springboot对mybatis的整合

1. 导入依赖

首先新建一个springboot项目，勾选组件时勾选Spring Web、JDBC API、MySQL Driver
pom.xml配置文件导入依赖

<!--mybatis-spring-boot-starter-->
        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
            <version>2.1.4</version>
        </dependency>

2. 连接数据库
使用idea链接数据库
idea右上方选择database,新建一个数据源,我的是mysql,就创建的mysql的数据源

成功则会

查看user表

3. 编写数据库配置信息
在springboot配置文件application.properties中配置数据库信息

spring.datasource.username=root
spring.datasource.password=123456
spring.datasource.url=jdbc:mysql://localhost:3306/mybatis?useUnicode=true&characterEncoding=utf-8
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver

4. 编写pojo实体类
在主程序同级目录下新建pojo包，其中新建User实体类(使用了lombok减少了代码量)
使用lombok需要pom.xml导入依赖

<dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.18.20</version>
        </dependency>

User实体类:

package cn.dzp.pojo;

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;

@Data
@AllArgsConstructor
@NoArgsConstructor
public class User {
    private int id;
    private String name;
    private String pwd;
}

5. 编写mapper接口
在主程序同级目录下新建mapper包，其中新建UserMapper接口

package cn.dzp.mapper;

import cn.dzp.pojo.User;
import org.apache.ibatis.annotations.Mapper;
import org.apache.ibatis.annotations.Param;
import org.springframework.stereotype.Repository;

import java.util.List;

@Mapper//这个注解表示了这是一个mybatis的mapper类:Dao
@Repository
public interface UserMapper {
    List<User> queryUserList();

    User queryUserById(@Param("id") int id);

    int addUser(User user);

    int deleteUserById(int id);

    int updateUser(User user);
}

6. 编写mapper.xml
在resources目录下新建mabatis包，其中新建mapper包，再在其中新建mapper.xml

代码如下:

<?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="cn.dzp.mapper.UserMapper">
    <select id="queryUserList" resultType="user">
        select * from user
    </select>

    <select id="queryUserById" resultType="user">
        select * from user where id=#{id}
    </select>

    <insert id="addUser" parameterType="user">
        insert into user values (#{id},#{name},#{pwd})
    </insert>

    <update id="updateUser" parameterType="user">
        update user set name=#{name},pwd=#{pwd} where id = #{id}
    </update>

    <delete id="deleteUserById">
        delete * from user where id = #{id}
    </delete>
</mapper>

然后需要到springboot核心配置文件application.properties中绑定mapper.xml文件

#整合mybatis
mybatis.type-aliases-package=cn.dzp.pojo
mybatis.mapper-locations=classpath:mybatis/mapper/*.xml

7. 编写controller
在主程序同级目录下新建controller包，在其中新建UserController

package cn.dzp.controller;

import cn.dzp.mapper.UserMapper;
import cn.dzp.pojo.User;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import java.util.List;

@RestController
public class UserController {
    @Autowired
    private UserMapper userMapper;

    @RequestMapping("/queryUserList")
    public List<User> queryUserList(){
        List<User> users = userMapper.queryUserList();
        for (User user : users) {
            System.out.println(user);
        }
        return users;
    }

    @GetMapping("/queryUserByID")
    public User queryUserByID() {
        User user = userMapper.queryUserById(2);
        return user;
    }

    @GetMapping("/addUser")
    public String addUser() {
        userMapper.addUser(new User(5, "Godas_Lsy", "89720"));
        return "增加用户OK";
    }

    @GetMapping("/updateUser")
    public String updateUser() {
        userMapper.updateUser(new User(5, "Godas_Lsy", "123456"));
        return "修改用户OK";
    }

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