactory" ref="sessionFactory" />
 </bean>

 <bean id="persistenceExceptionTranslationPostProcessor"
  class="org.springframework.dao.annotation.PersistenceExceptionTranslationPostProcessor" /> 

 <bean
  class="org.springframework.web.servlet.view.InternalResourceViewResolver">
  <property name="prefix">
   <value>/WEB-INF/</value>
  </property>
  <property name="suffix">
   <value>.jsp</value>
  </property>
 </bean>




 <bean id="mailSender" class="org.springframework.mail.javamail.JavaMailSenderImpl">
        <property name="host" value="smtp.gmail.com" />
        <property name="port" value="587" />
        <property name="username" value="praveen201501@gmail.com" />
        <property name="password" value="krishna2016" />
        <property name="javaMailProperties">
            <props>
                <prop key="mail.smtp.auth">true</prop>
                <prop key="mail.smtp.starttls.enable">true</prop>
                <prop key="mail.smtp.ssl.trust">smtp.gmail.com</prop>
            </props>
        </property>
    </bean>

     <bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver"/>
</beans>

    WARNING: Exception encountered during context initialization - cancelling refresh attempt
org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'sessionFactory' defined in ServletContext resource [/WEB-INF/mvc-dispatcher.xml]: Invocation of init method failed; nested exception is java.lang.ClassCastException: org.springframework.jdbc.datasource.DriverManagerDataSource cannot be cast to java.lang.String
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1574)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:539)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:476)
    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:303)
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230)
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:299)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:194)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:736)
    at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:757)
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:480)
    at org.springframework.web.servlet.FrameworkServlet.configureAndRefreshWebApplicationContext(FrameworkServlet.java:663)
    at org.springframework.web.servlet.FrameworkServlet.createWebApplicationContext(FrameworkServlet.java:629)
    at org.springframework.web.servlet.FrameworkServlet.createWebApplicationContext(FrameworkServlet.java:677)
    at org.springframework.web.servlet.FrameworkServlet.initWebApplicationContext(FrameworkServlet.java:548)
    at org.springframework.web.servlet.FrameworkServlet.initServletBean(FrameworkServlet.java:489)
    at org.springframework.web.servlet.HttpServletBean.init(HttpServletBean.java:136)
    at javax.servlet.GenericServlet.init(GenericServlet.java:158)
    at org.apache.catalina.core.StandardWrapper.initServlet(StandardWrapper.java:1284)
    at org.apache.catalina.core.StandardWrapper.loadServlet(StandardWrapper.java:1197)
    at org.apache.catalina.core.StandardWrapper.load(StandardWrapper.java:1087)
    at org.apache.catalina.core.StandardContext.loadOnStartup(StandardContext.java:5253)
    at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5543)
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
    at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1574)
    at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1564)
    at java.util.concurrent.FutureTask.run(Unknown Source)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
    at java.lang.Thread.run(Unknown Source)
Caused by: java.lang.ClassCastException: org.springframework.jdbc.datasource.DriverManagerDataSource cannot be cast to java.lang.String
    at org.hibernate.util.PropertiesHelper.resolvePlaceHolders(PropertiesHelper.java:88)
    at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:1161)
    at org.springframework.orm.hibernate4.LocalSessionFactoryBuilder.buildSessionFactory(LocalSessionFactoryBuilder.java:372)
    at org.springframework.orm.hibernate4.LocalSessionFactoryBean.buildSessionFactory(LocalSessionFactoryBean.java:454)
    at org.springframework.orm.hibernate4.LocalSessionFactoryBean.afterPropertiesSet(LocalSessionFactoryBean.java:439)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1633)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1570)
    ... 28 more