搭建环境：
1）、创建工程需要的maven坐标
这个mybatis的starter是mybatis官方出的适应springboot
2）、数据连接池的使用
引入Druid数据连接池
com.alibaba druid 1.1.10
3）、数据连接池的配置
配置文件的设置：
依然是Druid的配置
spring.datasource.url=jdbc:mysql://127.0.0.1:3306/users?serverTimezone=GMTspring.datasource.username=rootspring.datasource.password=1234spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driverspring.datasource.type=com.alibaba.druid.pool.DruidDataSource#其他配置# 下面为连接池的补充设置，应用到上面所有数据源中spring.datasource.initialSize=5spring.datasource.minIdle=5spring.datasource.maxActive=20# 配置获取连接等待超时的时间spring.datasource.maxWait=60000# 配置间隔多久才进行一次检测，检测需要关闭的空闲连接，单位是毫秒spring.datasource.timeBetweenEvictionRunsMillis=60000# 配置一个连接在池中最小生存的时间，单位是毫秒spring.datasource.minEvictableIdleTimeMillis=300000spring.datasource.validationQuery=SELECT 1 FROM DUALspring.datasource.testWhileIdle=truespring.datasource.testOnBorrow=falsespring.datasource.testOnReturn=false# 配置监控统计拦截的filters，去掉后监控界面sql无法统计，'wall'用于防火墙spring.datasource.filters=stat,wallspring.datasource.logSlowSql=true
4）、Druid的后台监控.......
5)、创建pojo类：
与数据库中的表对应
public class Employee { private Integer id; private String lastName; private Integer gender; private String email; private Integer dId;...} public class Department { private Integer id; private String departmentName;....} 
此时的基本环境已经搭建完成
使用MyBatis
1）、注解版：
mapper接口类
@Repository//指定这是一个操作数据库的mapper@Mapperpublic interface DepartMapper { @Select("select * from department where id=#{id}") public Department getDeptById(Integer id); @Delete("delete from department where id=#{id}") public int deleteDeptById(Integer id); @Insert("insert into department(departmentName) values(#{departmentName})") public int insertDept(Department department); @Update("update department set department_name=#{departmentName} where id=#{id}") public int updateDept(Department department);}
注解版本的都是用注解来进行标注，没有配置文件，所有的sql语句都在标签里面
controller类的实现方法：
@ResponseBody@Controllerpublic class DeptController { @Autowired DepartMapper departMapper; //模拟查询 @RequestMapping("/dept/{id}") public Department getDept(@PathVariable("id")Integer id){ Department dept = departMapper.getDeptById(id); return dept; } //模拟插入 @RequestMapping("/dept") public Department insertDept(Department department){ departMapper.insertDept(department); return department; }} 测试模拟插入：
测试查询：
在模拟插入的时候可以看到id为null，此时可以使用：
此时的自增主键也乐意被重新封装到对象中
//使用自动生成的组件@Options(useGeneratedKeys = true,keyProperty = "id")@Insert("insert into department(departmentName) values(#{departmentName})")public int insertDept(Department department); 
问题：
此时的数据表列值发生改变
@Select("select * from department where id=#{id}")public Department getDeptById(Integer id); 此时执行查询department_name是封装不到对象中的
@Bean@ConditionalOnMissingBeanpublic SqlSessionFactory sqlSessionFactory(DataSource dataSource) throws Exception { SqlSessionFactoryBean factory = new SqlSessionFactoryBean(); factory.setDataSource(dataSource); factory.setVfs(SpringBootVFS.class); if (StringUtils.hasText(this.properties.getConfigLocation())) { factory.setConfigLocation(this.resourceLoader.getResource(this.properties.getConfigLocation())); } org.apache.ibatis.session.Configuration configuration = this.properties.getConfiguration(); if (configuration == null && !StringUtils.hasText(this.properties.getConfigLocation())) { configuration = new org.apache.ibatis.session.Configuration(); } if (configuration != null && !CollectionUtils.isEmpty(this.configurationCustomizers)) { Iterator var4 = this.configurationCustomizers.iterator(); while(var4.hasNext()) { ConfigurationCustomizer customizer = (ConfigurationCustomizer)var4.next(); customizer.customize(configuration); } }......}
开启驼峰命名
自定义MyBatis的配置规则
@Configurationpublic class MyBatisConfig { @Bean public ConfigurationCustomizer configurationCustomizer(){ return new ConfigurationCustomizer() { @Override public void customize(org.apache.ibatis.session.Configuration configuration) { //开启驼峰命名发 configuration.setMapUnderscoreToCamelCase(true); } }; }} 此时可以封装到对象
关于mapper类特别多的情况：
如果mapper特别多的情况、每一个mapper类都是用@Mapper是极为麻烦的
此时可以使用 @MapperScan直接指定mapper的包，进行对mapper的类批量扫描
@MapperScan(value = "com.cr.mybatis.mapper")@SpringBootApplicationpublic class MybatisApplication { public static void main(String[] args) { SpringApplication.run(MybatisApplication.class, args); }}
2）、配置文件的方式
这里的mybatis知识就不再多说了 直接上代码
首先写接口mapper类：
EmployeeMapper.java
@Repositorypublic interface EmployeeMapper { public Employee getById(Integer id); public void insertEmp(Employee employee);}
注意：这里的mapper接口需要使用@Mapper/@MapperScan进行扫描
mybatis配置文件：
mybatis-config.xml
EmployeeMapper.xml
INSERT INTO employee(lastName,email,gender,d_id) VALUES (#{lastName},#{email},#{gender},#{dId})
工程配置文件
需要指定其配置问价的位置
#配置mybatis#mybatis的配置文件mybatis.config-location=classpath:mybatis/mybatis-config.xml#mapper的配置文件mybatis.mapper-locations=classpath:mybatis/mapper/*.xml
测试的controller类：
@ResponseBody@Controllerpublic class EmpTest { @Autowired EmployeeMapper employeeMapper; //查询 @RequestMapping("/emp/{id}") public Employee getEmp(@PathVariable("id") Integer id){ Employee emp = employeeMapper.getById(id); return emp; } @RequestMapping("/emp") public Employee insert(Employee employee){ employeeMapper.insertEmp(employee); return employee; }} 测试：
