springmvc 执行@Test报错

org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'userDao' defined in class path resource [spring/bean.xml]: Instantiation of bean failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [com.chen.ssm.dao.UserDao]: Specified class is an interface

......

Caused by: org.springframework.beans.BeanInstantiationException: Failed to instantiate [com.chen.ssm.dao.UserDao]: Specified class is an interface

问题描述：不能实例化[com.chen.ssm.dao.UserDao]这个对象

解决方法：
1、查看问题提示：主要注意Caused by: 后的信息提示
2、UserDao是个接口，UserDaoImpl是实现类

public interface UserDao {

    //根据id查询用户信息
    public User findUserById(int id) throws Exception;
}

public class UserDaoImpl extends SqlSessionDaoSupport implements UserDao {

    public User findUserById(int id) throws Exception {
        // 继承SqlSessionDaoSupport，通过this.getSqlSession()得到sqlSession
        SqlSession sqlSession = this.getSqlSession();

        User user = sqlSession.selectOne("test.findUserById",id);

        return user;
    }

}

3、注意核心配置文件将两个类的连接

  
<beans xmlns="http://www.springframework.org/schema/beans"  
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"  
    xmlns:aop="http://www.springframework.org/schema/aop"  
    xmlns:mvc="http://www.springframework.org/schema/mvc"  
    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-4.2.xsd  
        http://www.springframework.org/schema/tx  
        http://www.springframework.org/schema/tx/spring-tx-4.2.xsd  
        http://www.springframework.org/schema/aop  
        http://www.springframework.org/schema/aop/spring-aop-4.2.xsd  
        http://www.springframework.org/schema/context  
        http://www.springframework.org/schema/context/spring-context-4.2.xsd  
        http://www.springframework.org/schema/mvc  
        http://www.springframework.org/schema/mvc/spring-mvc-4.2.xsd"> 

    
    <context:property-placeholder location="classpath:db.properties"/>

    
    <bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource" destroy-method="close">  
      <property name="driverClassName" value="${jdbc.driver}"/>  
      <property name="url" value="${jdbc.url}"/>  
      <property name="username" value="${jdbc.username}"/>  
      <property name="password" value="${jdbc.password}"/>
      <property name="maxActive" value="10"/>
      <property name="maxIdle" value="5"/>
    bean>

    
    <bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
        
        <property name="configLocation" value="mybatis/SqlMapConfig.xml"/>

        
        <property name="dataSource" ref="dataSource"/>
    bean> 

         
    <bean id="userDao" class="com.chen.ssm.dao.UserDao">
        <property name="sqlSessionFactory" ref="sqlSessionFactory"/>
    bean>     

beans>

忽然记得以前配置spring-hibernate核心配置文件时，好像将它们之间的路径写错过，最后发现

     
    <bean id="userDao" class="com.chen.ssm.dao.UserDao">
        <property name="sqlSessionFactory" ref="sqlSessionFactory"/>
    bean>     

里的class路径确实写错了，应该写成实现类的路径，修改如下

id="userDao" class="com.chen.ssm.dao.UserDaoImpl">
        <property name="sqlSessionFactory" ref="sqlSessionFactory"/>