使用MyBatis框架操作数据，在SpringBoot框架中集成MyBatis。 使用步骤如下：
1、准备好数据库
?serverTimezone=GMT
2、MyBatis起步依赖：完成MyBatis对象自动配置，对象放在容器中
创建模块的时候，需要勾选spring web、MyBatis Framework、MySQL Driver 这三个
pom.xml文件
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.7.5</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<groupId>com.cqjtu</groupId>
<artifactId>springbootsql</artifactId>
<version>0.0.1-SNAPSHOT</version>
<properties>
<java.version>1.8</java.version>
</properties>
<dependencies>
<!--web的起步依赖 -->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<!--mybatis的起步依赖 -->
<dependency>
<groupId>org.mybatis.spring.boot</groupId>
<artifactId>mybatis-spring-boot-starter</artifactId>
<version>2.2.2</version>
</dependency>
<!-- mysql驱动-->
<dependency>
<groupId>com.mysql</groupId>
<artifactId>mysql-connector-j</artifactId>
<scope>runtime</scope>
</dependency>
<!--测试要用到的-->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
</dependencies>
<build>
<!--resource插件，这个在创建好项目后要手动添加 -->
<resources>
<resource>
<directory>src/main/java</directory>
<includes>
<include>**/*.yml</include>
<include>**/*.xml</include> <!--代表所有目录下的.xml文件 -->
</includes>
<filtering>false</filtering>
</resource>
</resources>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
</project>3、创建实体类Student
对应数据库中的每一个
package com.cqjtu.model;
public class Student
{
// 所有属性名必须和数据库中的命名一样
private Integer id;
private String name;
private Integer age;
public Integer getId()
{
return id;
}
public void setId(Integer id)
{
this.id = id;
}
public String getName()
{
return name;
}
public void setName(String name)
{
this.name = name;
}
public Integer getAge()
{
return age;
}
public void setAge(Integer age)
{
this.age = age;
}
@Override
public String toString()
{
return "Student{" +
"id=" + id +
", name='" + name + '\'' +
", age=" + age +
'}';
}
}4、创建Dao接口StudentDao，创建一个查询学生的方法
package com.cqjtu.dao;
import com.cqjtu.model.Student;
import org.apache.ibatis.annotations.Mapper;
import org.apache.ibatis.annotations.Param;
//@Mapper // 告诉mybatis这是dao接口，创建此接口的代理对象，这里不用这种方式
public interface StudentDao
{
// Param注解就是给SQL语句中的参数赋值
// 当外部要获取传给 id 的值时，只需要写 studId
Student selectById(@Param("stuId")Integer id);
}5、创建Dao接口对应的Mapper文件即.xml文件，用来写SQL语句
文件应该在同一个包下，且文件名应该一致
<?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">
<!--上面这些应该是固定的 -->
<!--namespace是StudentDao两个文件所在的位置 -->
<mapper namespace="com.cqjtu.dao.StudentDao">
<!--下面是SQL语句，id要和接口StudentDao中的查询方法名字一致 -->
<!--resultType是查询的返回结果类型，即Student类对象，要把他的位置写全 -->
<!--stuId就是@Param注解里的 -->
<select id="selectById" resultType="com.cqjtu.model.Student">
select id,name,age from student where id=#{stuId}
</select>
</mapper>6、创建Service层对象，创建StudentService接口和它的实现类StudentServiceImpl
接口
package com.cqjtu.service;
import com.cqjtu.model.Student;
public interface StudentService
{
Student queryStudent(Integer id);
}实现类
package com.cqjtu.service.impl;
import com.cqjtu.dao.StudentDao;
import com.cqjtu.service.StudentService;
import org.springframework.stereotype.Service;
import com.cqjtu.model.Student;
import javax.annotation.Resource;
@Service
public class StudentServiceImpl implements StudentService
{
@Resource // 自动注入
private StudentDao studentDao;
@Override
public Student queryStudent(Integer id)
{
return studentDao.selectById(id); // 调用查询方法
}
}7、创建Controller对象，访问Service
package com.cqjtu.controller;
import com.cqjtu.model.Student;
import com.cqjtu.service.StudentService;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;
import javax.annotation.Resource;
@Controller
public class StudentController
{
@Resource
private StudentService studentService;
@RequestMapping("/student/query")
@ResponseBody
public String queryStudent(Integer id)
{
Student student = studentService.queryStudent(id);
return student.toString();
}
}8、在application.yml文件中配置数据库的连接信息
// 配置端口号
server:
port: 9001
servlet:
context-path: /orm
spring:
datasource:
driver-class-name: com.mysql.cj.jdbc.Driver // 驱动
url: jdbc:mysql://localhost:3306/springdb //最后的springdb是要连接的数据库名
username: root //账号、密码别搞错了
password: 1234569、测试
注意MapperScan注解如果有多个Dao，就要重复写Mapper注解，而在Application类上面写一个MapperScan注解（参数是该Dao所在的包，可以写多个），就可以不用写Mapper注解
package com.cqjtu;
import org.mybatis.spring.annotation.MapperScan;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
@SpringBootApplication
@MapperScan(basePackages = "com.cqjtu.dao") // 使用了这个就不要在StudentDao接口中写@Mapper
public class Application
{
public static void main(String[] args)
{
SpringApplication.run(Application.class, args);
}
}运行程序成功后，在浏览器地址栏输入http://localhost:9001/orm/student/query?id=3就可以查询到
参数id可以换
