配置准备

引入依赖

在pom.xml文件中引入数据库和mybatis相关依赖

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

<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
</dependency>

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

配置文件

spring:
  datasource:
    driver-class-name: com.mysql.cj.jdbc.Driver
    url: jdbc:mysql://localhost:3306/forum22?serverTimezone=Asia/Shanghai
    username: 数据库登录账号
    password: 数据库登录密码

#下面这些内容是为了让MyBatis映射
mybatis:
  mapper-locations: classpath:com/example/forum/dao/*xml #指定Mybatis的Mapper文件
  type-aliases-package: com.example.forum.pojo #指定Mybatis的实体目录

使用

创建实体类

引入依赖(可选)

引入lombook依赖，此依赖可以简化实体类的创建与维护

<dependency>
    <groupId>org.projectlombok</groupId>
    <artifactId>lombok</artifactId>
    <optional>true</optional>
</dependency>

实体类

package com.example.forum.pojo;

import lombok.Data;

import java.util.Date;

/**
 * @author gs_huang
 */

@Data
public class User {

    private Integer id;
    private String username;
    private String password;
    private Date createTime;
    private String avatar;
    private String nickname;
    private String signature;
    private String introduction;
    private Integer rankExperience;
    private Integer rank;
    private Integer articleCount;
    private Integer commentCount;
    private Integer roleId;
    private String status;

}

创建映射接口

package com.example.forum.dao;

import com.example.forum22.pojo.User;
import org.apache.ibatis.annotations.Mapper;
import org.apache.ibatis.annotations.ResultMap;
import org.apache.ibatis.annotations.Select;

import java.util.List;

/**
 * @author gs_huang
 */
@Mapper
public interface UserDao {

    /**
     * 查询所有用户信息
     * @return 所有用户信息
     */
    @Select("select * from user")
    @ResultMap("UserMap")
    List<User> findAll();

}

创建映射文件

<?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.forum.dao.UserDao">

    <resultMap id="UserMap" type="User">
        <result column="id" property="id"/>
        <result column="username" property="username" />
        <result column="password" property="password" />
        <result column="create_time" property="createTime"/>
        <result column="avatar" property="avatar" />
        <result column="nickname" property="nickname" />
        <result column="signature" property="signature" />
        <result column="introduction" property="introduction" />
        <result column="rank_experience" property="rankExperience" />
        <result column="rank" property="rank" />
        <result column="article_count" property="articleCount" />
        <result column="comment_count" property="commentCount" />
        <result column="role_id" property="roleId" />
        <result column="status" property="status" />

    </resultMap>
</mapper>

测试

package com.example.forum.dao;

import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;

import static org.junit.jupiter.api.Assertions.*;

@SpringBootTest
class UserDaoTest {

    @Autowired
    private UserDao userDao;

    @Test
    void findAll() {
        System.out.println(userDao.findAll());
    }
}

总结

1. 引入依赖
2. 创建实体类
3. 创建接口
4. 测试