spring整合mybatis接口无法注入问题

时间：2021-08-16 19:53:10

在学习Spring完之后简单的了解了MyBatis。然后进行简单的整合，遇到MyBatista接口映射的Bean无法自动注入的问题；

代码异常：

线程“main”org.springframe .bean .factory中的异常。创建名为“UserController”的bean时出错:通过字段“userdao”表示的不满足的依赖关系;嵌套异常是org.springframe .bean .factory。BeanCreationException:在文件[C:\Users\li rui long\eclipse-workspace\MyBatis_Demo\build\classes\com\mybatis\dao\ userdao]中创建名为“userdao”的bean时出错。类]:在设置bean属性“sqlSessionFactory”时无法解析对bean“sqlSessionFactory”的引用;嵌套异常是org.springframe .bean .factory。BeanCreationException:在类路径资源[ApplicationContext]中定义名称为“sqlSessionFactory”的bean创建错误。:设置bean属性“dataSource”时不能解析对bean“dataSource”的引用;嵌套异常是org.springframe .bean .factory。BeanCreationException:创建名为“dataSource”的bean时出错:查找方法解析失败;嵌套异常是java.lang。IllegalStateException:未能从ClassLoader [jdk.internal.loader.ClassLoader . $AppClassLoader@77a567e1]内检类[org.apache.commons.dbcp2.BasicDataSource]

异常提示，控制器层的Bean无法创建，原因是MyBatis对应的映射接口无法完成映射，无法生成DAO层的Bean；

所以问题应该出现在XML文件里，

测试类，13行报错：

 package com.mybatis.test;

 import org.springframework.context.ApplicationContext;

 import org.springframework.context.support.ClassPathXmlApplicationContext;

 import com.mybatis.controller.UserController;

 public class Test_Controller {

     public static void main(String[] args) {

         // TODO Auto-generated method stub

         ApplicationContext app = new ClassPathXmlApplicationContext("ApplicationContext.xml");

         UserController coll = (UserController) app.getBean("UserController");

         coll.test();

     }

 }

对ApplicationContext.xml配置文件进行一步步排查：

<?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:tx="http://www.springframework.org/schema/tx"

        xsi:schemaLocation="

        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.xsd

        http://www.springframework.org/schema/tx

        http://www.springframework.org/schema/tx/spring-tx.xsd">

 <!-- 指定需要扫描的包，使注解生效 -->

 <context:component-scan base-package="com.mybatis.po"/>

 <context:component-scan base-package="com.mybatis.dao"/>

 <context:component-scan base-package="com.mybatis.Controller"/>

 <!-- 配置数据源 -->

<bean id="dataSource" class="org.apache.commons.dbcp2.BasicDataSource" destroy-method="close">

 <property name="driverClassName" value = "com.mysql.jdbc.Driver"/>

 <property name="url" value  ="jdbc:mysql://localhost:3306/Springtest?characterEncoding=utf8"/>

 <property name="username" value = "root"/>

 <property name="password" value ="mysql" />

       <!--  可同时连接的最大的连接数 -->

        <property name="maxActive" value="60" />

       <!--  最大的空闲的连接数 -->

        <property name="maxTotal" value="60" />

       <!--  最小的空闲的连接数，低于这个数量会被创建新的连接，默认为0  -->

        <property name="maxIdle" value="5" />

        <!-- 连接池启动时创建的初始化连接数量，默认值为0 -->

        <property name="initialSize" value="5" />

 </bean>

 <!-- 添加事务支持 -->

 <bean id = "txManager" class = "org.springframework.jdbc.datasource.DataSourceTransactionManager">

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

 </bean>

 <!-- 开启事务注解 -->

 <tx:annotation-driven transaction-manager ="txManager"/>

 <!-- 配置Mybatis工厂，同时指定数据源，并与MyBatista完美结合 -->

 <bean id="sqlSessionFactory" class = "org.mybatis.spring.SqlSessionFactoryBean">

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

     <!-- configLocation 的属性为Mybatis 的核心配置文件 -->

     <property name = "configLocation" value = "classpath:mybatis-config.xml"></property>

  </bean>

  <!-- Mapper 代理开发，使用Spring自动扫描MyBatista的接口并装配 -->

  <!-- Spring 将指定包中所有的被@Mapper注解标注的接口自动装配为MyBatatis的映射接口 -->

  <bean class = "org.mybatis.spring.mapper.MapperScannerConfigurer">

  <!-- MyBatis-spring组件的扫描器 -->

  <property name="basePackage" value = "com.mybatis.dao"/>

  <property name="sqlSessionFactoryBeanName" value = "sqlSessionFactory"/>

  </bean>

 </beans>
  1. 检查扫描的包名,是否有写错或者少写的。
  2. 确定数据源的配置正常，我的问题就出在这里，修改数据库配置信息(密码等)，看是否会报不一样的错，当还是原来的错，说明配置文件没有加载或者数据源错误。我用的DBCP数据源(需要导入两个包DBCP+连接池包)，修改密码后还是报同样的错误所以我尝试着用Spring自带的数据源，解决了问题，正确代码： 
     <?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:tx="http://www.springframework.org/schema/tx"
    
         xsi:schemaLocation="
    
         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.xsd
    
         http://www.springframework.org/schema/tx
    
         http://www.springframework.org/schema/tx/spring-tx.xsd">
    
  <!-- 指定需要扫描的包，使注解生效 -->

  <context:component-scan base-package="com.mybatis.po"/>
    
  <context:component-scan base-package="com.mybatis.dao"/>
    
  <context:component-scan base-package="com.mybatis.Controller"/>
    
  <!-- 配置数据源 -->
    
 <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/Springtest?characterEncoding=utf8"/>
    
  <property name="username" value = "root"/>
    
  <property name="password" value ="mysql" />
    
  </bean>  

  <!-- 添加事务支持 -->
    
  <bean id = "txManager" class = "org.springframework.jdbc.datasource.DataSourceTransactionManager">
    
  <property name = "dataSource" ref = "dataSource"/>
    
  </bean>
    
  <!-- 开启事务注解 -->
    
  <tx:annotation-driven transaction-manager ="txManager"/>
    
  <!-- 配置Mybatis工厂，同时指定数据源，并与MyBatista完美结合 -->
    
  <bean id="sqlSessionFactory" class = "org.mybatis.spring.SqlSessionFactoryBean">
    
      <property name="dataSource" ref ="dataSource"/>
    
      <!-- configLocation 的属性为Mybatis 的核心配置文件 -->
    
      <property name = "configLocation" value = "classpath:mybatis-config.xml"></property>
    
   </bean>
    
   <!-- Mapper 代理开发，使用Spring自动扫描MyBatista的接口并装配 -->
    
   <!-- Spring 将指定包中所有的被@Mapper注解标注的接口自动装配为MyBatatis的映射接口 -->
    
   <bean class = "org.mybatis.spring.mapper.MapperScannerConfigurer">
    
   <!-- MyBatis-spring组件的扫描器 -->
    
   <property name="basePackage" value = "com.mybatis.dao"/>
    
   <property name="sqlSessionFactoryBeanName" value = "sqlSessionFactory"/>
    
   </bean>

  </beans>
  3. 检查对应的依赖类，配置文件路径能否Ctrl进去。MyBatis的核心文件和映射文件路径是否正确。以下是我的代码：
  4. <?xml version="1.0" encoding="UTF-8" ?>
    
<!DOCTYPE configuration
    
        PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
    
        "http://mybatis.org/dtd/mybatis-3-config.dtd">
    
<configuration>
    
    <mappers>
    
    <!-- 映射文件-->
    
    <mapper resource = "com/mybatis/dao/UserMapper.xml"/>
    
    </mappers>
    
</configuration
     
  5. <?xml version="1.0" encoding="UTF-8"?>
    
<!DOCTYPE mapper
    
  PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
    
  "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
    
<mapper namespace = "com.mybatis.dao.UserDao">
    
    <!-- 根据ID查询用户信息 -->
    
    <select id="selectUserById" parameterType = "Integer" resultType = "com.mybatis.po.Myuser">
    
    SELECT * FROM user WHERE uid = #{uid}
    
    </select>
    
    <!--
    
    <select id="selectAllUser" resultType = "com.mybatis.po.Myuser">
    
    SELECT * FROM user
    
    </select>
    
    添加一个用户，#{uname}为com.mybatis.po.MyUser属性值
    
    <insert id ="addUser" parameterType = "com.mybatis.po.Myuser">
    
    INSERT INTO user (uname,usex) VALUES (#{uname},#{usex})
    
    </insert>
    
    修改一个用户
    
    <update id="updateUser" parameterType = "com.mybatis.po.Myuser">
    
    UPDATE user SET uname = #{unmae},usex = #{user} where uid = #{uid}
    
    </update>
    
    删除一个用户
    
    <delete id = "delectUser" parameterType = "Integer">
    
    DELECT from user WHERE uid = #{uid}
    
    </delete> -->
    
</mapper >

    看Dao层的接口和Mapped的映射文件是否是在同一包下。

类似问题的博客：

https://blog.csdn.net/h363659487/article/details/74275972

https://blog.csdn.net/u012385190/article/details/53186552

         嗯嗯，第一次写这样的博客，希望会对大家有帮助！！，愿我们都被温柔以待！2019.4.21。

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