org.xml.sax.SAXParseException : Content is not allowed in prolog - mybatis

Question

This is my project demo, I want to use MyBatis xml configuration. But I got a SAXParseException error, like this
Caused by: org.apache.ibatis.builder.BuilderException: Error creating document instance. Cause: org.xml.sax.SAXParseException; lineNumber: 1; columnNumber: 1; Content is not allowed in prolog.
at org.apache.ibatis.parsing.XPathParser.createDocument(XPathParser.java:260)
at org.apache.ibatis.parsing.XPathParser.<init>(XPathParser.java:126)
at org.apache.ibatis.builder.xml.XMLMapperBuilder.<init>(XMLMapperBuilder.java:80)
at org.mybatis.spring.SqlSessionFactoryBean.buildSqlSessionFactory(SqlSessionFactoryBean.java:519)
... 56 more
Caused by: org.xml.sax.SAXParseException; lineNumber: 1; columnNumber: 1; Content is not allowed in prolog.
at com.sun.org.apache.xerces.internal.util.ErrorHandlerWrapper.createSAXParseException(ErrorHandlerWrapper.java:203)
at com.sun.org.apache.xerces.internal.util.ErrorHandlerWrapper.fatalError(ErrorHandlerWrapper.java:177)
at com.sun.org.apache.xerces.internal.impl.XMLErrorReporter.reportError(XMLErrorReporter.java:400)
at com.sun.org.apache.xerces.internal.impl.XMLErrorReporter.reportError(XMLErrorReporter.java:327)
at com.sun.org.apache.xerces.internal.impl.XMLScanner.reportFatalError(XMLScanner.java:1472)
at com.sun.org.apache.xerces.internal.impl.XMLDocumentScannerImpl$PrologDriver.next(XMLDocumentScannerImpl.java:994)
at com.sun.org.apache.xerces.internal.impl.XMLDocumentScannerImpl.next(XMLDocumentScannerImpl.java:602)
at com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl.scanDocument(XMLDocumentFragmentScannerImpl.java:505)
at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(XML11Configuration.java:842)
at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(XML11Configuration.java:771)
at com.sun.org.apache.xerces.internal.parsers.XMLParser.parse(XMLParser.java:141)
at com.sun.org.apache.xerces.internal.parsers.DOMParser.parse(DOMParser.java:243)
at com.sun.org.apache.xerces.internal.jaxp.DocumentBuilderImpl.parse(DocumentBuilderImpl.java:339)
at org.apache.ibatis.parsing.XPathParser.createDocument(XPathParser.java:258)
... 59 more
this is my mapper xml file:
<?xml version="1.0" encoding="UTF-8" ?>
<mapper namespace="com.ryanqy.mapper.UserMapper" xmlns="http://mybatis.org/schema/mybatis-mapper">
<resultMap id="userResultMap" type="com.ryanqy.entity.UserEntity">
<result column="username" property="username"/>
<result column="password" property="password"/>
</resultMap>
<select id="findUserByUserName" resultMap="userResultMap">
select * from uuc_user where username = #{userName}
</select>
</mapper>

Answer 1

Problem is with your mybatis config:
mybatis:
configuration:
map-underscore-to-camel-case: true
type-aliases-package: com.ryanqy.entity
mapper-locations: mapper
change mapper-locations to:
mapper-locations: mapper/UserMapper.xml
#OR
mapper-locations: mapper/*.xml
If you change, you receive error with missing DOCTYPE in your mapper XML, so add something like this
<!DOCTYPE mapper
PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-mapper.dtd">