mybatis( MyBatis Spring-boot-sta

创建项目：

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创建测试表

在数据库中：创建测试表

create table user
(
    id bigint not null AUTO_INCREMENT comment '主键' primary key,
    age int null comment '年龄',
    password varchar(32) null comment '密码',
    sex int null comment '性别',
    username varchar(32) null comment '用户名'
);

配置数据源

修改配置文件：配置数据源：application.yml

spring:
  #profiles: dev
  datasource:
    url: jdbc:mysql://localhost:3306/helloworld?useUnicode=true&characterEncoding=utf8&serverTimezone=UTC
    username: root
    password: root
    driver-class-name: com.mysql.cj.jdbc.Driver

编写代码

创建实体类 User.java

public class User {
    private Long id;
    private String username;
    private String password;
    private Integer age;
    private Integer sex;

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    public Integer getAge() {
        return age;
    }

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

    public Integer getSex() {
        return sex;
    }

    public void setSex(Integer sex) {
        this.sex = sex;
    }

    public Long getId() {
        return id;
    }

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

创建访问接口 UserMapper ( 注意需要用 @Mapper注解)

import com.example.demo4mybatis.entity.User;
import org.apache.ibatis.annotations.Mapper;
import org.apache.ibatis.annotations.Param;
import org.apache.ibatis.annotations.Select;

import java.util.List;

@Mapper
public interface UserMapper {
    @Select("select * from user")
    List<User> selectAll();

    @Select("select * from user where USERNAME= #{user_name} ")
    User selectByName(@Param("user_name") String userName);
}

测试代码

    @Autowired
    private UserMapper userMapper;

    @Test
    public void test() {
        List<User> list = userMapper.selectAll();
        System.out.println("--" + list.size());

        User user = userMapper.selectByName("张三丰");
        System.out.println("--" + user);
    }