01-Mybatis入门介绍

MyBatis官网：mybatis – MyBatis 3 | 简介

 

1）创建spingboot工程

2）配置mybatis的相关依赖，以及数据库连接信息

3）配置数据库表user，以及实体类User

package com.itheima.entity;

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

    public User() {
    }

    public User(Integer id, String name, Short age, Short gender, String phone) {
        this.id = id;
        this.name = name;
        this.age = age;
        this.gender = gender;
        this.phone = phone;
    }

    private String phone;



    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 getPhone() {
        return phone;
    }

    public void setPhone(String phone) {
        this.phone = phone;
    }


    @java.lang.Override
    public java.lang.String toString() {
        return "User{" +
                "id=" + id +
                ", name='" + name + '\'' +
                ", age=" + age +
                ", gender=" + gender +
                ", phone='" + phone + '\'' +
                '}';
    }

}

4）配置mapper接口，UserMapper.java

package com.itheima.mapper;

import com.itheima.entity.User;
import org.apache.ibatis.annotations.Mapper;
import org.apache.ibatis.annotations.Select;

import java.util.List;

// @Mapper注解，声明这是一个Mapper接口，在运行时会动态生成该接口的实现类对象（代理对象），并且将该对象交给Spring容器管理
@Mapper
public interface UserMapper {

    // 查询全部用户信息
    @Select("select * from user")
    public List<User> list();

}

5）spring单元测试，SpringbootMybatisQuickstartApplicationTests.java

package com.itheima;

import com.itheima.entity.User;
import com.itheima.mapper.UserMapper;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;

import java.util.List;

// @SpringBootTest注解，用于SpringBoot整合单元测试的注解
@SpringBootTest
class SpringbootMybatisQuickstartApplicationTests {

    // @Autowired注解，自动注入UserMapper接口的代理对象
    @Autowired
    private UserMapper userMapper;

    @Test
    public void testListUser(){
        // 调用代理对象的方法，执行SQL语句
        List<User> userList = userMapper.list();
        // 遍历输出查询结果
        userList.stream().forEach(user -> {
            System.out.println(user);
        });
    }
}