报错如下

ERROR [main] - {dataSource-1} init error
java.sql.SQLException: ${jdbc.driver}
	at com.alibaba.druid.util.JdbcUtils.createDriver(JdbcUtils.java:689)
	at com.alibaba.druid.pool.DruidDataSource.resolveDriver(DruidDataSource.java:1219)
	at com.alibaba.druid.pool.DruidDataSource.init(DruidDataSource.java:888)
	at com.alibaba.druid.pool.DruidDataSource.getConnection(DruidDataSource.java:1403)
	at com.alibaba.druid.pool.DruidDataSource.getConnection(DruidDataSource.java:1399)
	at com.alibaba.druid.pool.DruidDataSource.getConnection(DruidDataSource.java:100)
	at org.springframework.jdbc.datasource.DataSourceUtils.fetchConnection(DataSourceUtils.java:157)
	at org.springframework.jdbc.datasource.DataSourceUtils.doGetConnection(DataSourceUtils.java:115)
	at org.springframework.jdbc.datasource.DataSourceUtils.getConnection(DataSourceUtils.java:78)
	at org.mybatis.spring.transaction.SpringManagedTransaction.openConnection(SpringManagedTransaction.java:80)
	at org.mybatis.spring.transaction.SpringManagedTransaction.getConnection(SpringManagedTransaction.java:67)
	at org.apache.ibatis.executor.BaseExecutor.getConnection(BaseExecutor.java:337)
	at org.apache.ibatis.executor.SimpleExecutor.prepareStatement(SimpleExecutor.java:86)
	at org.apache.ibatis.executor.SimpleExecutor.doQuery(SimpleExecutor.java:62)
	at org.apache.ibatis.executor.BaseExecutor.queryFromDatabase(BaseExecutor.java:325)
	at org.apache.ibatis.executor.BaseExecutor.query(BaseExecutor.java:156)
	at org.apache.ibatis.executor.CachingExecutor.query(CachingExecutor.java:109)
	at org.apache.ibatis.executor.CachingExecutor.query(CachingExecutor.java:89)
	at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:147)
	at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:140)
	at org.apache.ibatis.binding.MapperMethod.executeForMany(MapperMethod.java:147)
	at org.apache.ibatis.binding.MapperMethod.execute(MapperMethod.java:80)
	at org.apache.ibatis.binding.MapperProxy$PlainMethodInvoker.invoke(MapperProxy.java:152)
	at org.apache.ibatis.binding.MapperProxy.invoke(MapperProxy.java:85)
	at com.sun.proxy.$Proxy10.queryStudents(Unknown Source)
	at test.main(test.java:19)

1. database.properties没有问题

jdbc.driver=com.mysql.cj.jdbc.Driver
jdbc.url=jdbc:mysql://localhost:3306/ssmnew?useUnicode=true&characterEncoding=utf8&serverTimezone=GMT
jdbc.username=root
jdbc.password=123456
jdbc.init=1
jdbc.minIdle=1
jdbc.maxActive=20

里面的username的root后面不要有空格！！！ 这也可能导致报错，以前遇到过

还有最好加上时区

2. 考虑兼容问题：把数据库版本提高了,再次运行还是报错

<dependency>
   <groupId>mysql</groupId>
   <artifactId>mysql-connector-java</artifactId>
   <version>8.0.27</version>
</dependency

3.  把applicationContext.xml配置文件重新写了一遍运行成功了

发现只有一个id不一样，离谱啊

 所以SqlSessionFactoryBean的id不能是sqlSessionFactory吗？

反正id改为sessionFactory以后运行确实不报错了

这里怀疑是会和spring自带的配置发生冲突

 修改如下：

运行成功：

以下是完整代码

<?xml version="1.0" encoding="utf8" ?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:context="http://www.springframework.org/schema/context"
       xmlns:p="http://www.springframework.org/schema/p"
       xmlns:aop="http://www.springframework.org/schema/aop"
       xmlns:tx="http://www.springframework.org/schema/tx"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
                           http://www.springframework.org/schema/beans/spring-beans.xsd
                           http://www.springframework.org/schema/p
                           http://www.springframework.org/schema/p/spring-p.xsd
                           http://www.springframework.org/schema/aop
                           http://www.springframework.org/schema/aop/spring-aop.xsd
                           http://www.springframework.org/schema/tx
                           http://www.springframework.org/schema/tx/spring-tx.xsd
                           http://www.springframework.org/schema/context
                           http://www.springframework.org/schema/context/spring-context.xsd "
>
    <context:property-placeholder location="classpath:database.properties"/>
    <bean id="dataSource" class="com.alibaba.druid.pool.DruidDataSource">
        <property name="driverClassName" value="${jdbc.driver}"/>
        <property name="url" value="${jdbc.url}"/>
        <property name="username" value="${jdbc.username}"/>
        <property name="password" value="${jdbc.password}"/>
    </bean>
    <bean id="sessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
        <property name="dataSource" ref="dataSource"/>
        <property name="mapperLocations">
            <value>classpath:com/lyx/mapper/*.xml</value>
        </property>
        <property name="typeAliasesPackage" value="com.lyx.entity"/>
    </bean>
    <bean id="mapperScannerConfigurer" class="org.mybatis.spring.mapper.MapperScannerConfigurer">
        <property name="basePackage" value="com.lyx.mapper"/>
        <property name="sqlSessionFactoryBeanName" value="sessionFactory"/>
    </bean>
    <bean id="studentService" class="com.lyx.service.impl.StudentServiceImpl">
        <property name="studentMapper" ref="studentMapper"/>
    </bean>

</beans>