SpringBoot整合MyBatis

Posted 2021-07-05 dxj1016

Mybatis开发手册

Maven仓库地址

整合步骤：

1. 新建springboot项目springboot-mybatis-study，选择模块
   
   
2. 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>

3. 配置数据库连接信息

spring:
  datasource:
    username: root
    password: root
    #?serverTimezone=UTC解决时区的报错
    url: jdbc:mysql://localhost:3306/test1?serverTimezone=UTC&useUnicode=true&characterEncoding=utf-8
    driver-class-name: com.mysql.jdbc.Driver

4. 测试数据库是否连接成功！

package com.spring;
import org.junit.jupiter.api.AfterAll;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import javax.sql.DataSource;
import java.sql.SQLException;
@SpringBootTest
class SpringbootMybatisStudyApplicationTests {
    @Autowired
    DataSource dataSource;
    @Test
    void contextLoads() throws SQLException {
        System.out.println(dataSource.getClass());
        System.out.println(dataSource.getConnection());
    }
}

5. 启动项目如果报如下错误，那么看看你一开始创建项目的时候是用的阿里云还是spring官网，我这里用到阿里云，所以创建项目的时候就给properties配置文件配置好了数据库，所以再自己写个yml配置数据库的时候，如果没有指定使用哪个，那么默认是使用properties中的，因为properties中的是阿里云自动创建的，用户名和密码没有对应上我们本地的，所以连接失败了
   
   
   
6. 没有报错
   
7. 导入lombok，如果之前没有下lombok要先在idea中下载lombok插件然后再导入lombok依赖

<dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
        </dependency>

8. 创建数据库表user

-- ----------------------------
DROP TABLE IF EXISTS `user`;
CREATE TABLE `user`  (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `name` varchar(255) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL,
  `password` varchar(8) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL,
  PRIMARY KEY (`id`) USING BTREE
) ENGINE = InnoDB AUTO_INCREMENT = 10 CHARACTER SET = utf8 COLLATE = utf8_general_ci COMMENT = 'password' ROW_FORMAT = Dynamic;

-- ----------------------------
-- Records of a
-- ----------------------------
INSERT INTO `user` VALUES (4, '1016', '1016');
INSERT INTO `user` VALUES (5, '1', NULL);
INSERT INTO `user` VALUES (6, '2', NULL);
INSERT INTO `user` VALUES (7, 'dxj1016', 'dxj1016');
INSERT INTO `user` VALUES (8, 'dxj1016', 'dxj1016');
INSERT INTO `user` VALUES (9, 'dxj1016', 'dxj1016');

9. 创建实体类User.java

package com.spring.pojo;
import lombok.Data;
@Data
@AllArgsConstructor
public class User {
    private Integer id;
    private String name;
    private String password;
      public User(String name, String password) {
        this.name = name;
        this.password = password;
    }
}

5. 创建mapper目录以及对应的 Mapper 接口UserMapper.java

package com.spring.mapper;
import com.spring.pojo.User;
import org.apache.ibatis.annotations.Mapper;
import org.springframework.stereotype.Repository;
import java.util.List;
//@Mapper : 表示本类是一个 MyBatis 的 Mapper
@Mapper
@Repository
public interface UserMapper {
    // 获取所有部门信息
    List<User> queryUserList();
    // 通过id获得部门
    User queryUserById(Integer id);
    //    添加用户
    int addUser(User user);
    //    修改用户
    int updateUser(User user);
    //    删除用户
    int deleteUser(int id);
}

6. 在resources文件夹下建mybatis文件夹，再在mybatis文件夹下建mapper文件夹，在里面建对应的Mapper映射文件UserMapper.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.spring.mapper.UserMapper">
    <select id="queryUserList" resultType="User">
       select * from user;
    </select>
    <select id="queryUserById" resultType="User" parameterType="int">
       select * from user where id = #{id};
    </select>
    <insert id="addUser" parameterType="User">
        insert into user (name,password) values (#{name},#{password});
    </insert>
    <update id="updateUser" parameterType="User">
        update user set name=#{name},password=#{password} where id=#{id};
    </update>
    <delete id="deleteUser" parameterType="int">
        delete from user where id=#{id};
    </delete>
</mapper>

7. 配置文件yml中整合mybatis

# 整合mybatis
mybatis:
  type-aliases-package: com.spring.pojo
  # 这个路径是映射文件的路径，对应自己路径下的映射文件，否则测试找不到这个映射文件。
  mapper-locations: classpath:mybatis/mapper/*.xml

8. 编写controller层测试

package com.spring.controller;

import com.spring.mapper.UserMapper;
import com.spring.pojo.User;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RestController;
import java.util.List;

@RestController
public class UserController {

    @Autowired
    UserMapper userMapper;

    // 查询全部部门
    @GetMapping("/queryUserList")
    public List<User> queryUserList() {
        return userMapper.queryUserList();
    }

    // 根据id查询用户
    @GetMapping("/queryUserById/{id}")
    public User queryUserById(@PathVariable("id") Integer id) {
        return userMapper.queryUserById(id);
    }

    //    添加用户
    @GetMapping("/addUser")
    public String addUser() {
        userMapper.addUser(new User("阿毛", "34334"));
        return "add OK";
    }

    //    修改用户
    @GetMapping("/updateUser")
    public String updateUser() {
        userMapper.updateUser(new User(6, "小红", "490333"));
        return "udpate OK";
    }

    //    删除用户
    @GetMapping("/deleteUser")
    public String deleteUser() {
        userMapper.deleteUser(5);
        return "delete OK";
    }
}

总结整合mybatis过程：

1. 导入依赖
2. 配置文件
3. mybatis配置
4. 编写sql
5. 业务层（service）调用dao层
6. controller层调用service层
   注意：上面步骤中省略了service层