It's likely that neither a Result Type nor a Result Map was specified

1、错误描述

 2017-08-29 14:30:49,951 [http-bio-8888-exec-2] ERROR [core.security.process.exception.ExceptionResolverCustom] - nested exception is org.apache.ibatis.executor.ExecutorException: A query was run and no Result Maps were found for the Mapped Statement 'StudentMapper.count'.  It's likely that neither a Result Type nor a Result Map was specified.
  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 'StudentMapper.count'.  It's likely that neither a Result Type nor a Result Map was specified.
	at org.mybatis.spring.MyBatisExceptionTranslator.translateExceptionIfPossible(MyBatisExceptionTranslator.java:73)
	at core.util.CustomSqlSessionTemplate$SqlSessionInterceptor.invoke(CustomSqlSessionTemplate.java:316)
	at com.sun.proxy.$Proxy85.selectOne(Unknown Source)
	at core.util.CustomSqlSessionTemplate.selectOne(CustomSqlSessionTemplate.java:121)
	at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:116)
	at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:436)
	at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1078)
	at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:625)
	at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:318)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
	at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
	at java.lang.Thread.run(Thread.java:748)
Caused by: org.apache.ibatis.executor.ExecutorException: A query was run and no Result Maps were found for the Mapped Statement 'StudentMapper.count'.  It's likely that neither a Result Type nor a Result Map was specified.
	at org.apache.ibatis.executor.resultset.FastResultSetHandler.validateResultMapsCount(FastResultSetHandler.java:182)
	at org.apache.ibatis.executor.resultset.FastResultSetHandler.handleResultSets(FastResultSetHandler.java:155)
	at org.apache.ibatis.executor.statement.PreparedStatementHandler.query(PreparedStatementHandler.java:57)
	at org.apache.ibatis.executor.statement.RoutingStatementHandler.query(RoutingStatementHandler.java:70)

2、错误原因

<select id="count" parameterType="student">
         select count(*) from t_student_info    
</select>

      Mybatis配置文件中没有返回类型参数

3、解决办法

     添加resultType参数值

 <select id="count" parameterType="student" resultType="count">
         select count(*) from t_student_info    
 </select>