springboot 整合Mybaits-plus

1.为什么要用Mybaits-plus？

你连sql增删改查语句都不用写，人家都写好了，只能说真香。

2.整合Mybaits-plus

（1）勾选Mybaits-plus，以及mysql 驱动

（2）在配置文件中修改数据库配置

spring:
  datasource:
    driver-class-name: com.mysql.cj.jdbc.Driver
    url: jdbc:mysql://localhost:3306/boot_zhaopin?serverTimezone=UTC
    username: root
    password: root

（3）写实体类

public class User {
    private Integer id;
    private String username;
    private String password;
    private String answer1;
    private String answer2;

    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", username='" + username + '\'' +
                ", password='" + password + '\'' +
                ", answer1='" + answer1 + '\'' +
                ", answer2='" + answer2 + '\'' +
                '}';
    }

    public Integer getId() {
        return id;
    }

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

    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 String getAnswer1() {
        return answer1;
    }

    public void setAnswer1(String answer1) {
        this.answer1 = answer1;
    }

    public String getAnswer2() {
        return answer2;
    }

    public void setAnswer2(String answer2) {
        this.answer2 = answer2;
    }
}

（4）定义数据层接口与映射配置，继承BaseMapper（里面增删改查语句都写好了直接用就行）

@Mapper
public interface UserDao extends BaseMapper<User> {
}

（5）测试一下

@SpringBootTest
class MybatisPlusApplicationTests {

    @Autowired
    private UserDao userDao;

    @Test
    void contextLoads() {

        System.out.println(userDao.selectById(1));
        System.out.println(userDao.selectList(null));
    }

}
测试结果：

User{id=1, username='admin', password='e10adc3949ba59abbe56e057f20f883e', answer1='12', answer2='12'}
[User{id=1, username='admin', password='e10adc3949ba59abbe56e057f20f883e', answer1='12', answer2='12'}, User{id=3, username='111', password='b0baee9d279d34fa1dfd71aadb908c3f', answer1='', answer2=''}, User{id=6, username='bai', password='b0baee9d279d34fa1dfd71aadb908c3f', answer1='', answer2=''}]