MyBatis+mysql+text

记录一下这个bug,到现在还没有知道原因是什么。 我使用SpringMVC+Mybatis+Mysql， 定义了一个Model: Activity:

CREATE TABLE `tb_activity_info` ( `id` int(11) NOT NULL AUTO_INCREMENT, `type` varchar(32) COLLATE utf8mb4_unicode_ci DEFAULT NULL COMMENT '活动类型', `name` varchar(128) COLLATE utf8mb4_unicode_ci DEFAULT NULL COMMENT '活动名称', `topic` varchar(128) COLLATE utf8mb4_unicode_ci DEFAULT NULL COMMENT '活动主题', `created_by` varchar(32) COLLATE utf8mb4_unicode_ci DEFAULT NULL, `created_time` datetime DEFAULT NULL, `status` varchar(32) COLLATE utf8mb4_unicode_ci DEFAULT NULL COMMENT '状态:草稿,发布,待审核', `is_approved` varchar(1) COLLATE utf8mb4_unicode_ci DEFAULT NULL COMMENT '后台管理系统是否已经审批通过', `description` varchar(256) COLLATE utf8mb4_unicode_ci DEFAULT NULL COMMENT '活动描述', `people` int(11) DEFAULT NULL COMMENT '参与人数', `cover` varchar(128) COLLATE utf8mb4_unicode_ci DEFAULT NULL COMMENT '封面', `start_time` datetime DEFAULT NULL COMMENT '开始时间', `end_time` datetime DEFAULT NULL COMMENT '结束时间', `location` varchar(45) COLLATE utf8mb4_unicode_ci DEFAULT NULL COMMENT '活动地点', `association_id` int(11) DEFAULT NULL COMMENT '协会id', `visible` varchar(1) COLLATE utf8mb4_unicode_ci DEFAULT '1' COMMENT '是否对外可见', `content` text COLLATE utf8mb4_unicode_ci COMMENT '正文内容，html', PRIMARY KEY (`id`) ) ENGINE=InnoDB AUTO_INCREMENT=2 DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci COMMENT='活动/赛事表';

根据mybatis-generator生成的mapper.xml是这样子的：

<?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd"> <mapper namespace="com.unionapp.activity.dao.ActivityMapper"> <resultMap id="BaseResultMap" type="com.unionapp.activity.model.Activity"> <id column="id" jdbcType="INTEGER" property="id" /> <result column="type" jdbcType="VARCHAR" property="type" /> <result column="name" jdbcType="VARCHAR" property="name" /> <result column="topic" jdbcType="VARCHAR" property="topic" /> <result column="created_by" jdbcType="VARCHAR" property="createdBy" /> <result column="created_time" jdbcType="TIMESTAMP" property="createdTime" /> <result column="status" jdbcType="VARCHAR" property="status" /> <result column="is_approved" jdbcType="VARCHAR" property="isApproved" /> <result column="description" jdbcType="VARCHAR" property="description" /> <result column="people" jdbcType="INTEGER" property="people" /> <result column="cover" jdbcType="VARCHAR" property="cover" /> <result column="start_time" jdbcType="TIMESTAMP" property="startTime" /> <result column="end_time" jdbcType="TIMESTAMP" property="endTime" /> <result column="location" jdbcType="VARCHAR" property="location" /> <result column="association_id" jdbcType="INTEGER" property="associationId" /> <result column="visible" jdbcType="VARCHAR" property="visible" /> </resultMap> <resultMap extends="BaseResultMap" id="ResultMapWithBLOBs" type="com.unionapp.activity.model.Activity"> <result column="content" jdbcType="LONGVARCHAR" property="content" /> </resultMap> <sql id="Base_Column_List"> id, type, name, topic, created_by, created_time, status, is_approved, description, people, cover, start_time, end_time, location, association_id, visible </sql> <sql id="Blob_Column_List"> content </sql> <select id="selectByPrimaryKey" parameterType="java.lang.Integer" resultMap="ResultMapWithBLOBs"> select <include refid="Base_Column_List" /> , <include refid="Blob_Column_List" /> from tb_activity_info where id = #{id,jdbcType=INTEGER} </select> </mapper>

在数据库里，我有一条id=1的数据，但是数据的content为NULL，调用mapper.selectByPrimaryKey方法的时候，出现了NullPointException, 而这个Exception并没有发生在我的逻辑代码里，而是在mybatis的框架发生的。如果把content置为非NULL，就不会出现报错。至今未解。：

Caused by: org.apache.ibatis.exceptions.PersistenceException: ### Error querying database. Cause: java.lang.NullPointerException ### The error may exist in file [E:\Project\IDEA\Union_App\UnionApp\target\UnionApp\WEB-INF\classes\com\unionapp\activity\mapper\ActivityMapper.xml] ### The error may involve com.unionapp.activity.dao.ActivityMapper.selectByPrimaryKey ### The error occurred while handling results ### SQL: select id, type, name, topic, created_by, created_time, status, is_approved, description, people, cover, start_time, end_time, location, association_id, visible , content from tb_activity_info where id = ? ### Cause: java.lang.NullPointerException at org.apache.ibatis.exceptions.ExceptionFactory.wrapException(ExceptionFactory.java:26) at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:111) at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:102) at org.apache.ibatis.session.defaults.DefaultSqlSession.selectOne(DefaultSqlSession.java:66) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:498) at org.mybatis.spring.SqlSessionTemplate$SqlSessionInterceptor.invoke(SqlSessionTemplate.java:358) ... 65 more Caused by: java.lang.NullPointerException at net.sf.log4jdbc.sql.resultsetcollector.DefaultResultSetCollector.methodReturned(DefaultResultSetCollector.java:204) at net.sf.log4jdbc.sql.jdbcapi.ResultSetSpy.reportAllReturns(ResultSetSpy.java:100) at net.sf.log4jdbc.sql.jdbcapi.ResultSetSpy.reportReturn(ResultSetSpy.java:192) at net.sf.log4jdbc.sql.jdbcapi.ResultSetSpy.wasNull(ResultSetSpy.java:2497) at com.mchange.v2.c3p0.impl.NewProxyResultSet.wasNull(NewProxyResultSet.java:259) at org.apache.ibatis.type.BaseTypeHandler.getResult(BaseTypeHandler.java:56) at org.apache.ibatis.executor.resultset.DefaultResultSetHandler.getPropertyMappingValue(DefaultResultSetHandler.java:393) at org.apache.ibatis.executor.resultset.DefaultResultSetHandler.applyPropertyMappings(DefaultResultSetHandler.java:367) at org.apache.ibatis.executor.resultset.DefaultResultSetHandler.getRowValue(DefaultResultSetHandler.java:341) at org.apache.ibatis.executor.resultset.DefaultResultSetHandler.handleRowValuesForSimpleResultMap(DefaultResultSetHandler.java:294) at org.apache.ibatis.executor.resultset.DefaultResultSetHandler.handleRowValues(DefaultResultSetHandler.java:269) at org.apache.ibatis.executor.resultset.DefaultResultSetHandler.handleResultSet(DefaultResultSetHandler.java:239) at org.apache.ibatis.executor.resultset.DefaultResultSetHandler.handleResultSets(DefaultResultSetHandler.java:153) 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) ... 72 more