Spring Boot Mybatis使用

Posted 2023-02-18 @carefree

Mybatis

MyBatis的前身是Apache社区的一个开源项目iBatis，于2010年更名为MyBatis。MyBatis是支持定制化SQL、存储过程以及高级映射的优秀的持久层框架，避免了几乎所有的JDBC代码和手动设置参数以及获取结果集，使得开发人员更加关注SQL本身和业务逻辑，不用再去花费时间关注整个复杂的JDBC操作过程。

pom.xml 整合

        <!--MyBatis配置-->
        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
            <version>2.2.2</version>
        </dependency>

配置项
mybatis.config-location
mybatis.mapper-locations
mybatis.type-aliases-package

# mybatis config
mybatis.mapper-locations=classpath:mapper/*Dao.xml

注解
@Mapper
@MapperScan

@MapperScan("com.example.mybatis_demo.dao")

application.properties

server.port=9999
spring.datasource.driverClassName=com.mysql.cj.jdbc.Driver
spring.datasource.url=jdbc:mysql://localhost:3306/yanjing?useUnicode=true&serverTimezone=Asia/Shanghai&characterEncoding=utf8&autoReconnect=true&useSSL=false&allowMultiQueries=true
spring.datasource.username=root
spring.datasource.password=root
# mybatis config
mybatis.mapper-locations=classpath:mapper/*Dao.xml

entity（bean）-> User.java

package com.example.mybatis_demo.entity;

import lombok.Data;

@Data
public class User 
    private Integer id;
    private String name;
    private String password;

dao（mapper）->UserDao.java

package com.example.mybatis_demo.dao;

import com.example.mybatis_demo.entity.User;

import java.util.List;

public interface UserDao 
    /**
     * 查，返回数据列表
     * @return
     */
    List<User> findAllusers();
    /**
     * 增
     * @return
     */
    int insertUser(User user);
    /**
     * 改
     * @return
     */
    int updateUser(User user);
    /**
     * 删
     * @return
     */
    int delUser(Integer id);

编写sql语句
resources->mapper->UserDao.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.example.mybatis_demo.dao.UserDao">
    <resultMap id="UserResult" type="com.example.mybatis_demo.entity.User">
        <result property="id" column="id"/>
        <result property="name" column="name"/>
        <result property="password" column="password"/>
    </resultMap>

    <select id="findAllusers" resultMap="UserResult">
        select * from user
    </select>

    <insert id="insertUser" parameterType="com.example.mybatis_demo.entity.User">
        insert into user(name,password)
        values (#name,#password)
    </insert>

    <update id="updateUser" parameterType="com.example.mybatis_demo.entity.User">
        update user
        set
        name=#name,password=#password
        where id = #id
    </update>

    <delete id="delUser" parameterType="int">
        delete from user where id = #id
    </delete>

</mapper>

控制器
controller->MybatisController.java

package com.example.mybatis_demo.controller;

import com.example.mybatis_demo.dao.UserDao;
import com.example.mybatis_demo.entity.User;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;
import org.thymeleaf.util.StringUtils;

import javax.annotation.Resource;
import java.util.List;

@RestController
public class MybatisController 

    @Resource
    UserDao userDao;

    @GetMapping("/users/mybatis/queryall")      //http://localhost:9999/users/mybatis/queryall
    public List<User> queryAll ()
        return userDao.findAllusers();
    

    //新增一条数据    http://localhost:9999/users/mybatis/insert?name=assd&password=assd
    @GetMapping("/users/mybatis/insert")
    public Boolean insert(String name,String password)
        if (StringUtils.isEmpty(name) || StringUtils.isEmpty(password))
            return false;
        
        User user = new User();
        user.setName(name);
        user.setPassword(password);
        return userDao.insertUser(user) > 0 ;
    

    //修改一条数据 http://localhost:9999/users/mybatis/update?id=2&name=update&password=update
    @GetMapping("/users/mybatis/update")
    public Boolean update(Integer id,String name,String password)
        if (id == null || id < 1 || StringUtils.isEmpty(name) || StringUtils.isEmpty(password))
            return false;
        
        User user = new User();
        user.setId(id);
        user.setName(name);
        user.setPassword(password);
        return userDao.updateUser(user) > 0 ;
    

    //删除一条数据        localhost:9999/users/mybatis/delete?id=3
    @GetMapping("/users/mybatis/delete")
    public Boolean delete(Integer id)
        if(id == null || id < 1 )
            return false;
        
        return userDao.delUser(id) > 0;
    

启动类

package com.example.mybatis_demo;

import org.mybatis.spring.annotation.MapperScan;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@MapperScan("com.example.mybatis_demo.dao")		//扫描dao层接口
@SpringBootApplication
public class MybatisDemoApplication 

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

controller层拦截用户请求，entity（bean）层定义对象，dao（mapper）层声明方法，UserDao.xml实现SQL语句，完成操作数据库的目的。
使用mybatis实现数据库的增删改查！
参考：https://edu.csdn.net/learn/26258/328801