MyBatis简单使用笔记

1.引入依赖

        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
            <version>2.2.2</version>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </dependency>

2.application.properties配置

spring.datasource.url=jdbc:mysql://127.0.0.1/book891?useUnicode=true&characterEncoding=utf-8&serverTimezone=UTC&useSSL=true
spring.datasource.username=root
spring.datasource.password=rootroot
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver
spring.jpa.properties.hibernate.hbm2ddl.auto=update
spring.jpa.properties.hibernate.dialect=org.hibernate.dialect.MySQL5InnoDBDialect
spring.jpa.show-sql= true
spring.datasource.initialize=true
spring.datasource.initialization-mode=always
spring.datasource.schema=classpath:db/schema.sql
spring.thymeleaf.cache=false
server.port=8080

3.resources路径下的db文件创建,schema.sql

DROP TABLE IF EXISTS `user`;
CREATE TABLE `user` (
    `id` int(11) NOT NULL AUTO_INCREMENT,
     `name` varchar(255) DEFAULT NULL,
     `age` int(11) DEFAULT NULL,
     PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

4.User实体对象模型创建

import lombok.Data;

/**
 * Copyfright(C),2022-2022,复兴元宇科技有限公司
 * FileName:User Author:yz Date:2022/3/28 11:15
 */
@Data
public class User {
    private int id;
    private String name;
    private int age;
}

5.实体和数据表的映射关系

import java.util.List;

/**
 * Copyfright(C),2022-2022,复兴元宇科技有限公司
 * FileName:UserMapper Author:yz Date:2022/3/28 11:17
 */
@Mapper
public interface UserMapper {

    @Select("SELECT * FROM user WHERE id = #{id}")
    User queryById(@Param("id") int id);

    @Select("SELECT * FROM user limit 1000")
    List<User> queryAll();

    @Insert({"INSERT INTO user(name,age) VALUES(#{name},#{age})"})
    int add(User user);

    @Delete("DELETE FROM user WHERE id = #{id}")
    int delById(int id);

    @Update("UPDATE user SET name=#{name},age=#{age} WHERE id = #{id}")
    int updateById(User user);

}

6.实现实体和数据表的映射关系

package com.example.demo.mapper;

import com.example.demo.model.User;
import org.apache.ibatis.annotations.*;

import java.util.List;

/**
 * Copyfright(C),2022-2022,复兴元宇科技有限公司
 * FileName:UserMapper Author:yz Date:2022/3/28 11:17
 */
@Mapper
public interface UserMapper {

    @Select("SELECT * FROM user WHERE id = #{id}")
    User queryById(@Param("id") int id);

    @Select("SELECT * FROM user limit 1000")
    List<User> queryAll();

    @Insert({"INSERT INTO user(name,age) VALUES(#{name},#{age})"})
    int add(User user);

    @Delete("DELETE FROM user WHERE id = #{id}")
    int delById(int id);

    @Update("UPDATE user SET name=#{name},age=#{age} WHERE id = #{id}")
    int updateById(User user);

}

7.实现增删改查功能

package com.example.demo.controller;

import com.example.demo.mapper.UserMapper;
import com.example.demo.model.User;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import java.util.List;

/**
 * Copyfright(C),2022-2022,复兴元宇科技有限公司
 * FileName:UserController Author:yz Date:2022/3/28 11:32
 */
@RestController
@RequestMapping("/user")
public class UserController {

    @Autowired
    UserMapper userMapper;

    @RequestMapping("/querybyid")
    User queryById(int id) {
        return userMapper.queryById(id);
    }

    @RequestMapping("/")
    List<User> queryAll() {
        return userMapper.queryAll();
    }


    @RequestMapping("/add")
    String add(User user) {
        return userMapper.add(user) == 1 ? "success" : "failed";
    }

    @RequestMapping("/updatebyid")
    String updateById(User user) {
        return userMapper.updateById(user) == 1 ? "success" : "failed";
    }

    @RequestMapping("/delbyid")
    String delById(int id) {
        return userMapper.delById(id) == 1 ? "success" : "failed";
    }
}