数据库for循环获取clob字段时报错：IO 错误: Bad packet type

前两天在做学生考场对照单得打印功能，里面要求每张对照单（即一张A4纸）中要放置30个学生名单。我们当时做的时候，为了数据库转移方便，把学生头像都专门存放到一张头像表里了。所以在做对照单打印查询的时候，需要先遍历考场号，每个考场号下要查询对应的30名学生的基本信息，其中就包括学生头像，而这头像存储的是clob类型的字段值。

本来很正常，之前做的也很正常，两层for循环就实现了。之前的是每页30名。

这次换成了每页至少45名。就因为每页多了这15名学生，导致每次查询数据库clob字段的头像查询报错，也有不报错的时候，但是大多数是报错的，这很尴尬啊。

报错内容如下：

2020-11-19 14:30:20.670  WARN 5772 --- [io-9906-exec-13] com.zaxxer.hikari.pool.ProxyConnection   : DatebookHikariCP - Connection oracle.jdbc.driver.T4CConnection@679baf7f marked as broken because of SQLSTATE(08006), ErrorCode(17002)

java.sql.SQLRecoverableException: IO 错误: Bad packet type
	at oracle.jdbc.driver.T4CPreparedStatement.fetch(T4CPreparedStatement.java:1091) ~[ojdbc6-11.2.0.jar:11.2.0.1.0]
	at oracle.jdbc.driver.OracleResultSetImpl.close_or_fetch_from_next(OracleResultSetImpl.java:369) ~[ojdbc6-11.2.0.jar:11.2.0.1.0]
	at oracle.jdbc.driver.OracleResultSetImpl.next(OracleResultSetImpl.java:273) ~[ojdbc6-11.2.0.jar:11.2.0.1.0]
	at com.zaxxer.hikari.pool.HikariProxyResultSet.next(HikariProxyResultSet.java) [HikariCP-2.7.9.jar:na]
	at sun.reflect.GeneratedMethodAccessor800.invoke(Unknown Source) ~[na:na]
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:45005) ~[na:1.8.0_141]
	at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_141]
	at org.apache.ibatis.logging.jdbc.ResultSetLogger.invoke(ResultSetLogger.java:68) [mybatis-3.4.6.jar:3.4.6]
	at com.sun.proxy.$Proxy371.next(Unknown Source) [na:na]
	at org.apache.ibatis.executor.resultset.DefaultResultSetHandler.handleRowValuesForSimpleResultMap(DefaultResultSetHandler.java:353) [mybatis-3.4.6.jar:3.4.6]
	at org.apache.ibatis.executor.resultset.DefaultResultSetHandler.handleRowValues(DefaultResultSetHandler.java:330) [mybatis-3.4.6.jar:3.4.6]
	at org.apache.ibatis.executor.resultset.DefaultResultSetHandler.handleResultSet(DefaultResultSetHandler.java:303) [mybatis-3.4.6.jar:3.4.6]
	at org.apache.ibatis.executor.resultset.DefaultResultSetHandler.handleResultSets(DefaultResultSetHandler.java:196) [mybatis-3.4.6.jar:3.4.6]
	at org.apache.ibatis.executor.statement.PreparedStatementHandler.query(PreparedStatementHandler.java:64) [mybatis-3.4.6.jar:3.4.6]
	at org.apache.ibatis.executor.statement.RoutingStatementHandler.query(RoutingStatementHandler.java:79) [mybatis-3.4.6.jar:3.4.6]
	at org.apache.ibatis.executor.SimpleExecutor.doQuery(SimpleExecutor.java:63) [mybatis-3.4.6.jar:3.4.6]
	at org.apache.ibatis.executor.BaseExecutor.queryFromDatabase(BaseExecutor.java:326) [mybatis-3.4.6.jar:3.4.6]
	at org.apache.ibatis.executor.BaseExecutor.query(BaseExecutor.java:156) [mybatis-3.4.6.jar:3.4.6]
	at org.apache.ibatis.executor.CachingExecutor.query(CachingExecutor.java:109) [mybatis-3.4.6.jar:3.4.6]
	at com.github.pagehelper.PageInterceptor.intercept(PageInterceptor.java:108) [pagehelper-5.1.8.jar:na]
	at org.apache.ibatis.plugin.Plugin.invoke(Plugin.java:61) [mybatis-3.4.6.jar:3.4.6]
	at com.sun.proxy.$Proxy369.query(Unknown Source) [na:na]
	at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:148) [mybatis-3.4.6.jar:3.4.6]
	at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:141) [mybatis-3.4.6.jar:3.4.6]
	at sun.reflect.GeneratedMethodAccessor789.invoke(Unknown Source) ~[na:na]
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:45005) ~[na:1.8.0_141]
	at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_141]
	at org.mybatis.spring.SqlSessionTemplate$SqlSessionInterceptor.invoke(SqlSessionTemplate.java:433) [mybatis-spring-1.3.2.jar:1.3.2]
	at com.sun.proxy.$Proxy139.selectList(Unknown Source) [na:na]
	at org.mybatis.spring.SqlSessionTemplate.selectList(SqlSessionTemplate.java:230) [mybatis-spring-1.3.2.jar:1.3.2]
	at org.apache.ibatis.binding.MapperMethod.executeForMany(MapperMethod.java:139) [mybatis-3.4.6.jar:3.4.6]
	at org.apache.ibatis.binding.MapperMethod.execute(MapperMethod.java:76) [mybatis-3.4.6.jar:3.4.6]
	at org.apache.ibatis.binding.MapperProxy.invoke(MapperProxy.java:59) [mybatis-3.4.6.jar:3.4.6]
	at com.sun.proxy.$Proxy199.queryXslistByQzh_word(Unknown Source) [na:na]
	at com.inco.project.dzxt.gly.msap.service.impl.MsapServiceImpl.queryXslistByQzh_word(MsapServiceImpl.java:71) [classes/:na]
	at com.inco.project.dzxt.gly.msap.controller.MsapController.dcWord(MsapController.java:97) [classes/:na]
	at com.inco.project.dzxt.gly.msap.controller.MsapController$$FastClassBySpringCGLIB$$7afe8d5b.invoke(<generated>) [classes/:na]
	at org.springframework.cglib.proxy.MethodProxy.invoke(MethodProxy.java:204) [spring-core-5.0.10.RELEASE.jar:5.0.10.RELEASE]
	at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.invokeJoinpoint(CglibAopProxy.java:746) [spring-aop-5.0.10.RELEASE.jar:5.0.10.RELEASE]
	at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:163) [spring-aop-5.0.10.RELEASE.jar:5.0.10.RELEASE]
	at org.springframework.aop.aspectj.MethodInvocationProceedingJoinPoint.proceed(MethodInvocationProceedingJoinPoint.java:100) [spring-aop-5.0.10.RELEASE.jar:5.0.10.RELEASE]
	at com.inco.core.aop.paramsfxj.ParamJxythAspect.dealSearchDate(ParamJxythAspect.java:71) [incoSpringBoot-0.0.1-SNAPSHOT.jar:na]
	at sun.reflect.GeneratedMethodAccessor773.invoke(Unknown Source) ~[na:na]
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:45005) ~[na:1.8.0_141]
	at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_141]
	at org.springframework.aop.aspectj.AbstractAspectJAdvice.invokeAdviceMethodWithGivenArgs(AbstractAspectJAdvice.java:644) [spring-aop-5.0.10.RELEASE.jar:5.0.10.RELEASE]
	at org.springframework.aop.aspectj.AbstractAspectJAdvice.invokeAdviceMethod(AbstractAspectJAdvice.java:633) [spring-aop-5.0.10.RELEASE.jar:5.0.10.RELEASE]
	at org.