Mybatis Learning Notes, introduction and Quick start
What is 1.MyBatis?
MyBatis is an excellent persistence layer framework that supports normal SQL queries, stored procedures, and high-level mapping. MyBatis eliminates almost all manual setting of JDBC code and parameters and retrieval encapsulation of the result set. MyBatis can use simple XML or annotations for configuration and raw mapping, mapping interfaces and Java's POJO (Plain Old Java Objects, plain Java objects) to records in the database. MyBatis allows programmers to focus on sql, through the mapping provided by MyBatis, free and flexible generation (semi-automatic, mostly requires programmers to write sql) to meet the needs of sql statements.
The frame structure of 2.MyBatis
Configuration file for 3.MyBatis
4. Mapping file
SELECT * FROM USER WHERE id=# {value} SELECT * FROM USER WHERE username LIKE'% ${value}% 'SELECT LAST_INSERT_ID () insert into user (username,birthday,sex,address) value (# {username}, # {birthday}, # {sex}, # {address}) delete from user where id=# {id} update user set username=# {username}, birthday=# {birthday}, sex=# {sex}, address=# {address} where id=# {id}
The properties of the pojo object are:
/ / the attribute name corresponds to the field of the database table
Private int id
Private String username;// user name
Private String sex;// gender
Private Date birthday;// 's birthday
Private String address;// address
/ / and the get,set method of the attribute
5. Usage
/ / mybatis configuration file String resource = "SqlMapConfig.xml"; / / get the profile flow InputStream inputStream = Resources.getResourceAsStream (resource); / / create a session factory and pass in the profile information of mybatis SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder (). Build (inputStream); / / get SqlSessionSqlSession sqlSession = sqlSessionFactory.openSession () through the factory / / manipulate the database through SqlSession / / the first parameter: map the id of statement in the file, equal to = namespace+ "." + the second parameter of id// of statement: specify the parameter of parameterType type matched in the mapping file / / sqlSession.selectOne result is an object of type resultType matching in the mapping file / / selectOne query a record User user = sqlSession.selectOne ("test.findUserById", 1); System.out.println (user) / / release resource sqlSession.close ()
