Mybatis 的入门简单运用介绍

Mybatis 用于操作数据库

操作数据库肯定需要:

1.SQL语句

2.数据库对象和 java 对象的映射

接下来我们看看怎么使用 Mybatis

我们先搞一些数据库内容

-- 创建数据库
DROP DATABASE IF EXISTS mybatis_test;
CREATE DATABASE mybatis_test DEFAULT CHARACTER SET utf8mb4;
-- 使⽤数据数据
USE mybatis_test;
-- 创建表[⽤⼾表]
DROP TABLE IF EXISTS userinfo;
CREATE TABLE `userinfo` (
 `id` INT ( 11 ) NOT NULL AUTO_INCREMENT,
 `username` VARCHAR ( 127 ) NOT NULL,
 `password` VARCHAR ( 127 ) NOT NULL,
 `age` TINYINT ( 4 ) NOT NULL,
 `gender` TINYINT ( 4 ) DEFAULT '0' COMMENT '1-男 2-⼥ 0-默认',
 `phone` VARCHAR ( 15 ) DEFAULT NULL,
 `delete_flag` TINYINT ( 4 ) DEFAULT 0 COMMENT '0-正常, 1-删除',
 `create_time` DATETIME DEFAULT now(),
 `update_time` DATETIME DEFAULT now(),
 PRIMARY KEY ( `id` ) 
) ENGINE = INNODB DEFAULT CHARSET = utf8mb4; 
-- 添加⽤⼾信息
INSERT INTO mybatis_test.userinfo ( username, `password`, age, gender, phone )
VALUES ( 'admin', 'admin', 18, 1, '18612340001' );
INSERT INTO mybatis_test.userinfo ( username, `password`, age, gender, phone )
VALUES ( 'zhangsan', 'zhangsan', 18, 1, '18612340002' );
INSERT INTO mybatis_test.userinfo ( username, `password`, age, gender, phone )
VALUES ( 'lisi', 'lisi', 18, 1, '18612340003' );
INSERT INTO mybatis_test.userinfo ( username, `password`, age, gender, phone )
VALUES ( 'wangwu', 'wangwu', 18, 1, '18612340004' );

然后创建 Spring  Initializr 项目

然后下一步配置这四个东西,那个Mysql Driver 也在SQL里面,往下滑就能找到,然后再下一步就能写代码了

创建一个类,然后里面写Java对象,要和数据库对象进行映射

package com.example.mybatisdemo.model;


import lombok.Data;

import java.util.Date;
@Data
public class UserInfo {
    private Integer id;
    private String username;
    private String password;
    private Integer age;
    private Integer gender;
    private String photo;
    private Integer deleteFlag;
    private Date createTime;
    private Date updateTime;
}

再创建一个接口实现 select * from

package com.example.mybatisdemo.mapper;

import com.example.mybatisdemo.model.UserInfo;
import org.apache.ibatis.annotations.Mapper;
import org.apache.ibatis.annotations.Select;

import java.util.List;

@Mapper
public interface UserInfoMapper {
    @Select("select * from userInfo")
    List selectAll();
}

再写一个类证明上述代码是否可以实现

package com.example.mybatisdemo.Controller;

import com.example.mybatisdemo.mapper.UserInfoMapper;
import com.example.mybatisdemo.model.UserInfo;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RestController;

import java.util.List;

@RestController
public class UserInfoController {
    @Autowired
    private UserInfoMapper userInfoMapper;

    public List selectAll(){
        return userInfoMapper.selectAll();
    }
}

别忘了在application.yml 中配置url

# 数据库连接配置
spring:
  datasource:
    url: jdbc:mysql://127.0.0.1:3306/mybatis_test?characterEncoding=utf8&useSSL=false
    username: root
    password: 123456
    driver-class-name: com.mysql.cj.jdbc.Driver

然后我们在浏览器中进行访问,成功拿到

Mybatis 的运用就是这么简单