MyBatis笔记01-入门

1、准备工作

创建springboot工程、数据库表user、实体类User

创建springboot工程如下：

引入MyBatis相关依赖,勾选MyBatis相关选项

准备数据库表user

create table user(
    id int unsigned primary key auto_increment comment 'ID',
    name varchar(100) comment '姓名',
    age tinyint unsigned comment '年龄',
    gender tinyint unsigned comment '性别, 1:男, 2:女',
    phone varchar(11) comment '手机号'
) comment '用户表';

insert into user(id, name, age, gender, phone) VALUES (null,'白眉鹰王',55,'1','18800000000');
insert into user(id, name, age, gender, phone) VALUES (null,'金毛狮王',45,'1','18800000001');
insert into user(id, name, age, gender, phone) VALUES (null,'青翼蝠王',38,'1','18800000002');
insert into user(id, name, age, gender, phone) VALUES (null,'紫衫龙王',42,'2','18800000003');
insert into user(id, name, age, gender, phone) VALUES (null,'光明左使',37,'1','18800000004');
insert into user(id, name, age, gender, phone) VALUES (null,'光明右使',48,'1','18800000005');

创建实体类User:

package com.itheima.pojo;

public class User {
    private Integer id;
    private String name;
    private short age;
    private Short gender;
    private String address;

    //有参构造
    public User(Integer id, String name, short age, Short gender, String address) {
        this.id = id;
        this.name = name;
        this.age = age;
        this.gender = gender;
        this.address = address;
    }

    //无参构造
    public User() {
    }

    //get和set方法
    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public short getAge() {
        return age;
    }

    public void setAge(short age) {
        this.age = age;
    }

    public Short getGender() {
        return gender;
    }

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

    public String getAddress() {
        return address;
    }

    public void setAddress(String address) {
        this.address = address;
    }

    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", name='" + name + ''' +
                ", age=" + age +
                ", gender=" + gender +
                ", address='" + address + ''' +
                '}';
    }
}

2、配置MyBatis

在application.properties文件里面

spring.application.name=springboot-mybatis-quickstart
#配置数据库的连接信息 --四要素
#驱动类名称
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver
#数据库连接的url
spring.datasource.url=jdbc:mysql://localhost:3306/mybatis
#连接数据库的用户名
spring.datasource.username=root
#连接数据库的密码
spring.datasource.password=123456

3、编写SQL语句（注解/XML）

定义一个持久层的接口UserMapper 创建一个mapper的文件夹，把该文件放到下面去

package com.itheima.springboot.mapper;
import com.itheima.springboot.pojo.User;
import org.apache.ibatis.annotations.Mapper;
import org.apache.ibatis.annotations.Select;

import java.util.List;

@Mapper//运行时，该接口会自动生成实现类对象（代理对象），并且将该对象交给IOC容器管理
public interface UserMapper {
    //查询全部的用户信息
    @Select("select * from user")
    public List<User> list();
}

测试：在test目录下 在该测试文件下可以调用UserMapper来执行相关的SQL语句：查询全部的用户信息

@SpringBootTest//springboot整合单元测试的注解
class SpringbootMybatisDemo1ApplicationTests {

    @Autowired//完成依赖注入
    private UserMapper userMapper;

    @Test
    public void testListUser(){
        List<User> userList = userMapper.list();//直接调用userMapper来查询所有的用户数据
        userList.stream().forEach(user -> {
            System.out.println(user);
        });
    }

}

运行该测试，结果如下