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
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>druid</artifactId>
<version>1.1.10</version>
</dependency>
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=GMT spring.datasource.username=root spring.datasource.password=1234 spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver spring.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=5 spring.datasource.minIdle=5 spring.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=300000 spring.datasource.validationQuery=SELECT 1 FROM DUAL spring.datasource.testWhileIdle=true spring.datasource.testOnBorrow=false spring.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,wall spring.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
@Mapper
public 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
@Controller
public 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
@ConditionalOnMissingBean
public 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
@Configuration
public 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")
@SpringBootApplication
public 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
@Repository
public 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
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE configuration
PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
<settings>
<setting name="mapUnderscoreToCamelCase" value="true"/>
</settings>
</configuration>
EmployeeMapper.xml
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.cr.mybatis.mapper.EmployeeMapper">
<select id="getById"
resultType="com.cr.mybatis.pojo.Employee">
SELECT * FROM employee WHERE id=#{id}
</select>
<insert id="insertEmp">
INSERT INTO employee(lastName,email,gender,d_id)
VALUES (#{lastName},#{email},#{gender},#{dId})
</insert>
</mapper>
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
@Controller
public 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：
原文地址：https://www.cnblogs.com/Mrchengs/p/10358025.html
时间： 2024-10-19 16:21:16