101.Mybatis 编程使用流程

一、流程模板

        //1. 配置mybatis
        Configuration configuration = configuration();

        //2. 获取SqlSessionFactory
        SqlSessionFactory sessionFactory = new DefaultSqlSessionFactory(configuration);

        //3. 获取Session
        SqlSession sqlSession = sessionFactory.openSession(true);

        //4. 获取Mapper
        OrignUserMapper mapper = sqlSession.getMapper(OrignUserMapper.class);

三、代码实战

1. 建表结构

CREATE TABLE `user` (
    `id` bigint(20) NOT NULL COMMENT '主键ID',
    `name` varchar(30) COLLATE utf8mb4_bin DEFAULT NULL COMMENT '姓名',
    `age` int(11) DEFAULT NULL COMMENT '年龄',
    `email` varchar(50) COLLATE utf8mb4_bin DEFAULT NULL COMMENT '邮箱',
    PRIMARY KEY (`id`)
    ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin

2. Bean

@Data
public class User {
    private Long id;
    private String name;
    private Integer age;
    private String email;
}

3. Mapper代码

Mapper �接口绑定实现方式(三种)? 本例使用第二种。

• 1.通过 XML Mapper 里面写 SQL 来绑定。
• 2.通过注解绑定，就是在接口的方法上面加上 @Select、@Update、@Insert、@Delete 注解。
• 3.通过注解绑定，在接口的方法上面加上 @SelectProvider、@UpdateProvider、@InsertProvider、@DeleteProvider 注解，通过 Java 代码，生成对应的动态 SQL

public interface OrignUserMapper {

    @Select(" select name from user where id = #{l}  ")
    User selectById(long l);

    @Insert(" insert into `user_center`.`user` ( `id`,  `age`, `email`, `name`) values (#{id}, #{age}, #{email}, #{name}); ")
    long insert(User user);
}

4. 测试类

/**
 * @ClassName : MybatisTest
 * @Description : 手动获取mapper测试
 * @Author : hack2012
 * @Date: 2020-12-18 04:24
 */
public class MybatisTest {

    @Test
    public void testConnect(){
        //1. 配置mybatis
        Configuration configuration = configuration();

        //2. 获取SqlSessionFactory
        SqlSessionFactory sessionFactory = new DefaultSqlSessionFactory(configuration);

        //3. 获取Session
        SqlSession sqlSession = sessionFactory.openSession(true);

        //4. 获取Mapper
        OrignUserMapper mapper = sqlSession.getMapper(OrignUserMapper.class);


        long id = 2l;
        User user = new User();
        user.setId(id);
        user.setName("name1");
        user.setAge(20);
        user.setEmail("aaaa@aa.com");
        long insert = mapper.insert(user);
        System.out.println(insert);

        User user_new = mapper.selectById(id);
        System.out.println(user_new);
    }

    private Configuration configuration(){
        Configuration configuration = new Configuration();//new MybatisConfiguration();


        //1. 设置环境配置
        configuration.setEnvironment(getEnv());
        //2. 添加mapper映射
        configuration.addMapper(OrignUserMapper.class);

        //设置下划线转驼峰命名
//        configuration.setMapUnderscoreToCamelCase(true);

        return configuration;
    }

    //初始化环境配置
    public Environment getEnv(){
        TransactionFactory transFactory = new JdbcTransactionFactory();
        MysqlDataSource datasource = new MysqlDataSource();
        datasource.setUrl("jdbc:mysql://xxxxxxxx:13306/user_center?&useUnicode=true&characterEncoding=utf8&autoReconnect=true&failOverReadOnly=false");
        datasource.setUser("root");
        datasource.setPassword("xxxxxxxxxxxxxxx");
        return  new Environment("did", transFactory, datasource);
    }
}