MyBatis:The expression 'list' evaluated to a null value

完整错误信息：

严重: Servlet.service() for servlet [springmvc] in context with path [/xinghe-platform-web] threw exception [Request processing failed; nested exception is org.mybatis.spring.MyBatisSystemException: nested exception is org.apache.ibatis.builder.BuilderException: The expression ‘list‘ evaluated to a null value.] with root cause
org.apache.ibatis.builder.BuilderException: The expression ‘list‘ evaluated to a null value.
    at org.apache.ibatis.scripting.xmltags.ExpressionEvaluator.evaluateIterable(ExpressionEvaluator.java:40)
    at org.apache.ibatis.scripting.xmltags.ForEachSqlNode.apply(ForEachSqlNode.java:54)
    at org.apache.ibatis.scripting.xmltags.MixedSqlNode.apply(MixedSqlNode.java:32)
    at org.apache.ibatis.scripting.xmltags.DynamicSqlSource.getBoundSql(DynamicSqlSource.java:40)
    at org.apache.ibatis.mapping.MappedStatement.getBoundSql(MappedStatement.java:278)
    at org.apache.ibatis.executor.BaseExecutor.query(BaseExecutor.java:118)
    at sun.reflect.GeneratedMethodAccessor67.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
    at java.lang.reflect.Method.invoke(Unknown Source)
    at org.apache.ibatis.plugin.Invocation.proceed(Invocation.java:49)
    at com.xinghe.frame.mybatis.FlushCacheInterceptor.intercept(FlushCacheInterceptor.java:61)
    at org.apache.ibatis.plugin.Plugin.invoke(Plugin.java:60)
    at com.sun.proxy.$Proxy24.query(Unknown Source)
    at sun.reflect.GeneratedMethodAccessor67.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
    at java.lang.reflect.Method.invoke(Unknown Source)
    at org.apache.ibatis.plugin.Invocation.proceed(Invocation.java:49)
    at com.xinghe.frame.mybatis.OffsetLimitInterceptor.intercept(OffsetLimitInterceptor.java:55)
    at org.apache.ibatis.plugin.Plugin.invoke(Plugin.java:60)
    at com.sun.proxy.$Proxy24.query(Unknown Source)
    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.GeneratedMethodAccessor71.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
    at java.lang.reflect.Method.invoke(Unknown Source)
    at org.mybatis.spring.SqlSessionTemplate$SqlSessionInterceptor.invoke(SqlSessionTemplate.java:358)
    at com.sun.proxy.$Proxy17.selectList(Unknown Source)
    at org.mybatis.spring.SqlSessionTemplate.selectList(SqlSessionTemplate.java:198)
    at com.xinghe.platform.dao.ResScoreDao.getByResourceLocalId(ResScoreDao.java:43)
    at com.xinghe.platform.service.ResScoreManager.getByResourceLocalId(ResScoreManager.java:41)
    at com.xinghe.platform.service.ResScoreManager$$FastClassBySpringCGLIB$$68ba2513.invoke(<generated>)
    at org.springframework.cglib.proxy.MethodProxy.invoke(MethodProxy.java:204)
    at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.invokeJoinpoint(CglibAopProxy.java:717)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:157)
    at org.springframework.transaction.interceptor.TransactionInterceptor$1.proceedWithInvocation(TransactionInterceptor.java:99)
    at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:281)
    at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:96)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
    at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:653)
    at com.xinghe.platform.service.ResScoreManager$$EnhancerBySpringCGLIB$$9b94cd4.getByResourceLocalId(<generated>)
    at com.xinghe.platform.action.ResResourcePublic.getScore(ResResourcePublic.java:433)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
    at java.lang.reflect.Method.invoke(Unknown Source)
    at org.springframework.web.bind.annotation.support.HandlerMethodInvoker.invokeHandlerMethod(HandlerMethodInvoker.java:177)
    at org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter.invokeHandlerMethod(AnnotationMethodHandlerAdapter.java:446)
    at org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter.handle(AnnotationMethodHandlerAdapter.java:434)
    at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:943)
    at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:877)
    at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:966)
    at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:857)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:622)
    at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:842)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:291)
    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 com.auth.filter.AuthorizationFilter.doFilterInternal(AuthorizationFilter.java:77)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
    at org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:344)
    at org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:261)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
    at com.auth.filter.AuthenticationFilter.doFilterInternal(AuthenticationFilter.java:115)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
    at org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:344)
    at org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:261)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
    at com.xinghe.activate.filter.ActivateFilter.doFilterInternal(ActivateFilter.java:52)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
    at org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:344)
    at org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:261)
    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:107)
    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:502)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:142)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79)
    at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:617)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:88)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:518)
    at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1091)
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:668)
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1521)
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1478)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
    at java.lang.Thread.run(Unknown Source)

**环境：**Java项目，SpringMVC+MyBatis框架，

此错误的源码位置：

看到 MyBatisSystemException ，首先想到的是错误可能发生在ResScoreMapper.xml 文件中，但Dao层直接与Mapper.xml文件相关联，查看错误信息可以看到以下信息：

com.xinghe.platform.dao.ResScoreDao.getByResourceLocalId(ResScoreDao.java:43)

我遇到的这个错误就发生在这里！

错误原因：

说起错误原因，这里犯了一个小儿科的错误，从别的Dao文件中复制过来的代码，方法名改了，selectOne 中调用的Mapper中的命令空间及方法名忘记改了，所以导致此错误；

修正后如下：

由于 selectOne SQL返回多条记录时会出异常，所以这里改用：selectList 。

版权声明：本文为博主原创文章，未经博主允许不得转载。

MyBatis:The expression 'list' evaluated to a null value

时间： 2024-10-05 16:06:56

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