SpringBoot整合Mybatis

 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 解决时区报错
    url: jdbc:mysql://localhost:3306/test?serverTimezone=UTC&useUnicode=true&CharacterEncoding=utf-8
    driver-class-name: com.mysql.jdbc.Driver
    # 数据库连接池
    type: com.alibaba.druid.pool.DruidDataSource
    druid:
      #  最大连接池数量
      max-active: 20
      # 初始化连接池的数量
      initial-size: 5
      # 最小连接池 数量
      min-idle: 2
      # 这里建议配置为TRUE，防止取到的连接不可用
      test-on-borrow: true
      test-on-return: false
      # 验证连接有效与否的SQL，不同的数据配置不同
      validation-query: select
      #通过别名的方式配置扩展插件，常用的插件有：
      #监控统计用的filter:stat日志用的filter:log4j防御sql注入的filter:wall
      filters: stat,slf4j,wall
      #  配置获取连接等待超时的时间 单位毫秒
      max-wait: 6000
# mybatis 配置
mybatis:
  mapper-locations: classpath:mapper/*.xml
  # 别名
  type-aliases-package: com.csp.pojo
  # settings 下的配置
  configuration:
    # 开启驼峰命名功能 其它的一些属性参考 mybatis-config.xml中的settings属性
    map-underscore-to-camel-case: true

3、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;

}

4、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);

　　// 新增部门
   int save(Department department);

}

5、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>

    <insert id="save" parameterType="Department">
        insert into Department (departmentName) values (#{departmentName});
    </insert>

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

</mapper>

6、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>

7、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);
    }  
}

 

注：也可以直接在 Mapper 类上面添加注解@Mapper，如下所示：

package com.wangzaiplus.test.mapper;

import com.wangzaiplus.test.pojo.User;
import org.apache.ibatis.annotations.*;
import org.apache.ibatis.type.JdbcType;

import java.util.List;

public interface UserMapper {

    @Select("select * from user")
    @Results({
            @Result(property = "username", column = "username", jdbcType = JdbcType.VARCHAR),
            @Result(property = "password", column = "password")
    })
    List<User> selectAll();

    @Select("select * from user where id = #{id}")
    @Results({
            @Result(property = "username", column = "username", jdbcType = JdbcType.VARCHAR),
            @Result(property = "password", column = "password")
    })
    User selectOne(Integer id);

    @Insert("insert into user(username, password) values(#{username}, #{password})")
    void insert(User user);

    @Update("update user set username=#{username}, password=#{password} where id = #{id}")
    void update(User user);

    @Delete("delete from user where id = #{id}")
    void delete(Integer id);

}