Mybatis入门之在基于Springboot的框架下拿到MySQL中数据

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
     xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0</modelVersion>
 
  <!--所有项目的父工程 指定了springboot工程的版本-->
  <parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>3.2.5</version>
    <relativePath/> <!-- lookup parent from repository -->
  </parent>
 
  <!-- Generated by https://start.springboot.io -->
  <!-- 优质的 spring/boot/data/security/cloud 框架中文文档尽在 => https://springdoc.cn -->
  <groupId>com.bigdate</groupId>
  <artifactId>Mybatis</artifactId>
  <version>0.0.1-SNAPSHOT</version>
  <name>Mybatis</name>
  <description>Mybatis</description>
  <properties>
    <java.version>17</java.version>
  </properties>
  <dependencies>
 
    <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-web</artifactId>
    </dependency>
 
    <!--mybatis起步依赖-->
    <dependency>
      <groupId>org.mybatis.spring.boot</groupId>
      <artifactId>mybatis-spring-boot-starter</artifactId>
      <version>3.0.3</version>
    </dependency>
 
    <!--MySQL驱动包-->
    <dependency>
      <groupId>com.mysql</groupId>
      <artifactId>mysql-connector-j</artifactId>
      <scope>runtime</scope>
    </dependency>
 
    <!--Springboot单元测试所需要的依赖-->
    <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-test</artifactId>
      <scope>test</scope>
    </dependency>
 
    <dependency>
      <groupId>org.mybatis.spring.boot</groupId>
      <artifactId>mybatis-spring-boot-starter-test</artifactId>
      <version>3.0.3</version>
      <scope>test</scope>
    </dependency>
 
  </dependencies>
 
  <build>
    <plugins>
      <plugin>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-maven-plugin</artifactId>
      </plugin>
    </plugins>
  </build>
 
</project>

package com.bigdate.mybatis.pojo;
 
public class User {
    private Integer id;
    private String name;
    private Short age;
    private Short gender;
    private String phone;
 
    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;
    }
 
    /**
     * 获取
     * @return id
     */
    public Integer getId() {
        return id;
    }
 
    /**
     * 设置
     * @param id
     */
    public void setId(Integer id) {
        this.id = id;
    }
 
    /**
     * 获取
     * @return name
     */
    public String getName() {
        return name;
    }
 
    /**
     * 设置
     * @param name
     */
    public void setName(String name) {
        this.name = name;
    }
 
    /**
     * 获取
     * @return age
     */
    public Short getAge() {
        return age;
    }
 
    /**
     * 设置
     * @param age
     */
    public void setAge(Short age) {
        this.age = age;
    }
 
    /**
     * 获取
     * @return gender
     */
    public Short getGender() {
        return gender;
    }
 
    /**
     * 设置
     * @param gender
     */
    public void setGender(Short gender) {
        this.gender = gender;
    }
 
    /**
     * 获取
     * @return phone
     */
    public String getPhone() {
        return phone;
    }
 
    /**
     * 设置
     * @param phone
     */
    public void setPhone(String phone) {
        this.phone = phone;
    }
 
    public String toString() {
        return "User{id = " + id + ", name = " + name + ", age = " + age + ", gender = " + gender + ", phone = " + phone + "}";
    }
}

spring.application.name=Mybatis
 
#配置数据库的链接信息
 
#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

package com.bigdate.mybatis.mapper;
 
 
import com.bigdate.mybatis.pojo.User;
import org.apache.ibatis.annotations.Mapper;
import org.apache.ibatis.annotations.Select;
 
import java.util.List;
 
@Mapper//表示当前是Mybatis的一个接口 此时程序运行时框架会自动生成实现类对象(代理对象) 并交给spring的ioc容器
public interface UserMapper {
 
    //查询全部用户信息
    @Select("select * from user")
    public List<User> list();
 
}

package com.bigdate.mybatis;
 
import com.bigdate.mybatis.mapper.UserMapper;
import com.bigdate.mybatis.pojo.User;
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 //springboot整合单元测试的注解
 
class MybatisApplicationTests {
 
    @Autowired //依赖注入方式
    private UserMapper userMapper;
 
    @Test
    public void testListUser(){
       List <User> userList =userMapper.list();
       userList.stream().forEach(user -> {
          System.out.println(user);
       });
    }
 
}