记录错误：Error creating bean with name ‘userService‘: Unsatisfied dependency expressed through field

辣白菜饭包解决方案 2023-03-10 35 0 原文

控制台报错：

13:38:12.211 [RMI TCP Connection(3)-127.0.0.1] ERROR org.springframework.web.context.ContextLoader - Context initialization failed
org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'userService': Unsatisfied dependency expressed through field 'userMapper'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'userMapper' defined in file [E:\project\crm-project\crm\target\crm\WEB-INF\classes\com\bjpowernode\crm\settings\mapper\UserMapper.class]: Cannot resolve reference to bean 'sqlSessionFactory' while setting bean property 'sqlSessionFactory'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'sqlSessionFactory' defined in class path resource [applicationContext-datasource.xml]: Cannot resolve reference to bean 'dataSource' while setting bean property 'dataSource'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'dataSource' defined in class path resource [applicationContext-datasource.xml]: Error setting property values; nested exception is org.springframework.beans.PropertyBatchUpdateException; nested PropertyAccessExceptions (1) are:
PropertyAccessException 1: org.springframework.beans.MethodInvocationException: Property 'driverClassName' threw exception; nested exception is java.lang.IllegalStateException: Could not load JDBC driver class [com.mysql.cj.jdbc.Driver]

查了两个小时的错误，一直以为错误原因在userService和userMapper里。但实际上是数据库驱动的问题，虽然这里还没有用到数据库.....

原因：

在pom文件中引入的依赖是5的版本

<!-- MySQL数据库连接驱动 -->
<dependency>
  <groupId>mysql</groupId>
  <artifactId>mysql-connector-java</artifactId>
  <version>5.1.49</version>
</dependency>

注意applicationContext-datasource.xml中的driverClassName为com.mysql.cj.jdbc.Driver

<!-- 配置数据源 -->
<bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource">
    <property name="driverClassName" value="com.mysql.cj.jdbc.Driver"/>
    <property name="username" value="root"/>
    <property name="password" value="root"/>
    <property name="url" value="jdbc:mysql://127.0.0.1:3306/crm2008?useSSL=false&amp;useUnicode=true&amp;characterEncoding=UTF-8"/>
</bean>

事实上，如果你在pom中引入的是5的版本，那么driverClassName就应该写成com.mysql.jdbc.Driver。多写.cj就会报以上的错误！

同时，如果你在pom中引入是8的版本，那么在driverClassName里加不加cj都可以，或许是版本向下兼容了。