一、异常描述

关于mybatis映射xml配置文件执行报“org.mybatis.spring.MyBatisSystemException: nested exception is org.apache.ibatis.builder.BuilderException: The expression 'datas' evaluated to a null value..Caused by: org.apache.ibatis.builder.BuilderException: The expression 'datas' evaluated to a null value.”错误异常，详细日志如下

[14:27:08.651] [ERROR] [<T=V0MN2AP210IIQCdX>]  ReportDataController:  ReportDataController-edit@b@org.mybatis.spring.MyBatisSystemException: nested exception is org.apache.ibatis.builder.BuilderException: The expression 'datas' evaluated to a null value.@b@	at org.mybatis.spring.MyBatisExceptionTranslator.translateExceptionIfPossible(MyBatisExceptionTranslator.java:76) ~[mybatis-spring-1.2.3-1.2.3.jar:1.2.3]@b@	at org.mybatis.spring.SqlSessionTemplate$SqlSessionInterceptor.invoke(SqlSessionTemplate.java:399) ~[mybatis-spring-1.2.3-1.2.3.jar:1.2.3]@b@	at com.sun.proxy.$Proxy37.insert(Unknown Source) ~[?:?]@b@	at org.mybatis.spring.SqlSessionTemplate.insert(SqlSessionTemplate.java:253) ~[mybatis-spring-1.2.3-1.2.3.jar:1.2.3]@b@	at org.apache.ibatis.binding.MapperMethod.execute(MapperMethod.java:52) ~[mybatis-3.3.0-3.3.0.jar:3.3.0]@b@	at org.apache.ibatis.binding.MapperProxy.invoke(MapperProxy.java:53) ~[mybatis-3.3.0-3.3.0.jar:3.3.0]@b@	at com.sun.proxy.$Proxy56.batchInsert(Unknown Source) ~[?:?]@b@	at com.xwood.pms.templet.service.impl.ReportDataConfServiceImpl.deleteBeforeInsert(ReportDataConfServiceImpl.java:37) ~[bin/:?]@b@	at com.xwood.pms.templet.web.controller.ReportDataController.edit(ReportDataController.java:168) [bin/:?]@b@	at com.xwood.pms.templet.web.controller.ReportDataController$$FastClassBySpringCGLIB$$acc8b017.invoke(<generated>) [spring-core-3.2.13.RELEASE-3.2.13.RELEASE.jar:?]@b@	at org.springframework.cglib.proxy.MethodProxy.invoke(MethodProxy.java:204) [spring-core-3.2.13.RELEASE-3.2.13.RELEASE.jar:3.2.13.RELEASE]@b@	at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.invokeJoinpoint(CglibAopProxy.java:700) [spring-aop-3.2.13.RELEASE-3.2.13.RELEASE.jar:3.2.13.RELEASE]@b@	at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:150) [spring-aop-3.2.13.RELEASE-3.2.13.RELEASE.jar:3.2.13.RELEASE]@b@	at org.springframework.aop.aspectj.MethodInvocationProceedingJoinPoint.proceed(MethodInvocationProceedingJoinPoint.java:91) [spring-aop-3.2.13.RELEASE-3.2.13.RELEASE.jar:3.2.13.RELEASE]@b@	at com.xwood.pms.templet.aop.LogAppendAdvice.logController(LogAppendAdvice.java:47) [bin/:?]@b@	at sun.reflect.GeneratedMethodAccessor74.invoke(Unknown Source) ~[?:?]@b@	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:1.8.0_11]@b@	at java.lang.reflect.Method.invoke(Method.java:483) ~[?:1.8.0_11]@b@	at org.springframework.aop.aspectj.AbstractAspectJAdvice.invokeAdviceMethodWithGivenArgs(AbstractAspectJAdvice.java:621) [spring-aop-3.2.13.RELEASE-3.2.13.RELEASE.jar:3.2.13.RELEASE]@b@	at org.springframework.aop.aspectj.AbstractAspectJAdvice.invokeAdviceMethod(AbstractAspectJAdvice.java:610) [spring-aop-3.2.13.RELEASE-3.2.13.RELEASE.jar:3.2.13.RELEASE]@b@	at org.springframework.aop.aspectj.AspectJAroundAdvice.invoke(AspectJAroundAdvice.java:65) [spring-aop-3.2.13.RELEASE-3.2.13.RELEASE.jar:3.2.13.RELEASE]@b@	at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172) [spring-aop-3.2.13.RELEASE-3.2.13.RELEASE.jar:3.2.13.RELEASE]@b@	at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:91) [spring-aop-3.2.13.RELEASE-3.2.13.RELEASE.jar:3.2.13.RELEASE]@b@	at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172) [spring-aop-3.2.13.RELEASE-3.2.13.RELEASE.jar:3.2.13.RELEASE]@b@	at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:633) [spring-aop-3.2.13.RELEASE-3.2.13.RELEASE.jar:3.2.13.RELEASE]@b@	at com.xwood.pms.templet.web.controller.ReportDataController$$EnhancerBySpringCGLIB$$a23d0713.edit(<generated>) [spring-core-3.2.13.RELEASE-3.2.13.RELEASE.jar:?]@b@	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:1.8.0_11]@b@	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[?:1.8.0_11]@b@	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:1.8.0_11]@b@	at java.lang.reflect.Method.invoke(Method.java:483) ~[?:1.8.0_11]@b@	at org.springframework.web.method.support.InvocableHandlerMethod.invoke(InvocableHandlerMethod.java:215) [spring-web-3.2.13.RELEASE-3.2.13.RELEASE.jar:3.2.13.RELEASE]@b@	at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:132) [spring-web-3.2.13.RELEASE-3.2.13.RELEASE.jar:3.2.13.RELEASE]@b@	at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:104) [spring-webmvc-3.2.13.RELEASE-3.2.13.RELEASE.jar:3.2.13.RELEASE]@b@	at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandleMethod(RequestMappingHandlerAdapter.java:743) [spring-webmvc-3.2.13.RELEASE-3.2.13.RELEASE.jar:3.2.13.RELEASE]@b@	at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:672) [spring-webmvc-3.2.13.RELEASE-3.2.13.RELEASE.jar:3.2.13.RELEASE]@b@	at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:82) [spring-webmvc-3.2.13.RELEASE-3.2.13.RELEASE.jar:3.2.13.RELEASE]@b@	at com.xwood.sbase.web.DefWebRequestHandler.handleRequest(DefWebRequestHandler.java:61) [sbase-5.2.6.jar:5.2.6]@b@	at com.xwood.sbase.web.filter.DefaultFilterChain.doFinal(DefaultFilterChain.java:64) [sbase-5.2.6.jar:5.2.6]@b@	at com.xwood.sbase.web.filter.DefaultFilterChain.doFilter(DefaultFilterChain.java:57) [sbase-5.2.6.jar:5.2.6]@b@	at com.xwood.pms.templet.common.filter.XssSecurityFilter.doFilter(XssSecurityFilter.java:50) [bin/:?]@b@	at com.xwood.sbase.web.filter.DefaultFilterChain.doFilter(DefaultFilterChain.java:52) [sbase-5.2.6.jar:5.2.6]@b@	at com.xwood.sbase.web.filter.impl.PostJsonToFormFilter.doFilter(PostJsonToFormFilter.java:38) [sbase-5.2.6.jar:5.2.6]@b@	at com.xwood.sbase.web.filter.DefaultFilterChain.doFilter(DefaultFilterChain.java:52) [sbase-5.2.6.jar:5.2.6]@b@	at com.xwood.sbase.web.filter.impl.FileUploadFilter.doFilter(FileUploadFilter.java:40) [sbase-5.2.6.jar:5.2.6]@b@	at com.xwood.sbase.web.filter.DefaultFilterChain.doFilter(DefaultFilterChain.java:52) [sbase-5.2.6.jar:5.2.6]@b@	at com.xwood.sbase.web.DefWebDispatcher.handleRequest(DefWebDispatcher.java:134) [sbase-5.2.6.jar:5.2.6]@b@	at com.xwood.sbase.sar.SARContextBean.handleWebRequest(SARContextBean.java:170) [sbase-5.2.6.jar:5.2.6]@b@	at com.xwood.sbase.web.PAppWebRequestHandler.handleRequest(PAppWebRequestHandler.java:44) [sbase-5.2.6.jar:5.2.6]@b@	at com.xwood.sbase.web.filter.DefaultFilterChain.doFinal(DefaultFilterChain.java:64) [sbase-5.2.6.jar:5.2.6]@b@	at com.xwood.sbase.web.filter.DefaultFilterChain.doFilter(DefaultFilterChain.java:57) [sbase-5.2.6.jar:5.2.6]@b@	at com.xwood.sbase.web.filter.impl.CommonWebFilter.doFilter(CommonWebFilter.java:46) [sbase-5.2.6.jar:5.2.6]@b@	at com.xwood.sbase.web.filter.DefaultFilterChain.doFilter(DefaultFilterChain.java:52) [sbase-5.2.6.jar:5.2.6]@b@	at com.xwood.sbase.web.DefPAppWebDispatcher.dispatch(DefPAppWebDispatcher.java:80) [sbase-5.2.6.jar:5.2.6]@b@	at com.xwood.sbase.PAppContextBean.handleWebRequest(PAppContextBean.java:182) [sbase-5.2.6.jar:5.2.6]@b@	at com.xwood.sbase.protocol.web.PappServlet.service(PappServlet.java:63) [sbase-5.2.6.jar:5.2.6]@b@	at org.eclipse.jetty.servlet.ServletHolder.handle(ServletHolder.java:684) [jetty-servlet-8.1.16.v20140903-8.1.16.jar:8.1.16.v20140903]@b@	at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1496) [jetty-servlet-8.1.16.v20140903-8.1.16.jar:8.1.16.v20140903]@b@	at com.xwood.sbase.protocol.jetty.JettyResourceFilter.doFilter(JettyResourceFilter.java:73) [sbase-5.2.6.jar:5.2.6]@b@	at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1467) [jetty-servlet-8.1.16.v20140903-8.1.16.jar:8.1.16.v20140903]@b@	at org.eclipse.jetty.servlet.ServletHandler.doHandle(ServletHandler.java:501) [jetty-servlet-8.1.16.v20140903-8.1.16.jar:8.1.16.v20140903]@b@	at org.eclipse.jetty.server.session.SessionHandler.doHandle(SessionHandler.java:229) [jetty-server-8.1.16.v20140903-8.1.16.jar:8.1.16.v20140903]@b@	at org.eclipse.jetty.server.handler.ContextHandler.doHandle(ContextHandler.java:1086) [jetty-server-8.1.16.v20140903-8.1.16.jar:8.1.16.v20140903]@b@	at org.eclipse.jetty.servlet.ServletHandler.doScope(ServletHandler.java:429) [jetty-servlet-8.1.16.v20140903-8.1.16.jar:8.1.16.v20140903]@b@	at org.eclipse.jetty.server.session.SessionHandler.doScope(SessionHandler.java:193) [jetty-server-8.1.16.v20140903-8.1.16.jar:8.1.16.v20140903]@b@	at org.eclipse.jetty.server.handler.ContextHandler.doScope(ContextHandler.java:1020) [jetty-server-8.1.16.v20140903-8.1.16.jar:8.1.16.v20140903]@b@	at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:135) [jetty-server-8.1.16.v20140903-8.1.16.jar:8.1.16.v20140903]@b@	at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:116) [jetty-server-8.1.16.v20140903-8.1.16.jar:8.1.16.v20140903]@b@	at org.eclipse.jetty.server.Server.handle(Server.java:370) [jetty-server-8.1.16.v20140903-8.1.16.jar:8.1.16.v20140903]@b@	at org.eclipse.jetty.server.AbstractHttpConnection.handleRequest(AbstractHttpConnection.java:494) [jetty-server-8.1.16.v20140903-8.1.16.jar:8.1.16.v20140903]@b@	at org.eclipse.jetty.server.AbstractHttpConnection.content(AbstractHttpConnection.java:982) [jetty-server-8.1.16.v20140903-8.1.16.jar:8.1.16.v20140903]@b@	at org.eclipse.jetty.server.AbstractHttpConnection$RequestHandler.content(AbstractHttpConnection.java:1043) [jetty-server-8.1.16.v20140903-8.1.16.jar:8.1.16.v20140903]@b@	at org.eclipse.jetty.http.HttpParser.parseNext(HttpParser.java:865) [jetty-http-8.1.16.v20140903-8.1.16.jar:8.1.16.v20140903]@b@	at org.eclipse.jetty.http.HttpParser.parseAvailable(HttpParser.java:240) [jetty-http-8.1.16.v20140903-8.1.16.jar:8.1.16.v20140903]@b@	at org.eclipse.jetty.server.AsyncHttpConnection.handle(AsyncHttpConnection.java:82) [jetty-server-8.1.16.v20140903-8.1.16.jar:8.1.16.v20140903]@b@	at org.eclipse.jetty.io.nio.SelectChannelEndPoint.handle(SelectChannelEndPoint.java:696) [jetty-io-8.1.16.v20140903-8.1.16.jar:8.1.16.v20140903]@b@	at org.eclipse.jetty.io.nio.SelectChannelEndPoint$1.run(SelectChannelEndPoint.java:53) [jetty-io-8.1.16.v20140903-8.1.16.jar:8.1.16.v20140903]@b@	at org.eclipse.jetty.util.thread.QueuedThreadPool.runJob(QueuedThreadPool.java:608) [jetty-util-8.1.16.v20140903-8.1.16.jar:8.1.16.v20140903]@b@	at org.eclipse.jetty.util.thread.QueuedThreadPool$3.run(QueuedThreadPool.java:543) [jetty-util-8.1.16.v20140903-8.1.16.jar:8.1.16.v20140903]@b@	at java.lang.Thread.run(Thread.java:745) [?:1.8.0_11]@b@Caused by: org.apache.ibatis.builder.BuilderException: The expression 'datas' evaluated to a null value.@b@	at org.apache.ibatis.scripting.xmltags.ExpressionEvaluator.evaluateIterable(ExpressionEvaluator.java:45) ~[mybatis-3.3.0-3.3.0.jar:3.3.0]@b@	at org.apache.ibatis.scripting.xmltags.ForEachSqlNode.apply(ForEachSqlNode.java:55) ~[mybatis-3.3.0-3.3.0.jar:3.3.0]@b@	at org.apache.ibatis.scripting.xmltags.MixedSqlNode.apply(MixedSqlNode.java:33) ~[mybatis-3.3.0-3.3.0.jar:3.3.0]@b@	at org.apache.ibatis.scripting.xmltags.DynamicSqlSource.getBoundSql(DynamicSqlSource.java:41) ~[mybatis-3.3.0-3.3.0.jar:3.3.0]@b@	at org.apache.ibatis.mapping.MappedStatement.getBoundSql(MappedStatement.java:280) ~[mybatis-3.3.0-3.3.0.jar:3.3.0]@b@	at org.apache.ibatis.executor.statement.BaseStatementHandler.<init>(BaseStatementHandler.java:64) ~[mybatis-3.3.0-3.3.0.jar:3.3.0]@b@	at org.apache.ibatis.executor.statement.PreparedStatementHandler.<init>(PreparedStatementHandler.java:39) ~[mybatis-3.3.0-3.3.0.jar:3.3.0]@b@	at org.apache.ibatis.executor.statement.RoutingStatementHandler.<init>(RoutingStatementHandler.java:45) ~[mybatis-3.3.0-3.3.0.jar:3.3.0]@b@	at org.apache.ibatis.session.Configuration.newStatementHandler(Configuration.java:488) ~[mybatis-3.3.0-3.3.0.jar:3.3.0]@b@	at org.apache.ibatis.executor.SimpleExecutor.doUpdate(SimpleExecutor.java:47) ~[mybatis-3.3.0-3.3.0.jar:3.3.0]@b@	at org.apache.ibatis.executor.BaseExecutor.update(BaseExecutor.java:115) ~[mybatis-3.3.0-3.3.0.jar:3.3.0]@b@	at org.apache.ibatis.executor.CachingExecutor.update(CachingExecutor.java:75) ~[mybatis-3.3.0-3.3.0.jar:3.3.0]@b@	at org.apache.ibatis.session.defaults.DefaultSqlSession.update(DefaultSqlSession.java:170) ~[mybatis-3.3.0-3.3.0.jar:3.3.0]@b@	at org.apache.ibatis.session.defaults.DefaultSqlSession.insert(DefaultSqlSession.java:157) ~[mybatis-3.3.0-3.3.0.jar:3.3.0]@b@	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:1.8.0_11]@b@	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[?:1.8.0_11]@b@	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:1.8.0_11]@b@	at java.lang.reflect.Method.invoke(Method.java:483) ~[?:1.8.0_11]@b@	at org.mybatis.spring.SqlSessionTemplate$SqlSessionInterceptor.invoke(SqlSessionTemplate.java:386) ~[mybatis-spring-1.2.3-1.2.3.jar:1.2.3]@b@	... 77 more

二、解决方法

1. 原来xml配置如下

<?xml version="1.0" encoding="UTF-8" ?>  @b@<!DOCTYPE mapper   @b@  PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"   @b@  "http://mybatis.org/dtd/mybatis-3-mapper.dtd">@b@<mapper namespace="com.xwood.soofa.data.dao.ReportDataDAO"> @b@	@b@	<!-- 批量新增 -->@b@	<insert id="batchInsert" parameterType="ccom.xwood.soofa.data.dto.ReportDataDTO">@b@         INSERT INTO report_master@b@		   (ID, @b@			FIELD_TYPE,@b@			FIELD_NAME, @b@			STATUS,@b@			CREATED_BY,@b@			CREATED_DATE,@b@			UPDATED_BY,@b@			UPDATED_DATE,@b@			ORD_NUM)@b@		SELECT report_data_seq.nextval id,@b@				c.plateId,@b@				c.fieldType,@b@				c.fieldName,@b@				c.kpiId,@b@				c.status,@b@				c.createdBy,@b@				c.createdDate,@b@				c.updatedBy,@b@				c.updatedDate,@b@				c.ordNum@b@		 FROM ( <foreach  collection="datas"  separator="union all"@b@				item="repdata" index="index" >@b@					select @b@						#{repdata.fieldType,jdbcType=VARCHAR} fieldType, @b@						'Y' status,@b@						#{repdata.createdBy,jdbcType=VARCHAR} createdBy,@b@						systimestamp createdDate,@b@						#{repdata.updatedBy,jdbcType=VARCHAR} updatedBy,@b@						systimestamp updatedDate,@b@						#{repdata.ordNum,jdbcType=VARCHAR} ordNum@b@					from dual@b@			 </foreach>) c@b@    </insert> @b@	 @b@</mapper>

2. ReportDataServiceImpl服务实现类中批量插入batchInsert方法报错

@Service("reportDataService")@b@public class ReportDataServiceImpl implements ReportDataService {@b@	@b@	@b@	@Autowired@b@	private  ReportDataDAO  ReportDataDAO;@b@ @b@	 .. @b@	@Override@b@	public void batchInsert(ReportDataDTO dto) throws Exception {@b@		ReportDataDAO.batchInsert(dto);@b@	}@b@	@b@	@b@}

3. 由于没有判断dto的datas（List<ReportDataDTO>集合）为空情况，造成插入数据报上面异常错误，修改为下

@Service("reportDataService")@b@public class ReportDataServiceImpl implements ReportDataService {@b@	@b@	@b@	@Autowired@b@	private  ReportDataDAO  ReportDataDAO;@b@ @b@	 .. @b@	@Override@b@	public void batchInsert(ReportDataDTO dto) throws Exception {@b@		if(dto!=null&&CollectionUtils.isNotEmpty(dto.getDatas())){@b@		    ReportDataDAO.batchInsert(dto);@b@		}@b@	}@b@	@b@	@b@}