Mybatis操作主体流程

完整的时序图可以打开我的云笔记进行查看，对浏览器查看比例进行缩放为250%即可

1 Mybatis操作主体流程

定位配置文件的位置构建sessionFactory获取数据库操作会话建立数据库连接并执行数据库操作

1.1 定位配置文件位置

使用org.apache.ibatis.io.Resources.getResourceAsReader(String)定位mybatis配置文件的位置，获得文件的输入流。

Created with Raphaël 2.1.0ReaderReaderResourcesResourcesInputStreamReaderInputStreamReaderInputStreamInputStreamClassLoaderWrapperClassLoaderWrapperClassLoaderClassLoadergetResourceAsReader()getResourceAsReader()''getResourceAsStream()getResourceAsStream()getResourceAsStream()''getResourceAsReadernew InputStreamReader()

1.2构建SqlSessionFactory

构建SqlSessionFactory的时序图,使用SqlSessionFactoryBuilder创建SqlSessionFactory对象

Created with Raphaël 2.1.0SqlSessionFactoryBuilderSqlSessionFactoryBuilderXMLConfigBuilderXMLConfigBuilderXPathParserXPathParserDocumentBuilderDocumentBuilderDOMParserDOMParserDocumentDocumentConfigurationConfigurationSqlSessionFactorySqlSessionFactorybuild(reader)XMLConfigBuilder(XPathParser)createDocument()parse()getDocument()new XPathParser()new XMLConfigBuilder()parse()parseConfiguration()build(Configuration)

根据时序图可以看得出，创建sessionFactory需要

将读入的配置文件流解析为Document对象将Document对象解析为Configuration对象使用Configuration对象，通过build（）方法完成对SqlSessionFactory对象的创建。

1.3 获取数据库操作的会话

Created with Raphaël 2.1.0SqlSessionFactorySqlSessionFactoryDefaultSqlSessionFactoryDefaultSqlSessionFactorySqlSessionSqlSessionopenSession()openSessionFromDataSource()new DefaultSqlSession()

1.4 获取接口实例

Created with Raphaël 2.1.0SqlSessionSqlSessionDefaultSqlSessionDefaultSqlSessionConfigurationConfigurationMapperRegistryMapperRegistryProxyProxyUserMapperUserMappergetMapper()getMapper()getMapper()newInstance()Proxy.newProxyInstance() Created with Raphaël 2.1.0UserMapperUserMapperMapperProxyMapperProxyMapperMethodMapperMethodDefaultSqlSessionDefaultSqlSessionCachingExecutorCachingExecutorSimpleExecutorSimpleExecutorBaseExecutorBaseExecutorPreparedStatementHandlerPreparedStatementHandlerPreparedStatementPreparedStatementDefaultResultSetHandlerDefaultResultSetHandlergetUserById()execute()selectOne()selectList()query()query()queryFromDatabase()doQuery()prepareStatement()getConnection()prepare()query()execute()handleResultSets()''

在执行具体的 org.apache.ibatis.executor.SimpleExecutor.prepareStatement(StatementHandler, Log)处连接数据库，检查是否能连接成功

数据库连接时序图

Created with Raphaël 2.1.0SimpleExecutorSimpleExecutorBaseExecutorBaseExecutorJdbcTransactionJdbcTransactionDataSourceDataSourceUnpooledDataSourceUnpooledDataSourceDriverManagerDriverManagerDriverInfoDriverInfogetConnection()getConnection()getConnection()openConnection()getConnection()popConnection()new PooledConnection()doGetConnection()getConnection()connect()newInstance()''