Caused by: org.apache.ibatis.exceptions.PersistenceException:

Error querying database. Cause: java.lang.NullPointerException

The error may exist in com/li/mapper/UserMapper.java (best guess)

The error may involve com.li.mapper.UserMapper.selectByPrimaryKey

The error occurred while executing a query

Cause: java.lang.NullPointerException

at org.apache.ibatis.exceptions.ExceptionFactory.wrapException(ExceptionFactory.java:30)
at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:150)
at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:141)
at org.apache.ibatis.session.defaults.DefaultSqlSession.selectOne(DefaultSqlSession.java:77)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.mybatis.spring.SqlSessionTemplate$SqlSessionInterceptor.invoke(SqlSessionTemplate.java:433)
... 36 more

Caused by: java.lang.NullPointerException
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:314)
at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
at com.alibaba.druid.util.JdbcUtils.createDriver(JdbcUtils.java:581)
at com.alibaba.druid.pool.DruidDataSource.init(DruidDataSource.java:815)
at com.alibaba.druid.pool.DruidDataSource.getConnection(DruidDataSource.java:1221)
at com.alibaba.druid.pool.DruidDataSource.getConnection(DruidDataSource.java:1217)
at com.alibaba.druid.pool.DruidDataSource.getConnection(DruidDataSource.java:90)
at org.springframework.jdbc.datasource.DataSourceUtils.fetchConnection(DataSourceUtils.java:151)
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:82)
at org.mybatis.spring.transaction.SpringManagedTransaction.getConnection(SpringManagedTransaction.java:68)
at org.apache.ibatis.executor.BaseExecutor.getConnection(BaseExecutor.java:338)
at org.apache.ibatis.executor.SimpleExecutor.prepareStatement(SimpleExecutor.java:84)
at org.apache.ibatis.executor.SimpleExecutor.doQuery(SimpleExecutor.java:62)
at org.apache.ibatis.executor.BaseExecutor.queryFromDatabase(BaseExecutor.java:326)
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:83)
at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:148)
... 43 more

2018-12-03 15:30:48.374 INFO 5188 --- [ Thread-2] o.s.w.c.s.GenericWebApplicationContext : Closing org.springframework.web.context.support.GenericWebApplicationContext@4bff7da0: startup date [Mon Dec 03 15:30:37 CST 2018]; root of context hierarchy
2018-12-03 15:30:48.386 INFO 5188 --- [ Thread-2] com.alibaba.druid.pool.DruidDataSource : {dataSource-1} closed

Process finished with exit code -1