异常信息：

好家伙，这个错误让人毫无头绪。

异常详细信息：

根本原因。

java.lang.NoClassDefFoundError: net/sf/jsqlparser/expression/Expression
    com.github.pagehelper.PageHelper.setProperties(PageHelper.java:163)
    com.github.pagehelper.PageInterceptor.setProperties(PageInterceptor.java:181)
    com.github.pagehelper.PageInterceptor.checkDialectExists(PageInterceptor.java:130)
    com.github.pagehelper.PageInterceptor.intercept(PageInterceptor.java:89)
    org.apache.ibatis.plugin.Plugin.invoke(Plugin.java:57)
    com.sun.proxy.$Proxy34.query(Unknown Source)
    org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:104)
    org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:98)
    org.apache.ibatis.session.defaults.DefaultSqlSession.selectOne(DefaultSqlSession.java:62)
    sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    java.lang.reflect.Method.invoke(Method.java:498)
    org.mybatis.spring.SqlSessionTemplate$SqlSessionInterceptor.invoke(SqlSessionTemplate.java:433)
    com.sun.proxy.$Proxy18.selectOne(Unknown Source)
    org.mybatis.spring.SqlSessionTemplate.selectOne(SqlSessionTemplate.java:166)
    org.apache.ibatis.binding.MapperMethod.execute(MapperMethod.java:63)
    org.apache.ibatis.binding.MapperProxy.invoke(MapperProxy.java:43)
    com.sun.proxy.$Proxy21.getUserByAccount(Unknown Source)
    com.gy.gd.service.impl.UserServiceImpl.getUserByAccount(UserServiceImpl.java:32)
    com.gy.gd.controller.UserController.login(UserController.java:31)
    sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    java.lang.reflect.Method.invoke(Method.java:498)
    org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:205)
    org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:150)
    org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:117)
    org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:895)
    org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:808)
    org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87)
    org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1067)
    org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:963)
    org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1006)
    org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:909)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:681)
    org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:883)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:764)
    org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
    org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201)
    org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:117)

仔细看看就会发现它和它和它：

com.sun.proxy.$Proxy34.query(Unknown Source)

com.sun.proxy.$Proxy18.selectOne(Unknown Source)

com.sun.proxy.$Proxy21.getUserByAccount(Unknown Source)
    com.gy.gd.service.impl.UserServiceImpl.getUserByAccount(UserServiceImpl.java:32)
    com.gy.gd.controller.UserController.login(UserController.java:31)

给这三个信息编号1，2，3，然后就感觉是1引起2，2又引起3，所以问题可能还在mybatis。

正好前几天刚看过那个依赖的版本匹配问题，所以就改下依赖版本试试。

先上图：

然后去改一下pom，然后好了。