请对上面回答的代码进行一次Advert对象的保存操作

可以使用 JPA 的 EntityManager 来进行 Advert 对象的保存操作。例如：

@Autowired
private EntityManager entityManager;

@Transactional
public void saveAdvert(Advert advert) {
    entityManager.persist(advert);
}

这里使用了 @Transactional 注解来开启事务，确保保存操作的原子性。然后使用 EntityManager 的 persist 方法来保存 Advert 对象。

相关问题

请将上面回答中对应AdvertMapper.xml对应的AdvertMapper.java文件内容展示出来

好的，假设您的AdvertMapper.xml文件中包含了类似以下的内容：

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
  "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
  
<mapper namespace="com.example.mapper.AdvertMapper">
  
  <select id="getAdvertById" parameterType="int" resultType="com.example.model.Advert">
    SELECT * FROM adverts WHERE id = #{id}
  </select>
  
  <insert id="insertAdvert" parameterType="com.example.model.Advert">
    INSERT INTO adverts (title, description, created_at) VALUES (#{title}, #{description}, #{createdAt})
  </insert>
  
  <update id="updateAdvert" parameterType="com.example.model.Advert">
    UPDATE adverts SET title = #{title}, description = #{description}, updated_at = #{updatedAt} WHERE id = #{id}
  </update>
  
  <delete id="deleteAdvert" parameterType="int">
    DELETE FROM adverts WHERE id = #{id}
  </delete>
  
</mapper>

那么对应的AdvertMapper.java文件应该是类似以下的内容：

package com.example.mapper;

import com.example.model.Advert;
import org.apache.ibatis.annotations.*;

public interface AdvertMapper {

  @Select("SELECT * FROM adverts WHERE id = #{id}")
  public Advert getAdvertById(int id);

  @Insert("INSERT INTO adverts (title, description, created_at) VALUES (#{title}, #{description}, #{createdAt})")
  public int insertAdvert(Advert advert);

  @Update("UPDATE adverts SET title = #{title}, description = #{description}, updated_at = #{updatedAt} WHERE id = #{id}")
  public int updateAdvert(Advert advert);

  @Delete("DELETE FROM adverts WHERE id = #{id}")
  public int deleteAdvert(int id);

}

请注意，上面这个Java接口中的方法名和参数类型、注解等需要与AdvertMapper.xml文件中的SQL语句对应。这样MyBatis才能正确地自动将Java对象和数据库表之间进行映射。

请将上一个回答中的四张表的orm对象在springboot的项目中使用java注解演示出来

好的，以下是在 Spring Boot 项目中使用 Java 注解定义四张表的 ORM 对象示例：

1. 广告表 `advert` 的 ORM 对象：

@Entity
@Table(name = "advert")
public class Advert {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "id")
    private Long id;

    @Column(name = "name")
    private String name;

    @Column(name = "start_date")
    private Date startDate;

    @Column(name = "end_date")
    private Date endDate;

    @Column(name = "link")
    private String link;

    @Column(name = "status")
    private Integer status;

    @ManyToOne
    @JoinColumn(name = "position_id")
    private AdPosition position;

    @ManyToOne
    @JoinColumn(name = "media_id")
    private MediaFile mediaFile;

    // 省略 getter 和 setter 方法
}

2. 广告位置表 `ad_position` 的 ORM 对象：

@Entity
@Table(name = "ad_position")
public class AdPosition {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "id")
    private Long id;

    @Column(name = "name")
    private String name;

    @Column(name = "width")
    private Integer width;

    @Column(name = "height")
    private Integer height;

    // 省略 getter 和 setter 方法
}

3. 广告媒体表 `media_file` 的 ORM 对象：

@Entity
@Table(name = "media_file")
public class MediaFile {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "id")
    private Long id;

    @Column(name = "name")
    private String name;

    @Column(name = "type")
    private Integer type;

    @Column(name = "url")
    private String url;

    @Column(name = "create_time")
    private Date createTime;

    @Column(name = "update_time")
    private Date updateTime;

    // 省略 getter 和 setter 方法
}

4. 广告点击表 `advert_click` 的 ORM 对象：

@Entity
@Table(name = "advert_click")
public class AdvertClick {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "id")
    private Long id;

    @ManyToOne
    @JoinColumn(name = "advert_id")
    private Advert advert;

    @Column(name = "click_time")
    private Date clickTime;

    @Column(name = "click_ip")
    private String clickIp;

    // 省略 getter 和 setter 方法
}

这里使用了 `@Entity` 注解来标记实体类，`@Table` 注解来指定对应的数据库表名称，`@Id` 注解来标记主键字段，`@GeneratedValue` 注解用于指定主键生成策略，`@Column` 注解用于指定字段对应的数据库列名，`@ManyToOne` 注解用于指定多对一关联关系，`@JoinColumn` 注解用于指定外键列名。