Springboot3学习（2、接入MyBatis）

Springboot3学习——接入MyBatis（二）

前言

上文我们使用官方模版，成功运行了Springboot项目。详见Springoot3学习——搭建SpringBoot（一）

目录结构

如下图所示

整合MyBatis

1、在项目对象模型pom.xml中插入mybatis的配置

		<dependency>
			<groupId>org.mybatis.spring.boot</groupId>
			<artifactId>mybatis-spring-boot-starter</artifactId>
			<version>3.0.3</version>
		</dependency>
		<dependency>
			<groupId>mysql</groupId>
			<artifactId>mysql-connector-java</artifactId>
			<version>8.0.33</version>
		</dependency>

2、添加数据库连接相关配置，application.properties

spring.datasource.url=jdbc:mysql://localhost:3306/sugar
spring.datasource.username=root
spring.datasource.password=lyh2016
spring.datasource.driver-class-name=com.mysql.jdbc.Driver

3、创建数据库sugar以及user表

SET NAMES utf8mb4;
SET FOREIGN_KEY_CHECKS = 0;

-- ----------------------------
-- Table structure for user
-- ----------------------------
DROP TABLE IF EXISTS `user`;
CREATE TABLE `user`  (
  `userid` varchar(50) CHARACTER SET utf8 COLLATE utf8_general_ci NOT NULL COMMENT '用户编号',
  `username` varchar(50) CHARACTER SET utf8 COLLATE utf8_general_ci NOT NULL COMMENT '用户名称',
  `dept` varchar(50) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL COMMENT '所属部门',
  `status` varchar(30) CHARACTER SET utf8 COLLATE utf8_general_ci NOT NULL COMMENT '用户状态 ',
  `password` varchar(50) CHARACTER SET utf8 COLLATE utf8_general_ci NOT NULL COMMENT '密码',
  `gender` varchar(30) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL COMMENT '性别',
  `createuid` varchar(50) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL COMMENT '创建用户',
  `transdatetime` datetime NULL DEFAULT NULL COMMENT '创建时间',
  PRIMARY KEY (`userid`) USING BTREE,
  INDEX `userid`(`userid`) USING BTREE
) ENGINE = InnoDB CHARACTER SET = gbk COLLATE = gbk_chinese_ci ROW_FORMAT = DYNAMIC;

-- ----------------------------
-- Records of user
-- ----------------------------
INSERT INTO `user` VALUES ('SV001', 'admin', 'IT', '1', '123', '男', 'admin', '2024-10-16 13:34:00');

创建三层以及对应demo代码

创建包，分别是controller/service/impl/dao/pojo, 创建后目录如下

• controller：存放控制器类，这些类处理HTTP请求，并与服务层进行交互。
• service：存放服务接口，定义业务逻辑，由服务实现类实现。
• impl：存放服务接口的实现类，是服务层的具体实现。
• dao：数据访问层，存放与数据库交互的接口，通常与数据库中的表对应。
• pojo：Plain Old Java Object的缩写，存放简单的Java对象，这些对象通常用于封装数据

具体代码如下

添加User

package com.ziyan.pojo;

public class User {
    private String userid;
    private String username;
    private String dept;
    private String status;
    private String password;
    private String gender;
    private String createruid;
    private String transdatetime;

    public String getUserid() {
        return userid;
    }

    public void setUserid(String userid) {
        this.userid = userid;
    }

    public String getUsername() {
        return username;
    }

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

    public String getDept() {
        return dept;
    }

    public void setDept(String dept) {
        this.dept = dept;
    }

    public String getStatus() {
        return status;
    }

    public void setStatus(String status) {
        this.status = status;
    }

    public String getPassword() {
        return password;
    }

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

    public String getGender() {
        return gender;
    }

    public void setGender(String gender) {
        this.gender = gender;
    }

    public String getCreateruid() {
        return createruid;
    }

    public void setCreateruid(String createruid) {
        this.createruid = createruid;
    }

    public String getTransdatetime() {
        return transdatetime;
    }

    public void setTransdatetime(String transdatetime) {
        this.transdatetime = transdatetime;
    }
}

添加userMapper (os：为什么叫userMapper，而不叫UserDao啊，原来主要是因为MyBatis的官方习惯和约定俗成的命名规则，其实一样)

package com.ziyan.dao;

import com.ziyan.pojo.User;
import org.apache.ibatis.annotations.Mapper;
import org.apache.ibatis.annotations.Select;

@Mapper
public interface UserMapper {
    @Select("SELECT userid,username,dept,gender FROM USER WHERE userid=#{userid}")
    User getUser(String userid);
}

添加UserService

package com.ziyan.service;

import com.ziyan.pojo.User;

public interface UserService {
    User getUser(String userid);
}

添加UserServiceImpl

package com.ziyan.service.impl;

import com.ziyan.dao.UserMapper;
import com.ziyan.pojo.User;
import com.ziyan.service.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

@Service
public class UserServiceImpl implements UserService {
    @Autowired
    UserMapper userMapper;

    @Override
    public User getUser(String userid) {
        return userMapper.getUser(userid);
    }
}

添加LoginController

package com.ziyan.controller;

import com.ziyan.pojo.User;
import com.ziyan.service.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class LoginController {
    @Autowired
    UserService userService;
    @GetMapping("/show")
    public User getUser(String userid){
        return userService.getUser(userid);
    }
}

(ps：这边需要引入注解@RestController，需要的依赖spring-boot-starter-web)

<dependency>
	<groupId>org.springframework.boot</groupId>
	<artifactId>spring-boot-starter-web</artifactId>
</dependency>

修改ZypApplication,添加@ComponentScan，@MapperScan注解，并指定目录

@ComponentScan(basePackages = {"com.ziyan.controller","com.ziyan.service"})
@MapperScan(basePackages = {"com.ziyan.dao"})

运行成功

如下图：

若出现提示：Loading class com.mysql.jdbc.Driver'. This is deprecated. The new driver class is com.mysql.cj.jdbc.Driver’. The driver is automatically registered via the SPI and manual loading of the driver class is generally unnecessary.报错

ps：这个报错信息表明你正在尝试加载一个已经不再被推荐使用的MySQL JDBC驱动类com.mysql.jdbc.Driver。从MySQL Connector/J 5.1版本开始，推荐使用com.mysql.cj.jdbc.Driver这个新的驱动类。我们的MySql是8.0的，修改配置文件。

 spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver