SpringBoot整合Mybatis

使用SpringBoot 2.1.4版本

1. 建表

使用的是MySQL，运行以下SQL语句，建立t_user表，并插入4条记录

-- 创建数据库
create database IF NOT EXISTS `springboot_mybatis` default character set utf8mb4 collate utf8mb4_general_ci;

use springboot_mybatis;

SET NAMES utf8mb4;
SET FOREIGN_KEY_CHECKS = 0;

-- ----------------------------
-- Table structure for t_user
-- ----------------------------
DROP TABLE IF EXISTS `t_user`;
CREATE TABLE `t_user`  (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `user_name` varchar(20) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NULL DEFAULT NULL,
  `password` varchar(255) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NULL DEFAULT NULL,
  PRIMARY KEY (`id`) USING BTREE
) ENGINE = InnoDB AUTO_INCREMENT = 5 CHARACTER SET = utf8mb4 COLLATE = utf8mb4_general_ci ROW_FORMAT = Dynamic;

-- ----------------------------
-- Records of t_user
-- ----------------------------
INSERT INTO `t_user` VALUES (1, 'LiMing', '123');
INSERT INTO `t_user` VALUES (2, 'ZhangHong', '456');
INSERT INTO `t_user` VALUES (3, '小刚', '789');
INSERT INTO `t_user` VALUES (4, 'Srammy', '@12#34$');

SET FOREIGN_KEY_CHECKS = 1;

2.引入依赖

<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <scope>runtime</scope>
</dependency>
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
    <groupId>org.mybatis.spring.boot</groupId>
    <artifactId>mybatis-spring-boot-starter</artifactId>
    <version>2.0.1</version>
</dependency>

3. 编写实体类

public class User {
    private int userId;
    private String username;
    private String password;

    public int getUserId() {
        return userId;
    }

    public void setUserId(int userId) {
        this.userId = userId;
    }

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }
}

4. 编写Dao层

这里提供了两个方法，一是查询所有，二是根据id查询

@Repository
public interface UserDao {
    List<User> getAllUsers();
    User findUserById(@Param("userId") Integer userId);
}

5. 编写Service层

@Service
public class UserService {

    @Autowired
    private UserDao userDao;

    public List<User> getAllUsers() {
        return userDao.getAllUsers();
    }

    public User findUserById(int userId) {
        User user = userDao.findUserById(userId);
        return user;
    }
}

6. 编写Controller层

@RestController
public class UserController {

    @Autowired
    private UserService userService;

    @GetMapping(value = "/all")
    public List<User> getAllUsers() {
        return userService.getAllUsers();
    }

    @GetMapping(value = "/finduser/{id}")
    public User findUserById(@PathVariable(name = "id" ) Integer id) {
        return userService.findUserById(id);
    }
}

7. 编写Mapper.xml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="deom.srammy.springbootmybatis.dao.UserDao">
    <resultMap id="BaseResultMap"  type="deom.srammy.springbootmybatis.model.User">
        <id column="id" jdbcType="INTEGER" property="userId" />
        <result column="user_name" jdbcType="VARCHAR" property="username" />
        <result column="password" jdbcType="VARCHAR" property="password" />
    </resultMap>

    <select id="getAllUsers" resultMap="BaseResultMap">
          select id,user_name,password
           from t_user
          order by id desc
    </select>


    <select id="findUserById" parameterType="int" resultMap="BaseResultMap">
         select id,user_name,password from t_user
         where id = #{userId}
    </select>

</mapper>

8. 启动类中配置扫描包的路径

在SpringBoot中配置扫描包地址，然后生成dao层的bean，之后被注入到Service层中

@SpringBootApplication
@MapperScan("deom.srammy.springbootmybatis.dao") // 配置扫描包的路径，将dao层和mapper.xml文件关联
public class SpringbootmybatisApplication {

    public static void main(String[] args) {
        SpringApplication.run(SpringbootmybatisApplication.class, args);
    }
}

9. 配置文件application.properties

# 访问端口
server.port = 8089  
# MYSQL配置
spring.datasource.url=jdbc:mysql://localhost:3306/springboot_mybatis?useUnicode=true&characterEncoding=utf-8&serverTimezone=GMT%2B8&useSSL=false
spring.datasource.username=root
spring.datasource.password=123456
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver
# Mybatis配置
mybatis.mapper-locations=classpath:mapper/*.xml # 指定mapper.xml文件的路径

10. 工程结构

11.启动，访问

在浏览器中输入url进行访问，返回的是json串