这个值为什么获取不到？

Question

 

 输入数据库中的用户名： 杨阳 ，密码：123 ，报的错是：在LoginController.java的判断没生效，获取不到值

java.lang.NullPointerException
	controller.LoginController.loginSuccess(LoginController.java:57)
	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:221)
	org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:136)
	org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:110)
	org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:817)
	org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:731)
	org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:85)
	org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:959)
	org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:893)
	org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:968)
	org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:870)
	javax.servlet.http.HttpServlet.service(HttpServlet.java:661)
	org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:844)
	javax.servlet.http.HttpServlet.service(HttpServlet.java:742)
	org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
	org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:121)
	org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
	org.springframework.web.filter.HiddenHttpMethodFilter.doFilterInternal(HiddenHttpMethodFilter.java:77)
	org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)

 LoginController.java

UserService.java 

 

UserServiceI.java

UserMapper.xml

 

我想实现在LoginController.java中判断输入的用户类型（user_type） ,然后跳转到不同的页面。

Answer 1

逐步排查：

1.userService是不是空的

2.username是什么？

3. find之后的user是什么？

按照日志来看，userService是空的