spring整合mybatis接口无法注入问题

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作者:意必固我

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:Usersli rui longeclipse-workspaceMyBatis_Demobuildclassescommybatisdao 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：

 1 package com.mybatis.test;
 2 
 3 import org.springframework.context.ApplicationContext;
 4 import org.springframework.context.support.ClassPathXmlApplicationContext;
 5 
 6 import com.mybatis.controller.UserController;
 7 
 8 
 9 public class Test_Controller {
10 
11     public static void main(String[] args) {
12         // TODO Auto-generated method stub
13         ApplicationContext app = new ClassPathXmlApplicationContext("ApplicationContext.xml");
14         UserController coll = (UserController) app.getBean("UserController");
15         coll.test();
16     }
17 
18 }

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>

检查扫描的包名,是否有写错或者少写的。

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：

 1 <?xml version="1.0" encoding="UTF-8"?>
 2 <beans  xmlns="http://www.springframework.org/schema/beans"
 3         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 4         xmlns:context="http://www.springframework.org/schema/context"
 5         xmlns:tx="http://www.springframework.org/schema/tx"
 6         xsi:schemaLocation="
 7         http://www.springframework.org/schema/beans
 8         http://www.springframework.org/schema/beans/spring-beans.xsd
 9         http://www.springframework.org/schema/context
10         http://www.springframework.org/schema/context/spring-context.xsd
11         http://www.springframework.org/schema/tx
12         http://www.springframework.org/schema/tx/spring-tx.xsd">
13  <!-- 指定需要扫描的包，使注解生效 -->
14 
15  <context:component-scan base-package="com.mybatis.po"/>
16  <context:component-scan base-package="com.mybatis.dao"/>
17  <context:component-scan base-package="com.mybatis.Controller"/>
18  <!-- 配置数据源 -->
19 <bean id = "dataSource" class = "org.springframework.jdbc.datasource.DriverManagerDataSource">
20  <property name="driverClassName" value = "com.mysql.jdbc.Driver"/>
21  <property name="url" value  ="jdbc:mysql://localhost:3306/Springtest?characterEncoding=utf8"/>
22  <property name="username" value = "root"/>
23  <property name="password" value ="mysql" />
24  </bean>  
25  
26  <!-- 添加事务支持 -->
27  <bean id = "txManager" class = "org.springframework.jdbc.datasource.DataSourceTransactionManager">
28  <property name = "dataSource" ref = "dataSource"/>
29  </bean>
30  <!-- 开启事务注解 -->
31  <tx:annotation-driven transaction-manager ="txManager"/>
32  <!-- 配置Mybatis工厂，同时指定数据源，并与MyBatista完美结合 -->
33  <bean id="sqlSessionFactory" class = "org.mybatis.spring.SqlSessionFactoryBean">
34      <property name="dataSource" ref ="dataSource"/>
35      <!-- configLocation 的属性为Mybatis 的核心配置文件 -->
36      <property name = "configLocation" value = "classpath:mybatis-config.xml"></property>
37   </bean>
38   <!-- Mapper 代理开发，使用Spring自动扫描MyBatista的接口并装配 -->
39   <!-- 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 -->
40   <bean class = "org.mybatis.spring.mapper.MapperScannerConfigurer">
41   <!-- MyBatis-spring组件的扫描器 -->
42   <property name="basePackage" value = "com.mybatis.dao"/>
43   <property name="sqlSessionFactoryBeanName" value = "sqlSessionFactory"/> 
44   </bean>
45   
46  </beans>

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：

<?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

<?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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spring整合mybatis接口无法注入问题