오류 - HTTP Status 500 - Request processing failed

오류내용

HTTP Status 500 - Request processing failed; nested exception is java.lang.NullPointerException

type Exception report

message Request processing failed; nested exception is java.lang.NullPointerException

description The server encountered an internal error that prevented it from fulfilling this request.

exception

org.springframework.web.util.NestedServletException: Request processing failed; nested exception is java.lang.NullPointerException
	org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:894)
	org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:778)
	javax.servlet.http.HttpServlet.service(HttpServlet.java:624)
	javax.servlet.http.HttpServlet.service(HttpServlet.java:731)
	org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
	org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:88)
	org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:76)

root cause

java.lang.NullPointerException
	com.dt.dao.MemberDao.list(MemberDao.java:36)
	com.dt.controller.MemberController.list(MemberController.java:25)
	sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
	sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
	java.lang.reflect.Method.invoke(Unknown Source)
	org.springframework.web.method.support.InvocableHandlerMethod.invoke(InvocableHandlerMethod.java:213)
	org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:126)
	org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:96)
	org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:617)
	org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:578)
	org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:80)
	org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:923)
	org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:852)
	org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:882)
	org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:778)
	javax.servlet.http.HttpServlet.service(HttpServlet.java:624)
	javax.servlet.http.HttpServlet.service(HttpServlet.java:731)
	org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
	org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:88)
	org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:76)

콘솔내용

MemberDao Error : org.apache.ibatis.exceptions.PersistenceException: 

### Error building SqlSession.

### The error may exist in com/dt/data/MapperMember.xml

### Cause: org.apache.ibatis.builder.BuilderException: Error parsing SQL Mapper Configuration. Cause: java.lang.RuntimeException: Error parsing Mapper XML. Cause: org.apache.ibatis.builder.BuilderException: Error resolving class . Cause: org.apache.ibatis.type.TypeException: Could not resolve type alias 'memberVo'.  Cause: java.lang.ClassNotFoundException: Cannot find class: memberVo

RestaurantDao Error : org.apache.ibatis.exceptions.PersistenceException: 

### Error building SqlSession.

### The error may exist in com/dt/data/MapperMember.xml

### Cause: org.apache.ibatis.builder.BuilderException: Error parsing SQL Mapper Configuration. Cause: java.lang.RuntimeException: Error parsing Mapper XML. Cause: org.apache.ibatis.builder.BuilderException: Error resolving class . Cause: org.apache.ibatis.type.TypeException: Could not resolve type alias 'memberVo'.  Cause: java.lang.ClassNotFoundException: Cannot find class: memberVo

INFO : org.springframework.web.servlet.DispatcherServlet - FrameworkServlet 'appServlet': initialization completed in 2152 ms

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해결방법

dbConfig.xml 부분에서 typeAliases 부분을 설정하지 않아서 생긴 오류

--------------------------------------------------------------------

<typeAliases>

<typeAlias type="com.dt.vo.MemberVo" alias="memberVo"/>

<typeAlias type="com.dt.vo.RestaurantVo" alias="restaurantVo"/>

</typeAliases>

--------------------------------------------------------------------

이처럼 추가해 주면 된다.

밑에 스크린샷은 순서대로 구성되어있다.

1,2 번은 오류내용, 콘솔내용이며

3,4 번은 해결 전 - 후 로 보면된다.