在学习mybatis的过程中，发现了很多错误，这里记录一下，以供后来使用
1，config.xml文件中配置项的顺序：
org.apache.ibatis.exceptions.PersistenceException: ### Error building SqlSession. ### Cause: org.apache.ibatis.builder.BuilderException: Error creating document instance. Cause: org.xml.sax.SAXParseException; lineNumber: 45; columnNumber: 17; 元素类型为 "configuration" 的内容必须匹配 "(properties?,settings?,typeAliases?,typeHandlers?,objectFactory?,objectWrapperFactory?,plugins?,environments?,databaseIdProvider?,mappers?)"。
错误原因：
properties/settings/typeAliases/typeHandlers/objectFactory/objectWrapperFactory/plugins/environments/databaseIdProvider/mappers