spring整合mybatis接口无法注入问题

 

          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：

 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>

 

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：

    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>

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。