mybatis配置文件xxxx.xml中缺失返回类型的后果

下面是mybatis配置文件xxxx.xml缺失resultMap的错误：

严重: Servlet.service() for servlet [SpringMVC] in context with path [/ZHDM] threw exception [Request processing failed; nested exception is org.mybatis.spring.MyBatisSystemException: nested exception is org.apache.ibatis.executor.ExecutorException: A query was run and no Result Maps were found for the Mapped Statement 'com.zhdm.dao.IGroupChatMsgVDao.selectUnReadMsg'.  It's likely that neither a Result Type nor a Result Map was specified.] with root causeorg.apache.ibatis.executor.ExecutorException: A query was run and no Result Maps were found for the Mapped Statement 'com.zhdm.dao.IGroupChatMsgVDao.selectUnReadMsg'.  It's likely that neither a Result Type nor a Result Map was specified.at org.apache.ibatis.executor.resultset.DefaultResultSetHandler.validateResultMapsCount(DefaultResultSetHandler.java:224)at org.apache.ibatis.executor.resultset.DefaultResultSetHandler.handleResultSets(DefaultResultSetHandler.java:147)at org.apache.ibatis.executor.statement.PreparedStatementHandler.query(PreparedStatementHandler.java:60)at org.apache.ibatis.executor.statement.RoutingStatementHandler.query(RoutingStatementHandler.java:73)at org.apache.ibatis.executor.SimpleExecutor.doQuery(SimpleExecutor.java:60)at org.apache.ibatis.executor.BaseExecutor.queryFromDatabase(BaseExecutor.java:267)at org.apache.ibatis.executor.BaseExecutor.query(BaseExecutor.java:137)at org.apache.ibatis.executor.CachingExecutor.query(CachingExecutor.java:96)at org.apache.ibatis.executor.CachingExecutor.query(CachingExecutor.java:77)at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:108)at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:102)at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)at java.lang.reflect.Method.invoke(Method.java:606)at org.mybatis.spring.SqlSessionTemplate$SqlSessionInterceptor.invoke(SqlSessionTemplate.java:358)at com.sun.proxy.$Proxy13.selectList(Unknown Source)at org.mybatis.spring.SqlSessionTemplate.selectList(SqlSessionTemplate.java:198)at org.apache.ibatis.binding.MapperMethod.executeForMany(MapperMethod.java:119)at org.apache.ibatis.binding.MapperMethod.execute(MapperMethod.java:63)at org.apache.ibatis.binding.MapperProxy.invoke(MapperProxy.java:52)at com.sun.proxy.$Proxy50.selectUnReadMsg(Unknown Source)at com.zhdm.service.impl.GroupChatServiceImpl.findUnReadyMsg(GroupChatServiceImpl.java:21)at com.zhdm.controller.GroupChatController.getUnReadMsg(GroupChatController.java:23)at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)at java.lang.reflect.Method.invoke(Method.java:606)at org.springframework.web.method.support.InvocableHandlerMethod.invoke(InvocableHandlerMethod.java:215)at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:132)at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:104)at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandleMethod(RequestMappingHandlerAdapter.java:749)at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:690)at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:83)at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:945)at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:876)at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:961)at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:852)at javax.servlet.http.HttpServlet.service(HttpServlet.java:618)at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:837)at javax.servlet.http.HttpServlet.service(HttpServlet.java:725)at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:301)at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:88)at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:108)at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:219)at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:106)at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:503)at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:136)at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:74)at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:610)at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:88)at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:516)at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1015)at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:652)at org.apache.coyote.http11.Http11AprProtocol$Http11ConnectionHandler.process(Http11AprProtocol.java:277)at org.apache.tomcat.util.net.AprEndpoint$SocketProcessor.doRun(AprEndpoint.java:2451)at org.apache.tomcat.util.net.AprEndpoint$SocketProcessor.run(AprEndpoint.java:2440)at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)at java.lang.Thread.run(Thread.java:744)

正确的写法如下：

 <select id="selectUnReadMsg" resultMap="BaseResultMap" >  select  *  from table  where   </select>