MyBatis详细的执行流程

实例化 SqlSessionFactorySqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);// 实例化时，使用了上面读取的 mybatis-config 中的，存放于configuration 中 的配置参数 public SqlSessionFactory build(Configuration config) {    return new DefaultSqlSessionFactory(config);}public DefaultSqlSessionFactory(Configuration configuration) {    this.configuration = configuration;}

获取执行器类型configuration.getDefaultExecutorType()protected ExecutorType defaultExecutorType = ExecutorType.SIMPLE;默认是SIMPLE// 知识扩展mybatis提供三种sql执行器，分别是SIMPLE、REUSE、BATCH。SIMPLE 是默认执行器，根据对应的sql直接执行，不会做一些额外的操作。REUSE  是可重用执行器，重用对象是Statement（即该执行器会缓存同一个sql的Statement，省去Statement的重新创建，优化性能）（即会重用预处理语句）BATCH  执行器会重用预处理语句，并执行批量更新。SIMPLE、REUSE，可通过insert、update、delete方法的返回值判断sql是否执行成功，返回非0表示执行sql成功的条数，返回0表示sql执行失败BATCH，insert、update、delete方法返回值一直会是负数-2147482646，在该模式下insert、update、delete返回值将无任何意义，不能作为判断sql执行成功的判断依据

实例化 SqlSessionFactoryBuilder 构造器new SqlSessionFactoryBuilder();

获取 TransactionFactorytransactionFactory 是上面读取到的，存放在 configuration.getEnvironment(); 中的信息。mybatis-config 配置的是 JdbcTransactionFactory<transactionManager type=\"JDBC\"/>final TransactionFactory transactionFactory = getTransactionFactoryFromEnvironment(environment);private TransactionFactory getTransactionFactoryFromEnvironment(Environment environment) {    if (environment == null || environment.getTransactionFactory() == null) {      return new ManagedTransactionFactory();    }    return environment.getTransactionFactory();}

从 configuration 中获取 Environmentenvironment 信息是 上面从mybatis-config读取到的，存放在 configuration 中的信息。final Environment environment = configuration.getEnvironment();class Environment {    private final String id;    private final TransactionFactory transactionFactory;    private final DataSource dataSource;}

关闭 sqlSessionsqlSession.close()public void close() {    try {      executor.close(isCommitOrRollbackRequired(false));      closeCursors();      dirty = false;    } finally {      ErrorContext.instance().reset();   } }

通过 Resources 加载全局配置文件String resource = \"org/mybatis/example/mybatis-config.xml\

是

成功

提交事务sqlSession.commit()/**    * Flushes batch statements and commits database connection.   * @param force forces connection commit false   */public void commit(boolean force) {    try {      executor.commit(isCommitOrRollbackRequired(force));      dirty = false;    } catch (Exception e) {      throw ExceptionFactory.wrapException(\"Error committing transaction.  Cause: \

实现 CRUD

将xml配置文件中 <configuration></configuration> 标签中所有配置信息加载到到 Configuration 类中// 获取 mybatis-config.xml 文件中 <configuration></configuration>标签中的内容parseConfiguration(parser.evalNode(\"/configuration\"));// 将读出的各种类型的元素值，放入 configuration 中propertiesElement(root.evalNode(\"properties\"));Properties settings = settingsAsProperties(root.evalNode(\"settings\"));loadCustomVfs(settings);loadCustomLogImpl(settings);typeAliasesElement(root.evalNode(\"typeAliases\"));pluginElement(root.evalNode(\"plugins\"));objectFactoryElement(root.evalNode(\"objectFactory\"));objectWrapperFactoryElement(root.evalNode(\"objectWrapperFactory\"));reflectorFactoryElement(root.evalNode(\"reflectorFactory\"));settingsElement(settings);// read it after objectFactory and objectWrapperFactory issue #631environmentsElement(root.evalNode(\"environments\"));databaseIdProviderElement(root.evalNode(\"databaseIdProvider\"));typeHandlerElement(root.evalNode(\"typeHandlers\"));mapperElement(root.evalNode(\"mappers\"));

否