整合MyBatis

官方文档：http://mybatis.org/spring-boot-starter/mybatis-spring-boot-autoconfigure/

Maven仓库地址：https://mvnrepository.com/artifact/org.mybatis.spring.boot/mybatis-spring-boot-starter/2.1.1

整合测试

1、导入 MyBatis 所需要的依赖

<dependency>
    <groupId>org.mybatis.spring.boot</groupId>
    <artifactId>mybatis-spring-boot-starter</artifactId>
    <version>2.1.1</version>
</dependency>

2、配置数据库连接信息（不变）

spring:
  datasource:
    username: root
    password: 123456
    #?serverTimezone=UTC解决时区的报错
    url: jdbc:mysql://localhost:3306/springboot?serverTimezone=UTC&useUnicode=true&characterEncoding=utf-8
    driver-class-name: com.mysql.cj.jdbc.Driver
 
#整合mybatis
mybatis.type-aliases-package=com.kuang.pojo
mybatis.mapper-locations=classpath:mybatis/mapper/*.xml

3、测试数据库是否连接成功！

4、创建实体类，导入 Lombok！

Department.java

package com.kuang.pojo;

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;

@Data
@NoArgsConstructor
@AllArgsConstructor
public class Department {

    private Integer id;
    private String departmentName;

}

5、创建mapper目录以及对应的 Mapper 接口

DepartmentMapper.java

//@Mapper : 表示本类是一个 MyBatis 的 Mapper
@Mapper
@Repository
public interface DepartmentMapper {

    // 获取所有部门信息
    List<Department> getDepartments();

    // 通过id获得部门
    Department getDepartment(Integer id);

}

6、对应的Mapper映射文件

DepartmentMapper.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.kuang.mapper.DepartmentMapper">

    <select id="getDepartments" resultType="Department">
       select * from department;
    </select>

    <select id="getDepartment" resultType="Department" parameterType="int">
       select * from department where id = #{id};
    </select>

</mapper>

7、maven配置资源过滤问题

<resources>
    <resource>
        <directory>src/main/java</directory>
        <includes>
            <include>**/*.xml</include>
        </includes>
        <filtering>true</filtering>
    </resource>
</resources>

8、编写部门的 DepartmentController 进行测试！

@RestController
public class DepartmentController {
    
    @Autowired
    DepartmentMapper departmentMapper;
    
    // 查询全部部门
    @GetMapping("/getDepartments")
    public List<Department> getDepartments(){
        return departmentMapper.getDepartments();
    }

    // 查询全部部门
    @GetMapping("/getDepartment/{id}")
    public Department getDepartment(@PathVariable("id") Integer id){
        return departmentMapper.getDepartment(id);
    }
    
}

启动项目访问进行测试！

我们增加一个员工类再测试下，为之后做准备

1、新建一个pojo类 Employee ；

@Data
@AllArgsConstructor
@NoArgsConstructor
public class Employee {

    private Integer id;
    private String lastName;
    private String email;
    //1 male, 0 female
    private Integer gender;
    private Integer department;
    private Date birth;

    private Department eDepartment; // 冗余设计

}

2、新建一个 EmployeeMapper 接口

//@Mapper : 表示本类是一个 MyBatis 的 Mapper
@Mapper
@Repository
public interface EmployeeMapper {

    // 获取所有员工信息
    List<Employee> getEmployees();

    // 新增一个员工
    int save(Employee employee);

    // 通过id获得员工信息
    Employee get(Integer id);

    // 通过id删除员工
    int delete(Integer id);

}

3、编写 EmployeeMapper.xml 配置文件

<?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.kuang.mapper.EmployeeMapper">

    <resultMap id="EmployeeMap" type="Employee">
        <id property="id" column="eid"/>
        <result property="lastName" column="last_name"/>
        <result property="email" column="email"/>
        <result property="gender" column="gender"/>
        <result property="birth" column="birth"/>
        <association property="eDepartment"  javaType="Department">
            <id property="id" column="did"/>
            <result property="departmentName" column="dname"/>
        </association>
    </resultMap>

    <select id="getEmployees" resultMap="EmployeeMap">
        select e.id as eid,last_name,email,gender,birth,d.id as did,d.department_name as dname
        from department d,employee e
        where d.id = e.department
    </select>

    <insert id="save" parameterType="Employee">
        insert into employee (last_name,email,gender,department,birth)
        values (#{lastName},#{email},#{gender},#{department},#{birth});
    </insert>

    <select id="get" resultType="Employee">
        select * from employee where id = #{id}
    </select>

    <delete id="delete" parameterType="int">
        delete from employee where id = #{id}
    </delete>

</mapper>

4、编写EmployeeController类进行测试

@RestController
public class EmployeeController {

    @Autowired
    EmployeeMapper employeeMapper;

    // 获取所有员工信息
    @GetMapping("/getEmployees")
    public List<Employee> getEmployees(){
        return employeeMapper.getEmployees();
    }

    @GetMapping("/save")
    public int save(){
        Employee employee = new Employee();
        employee.setLastName("kuangshen");
        employee.setEmail("qinjiang@qq.com");
        employee.setGender(1);
        employee.setDepartment(101);
        employee.setBirth(new Date());
        return employeeMapper.save(employee);
    }

    // 通过id获得员工信息
    @GetMapping("/get/{id}")
    public Employee get(@PathVariable("id") Integer id){
        return employeeMapper.get(id);
    }

    // 通过id删除员工
    @GetMapping("/delete/{id}")
    public int delete(@PathVariable("id") Integer id){
        return employeeMapper.delete(id);
    }

}

测试结果完成

mybatis 整合流程
1、导入包
2、配置文件
3、mybatis配置
4、编写sql
5、业务层调用dao层
6、controller 调用service层

来源：狂神说（https://t.hk.uy/a35G）