BUG—— Mybatis

Posted 2022-11-22 JohnnyLin00

ClassNotFoundException

### Error building SqlSession.
### The error may exist in com/johnny/entity/personMapper.xml
### Cause: org.apache.ibatis.builder.BuilderException: Error parsing SQL Mapper Configuration. Cause: org.apache.ibatis.builder.BuilderException: Error parsing Mapper XML. The XML location is 'com/johnny/entity/personMapper.xml'. Cause: org.apache.ibatis.builder.BuilderException: Error resolving class. Cause: org.apache.ibatis.type.TypeException: Could not resolve type alias 'Person'.  Cause: java.lang.ClassNotFoundException: Cannot find class: Person
	at org.apache.ibatis.exceptions.ExceptionFactory.wrapException(ExceptionFactory.java:30)

xml 类要限定全类名

<?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.johnny.personMapper">
	 <select id="selectPersonById" resultType="Person">
	 	select * from person where id = #id
	 </select>
</mapper>

正解

<?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.johnny.personMapper">
	 <select id="selectPersonById" resultType="com.johnny.entity.Person">
	 	select * from person where id = #id
	 </select>
</mapper>

xxxMapper is not known to the MapperRegistry.

Exception in thread "main" org.apache.ibatis.binding.BindingException: Type interface com.johnny.mapper.PersonMapper is not known to the MapperRegistry.
	at org.apache.ibatis.binding.MapperRegistry.getMapper(MapperRegistry.java:47)
	at org.apache.ibatis.session.Configuration.getMapper(Configuration.java:779)
	at org.apache.ibatis.session.defaults.DefaultSqlSession.getMapper(DefaultSqlSession.java:291)
	at com.johnny.test.TestMybatis.selectAllPerson(TestMybatis.java:36)
	at com.johnny.test.TestMybatis.main(TestMybatis.java:87)

将personMapper.xml

<?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.johnny.PersonMapper">  
	
	 <select id="selectPersonById" resultType="com.johnny.entity.Person">
	 	select * from person where id = #id
	 </select>
	 
	 <select id="selectAllPerson" resultType="com.johnny.entity.Person">
	 	select * from person 
	 </select>
	 
	 <insert id="addPerson" parameterType="com.johnny.entity.Person">
	 	insert into person(id, age, name)  values( #id, #age, #name)
	 </insert>
	 
	 <update id="updatePerson" parameterType ="com.johnny.entity.Person">
	 	update person set name = #name, age =#age where id = #id 
	 </update>
	 
	 <delete id="deletePersonById" parameterType ="int">
	 	delete from person where id=#id
	 </delete>
	 
	 
</mapper>

正解

<?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.johnny.mapper.PersonMapper">  <!-- 该mapper的命名空间要为对应接口的全类名 -->
	
	 <select id="selectPersonById" resultType="com.johnny.entity.Person">
	 	select * from person where id = #id
	 </select>
	 
	 <select id="selectAllPerson" resultType="com.johnny.entity.Person">
	 	select * from person 
	 </select>
	 
	 <insert id="addPerson" parameterType="com.johnny.entity.Person">
	 	insert into person(id, age, name)  values( #id, #age, #name)
	 </insert>
	 
	 <update id="updatePerson" parameterType ="com.johnny.entity.Person">
	 	update person set name = #name, age =#age where id = #id 
	 </update>
	 
	 <delete id="deletePersonById" parameterType ="int">
	 	delete from person where id=#id
	 </delete>
	 
	 
</mapper>

“configuration” 的内容必须匹配 “(properties?,settings?,typeAliases?,typeHandlers?,objectFactory?,objectWrapperFactory?,reflectorFactory?,plugins?,environments?,databaseIdProvider?,mappers?)”。

Exception in thread "main" org.apache.ibatis.exceptions.PersistenceException: 
### Error building SqlSession.
### Cause: org.apache.ibatis.builder.BuilderException: Error creating document instance.  Cause: org.xml.sax.SAXParseException; lineNumber: 58; columnNumber: 17; 元素类型为 "configuration" 的内容必须匹配 "(properties?,settings?,typeAliases?,typeHandlers?,objectFactory?,objectWrapperFactory?,reflectorFactory?,plugins?,environments?,databaseIdProvider?,mappers?)"。
	at org.apache.ibatis.exceptions.ExceptionFactory.wrapException(ExceptionFactory.java:30)
	at org.apache.ibatis.session.SqlSessionFactoryBuilder.build(SqlSessionFactoryBuilder.java:80)
	at org.apache.ibatis.session.SqlSessionFactoryBuilder.build(SqlSessionFactoryBuilder.java:64)
	at com.johnny.test.TestMybatis.queryNationByIdWithPerson(TestMybatis.java:72)
	at com.johnny.test.TestMybatis.main(TestMybatis.java:89)

按照提示

configuration标签下的子标签也有顺序的，必须按照以下顺序出现：
(properties?,settings?,typeAliases?,typeHandlers?,objectFactory?,objectWrapperFactory?,reflectorFactory?,plugins?,environments?,databaseIdProvider?,mappers?)"

开启了log4j日志， 控制台依然看不到日志输出

原因是：日志级别调为了ERRO ，只看得到ERRO及以上的错误信息。改成DEBUG即可
日志级别： DEBUG < INFO< WARN < ERRO

# Global logging configuration
log4j.rootLogger=DEBUG, stdout
# MyBatis logging configuration...
log4j.logger.org.mybatis.example.BlogMapper=TRACE
# Console output...
log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern=%5p [%t] - %m%n