Learn mybatis framework example tutorial

1. Introduction to Mybatis (mainly from the following two points)

1.MyBatis is an excellent persistence layer framework, which encapsulates the process of jdbc operating the database. So that developers only need to focus on SQL itself, without spending energy to deal with jdbc complicated process codes such as registering drivers, creating connections, creating statements, manually setting parameters, result set retrieval, etc..

2.Mybatis configures various statements (statement, preparedStatemnt, CallableStatement) to be executed through xml or annotations, and maps the java object and the sql in the statement to generate the final sql statement to be executed. Finally The mybatis framework executes sql and maps the results into java objects and returns them.

2. mybatis framework schematic diagram

3. Architecture flow chart and its explanation

1. mybatis Configuration

SqlMapConfig.xml, this file serves as the global configuration file of mybatis, and configures mybatis 's operating environment and other information. The

mapper.xml file is the sql mapping file. The sql for operating the database is configured in the file. statement. This file needs to be loaded in SqlMapConfig.xml.

2, Construct SqlSessionFactory through mybatis environment and other configuration information

3, Created by the session factory sqlSession is the session, and the database needs to be operated through sqlSession.

4. MybatisThe bottom layer is customized ExecutorThe executor interface operates the database, ExecutorThe interface has two implementations, one is the basic executor and the other is the cache executor.

5. Mapped Statement is also mybatis a bottom-level encapsulated object, which wraps mybatisConfiguration information and sql mapping information, etc. mapper.xml A sql in the file corresponds to a Mapped Statement object, The id of sql is the id## of Mapped statement #.

6. Mapped Statement

defines the sql execution input parameters, including HashMap , basic type, pojo, Executor through Mapped Statement in execution## Before #sql, map the input java object to sql. The input parameter mapping is jdbcSet parameters for preparedStatement in programming.

7. Mapped Statement Defines the execution output result of sql, including HashMap, basic type, pojo, Executor is executing sql# through Mapped Statement ##Then the output result is mapped to the java object. The output result mapping process is equivalent to mapping the result in jdbc programming analysis process.

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