首页 > 代码库 > Hibernate注解方式实现1-N双向关联
Hibernate注解方式实现1-N双向关联
由于Hibernate可以实现逆向工程,可以自动在数据库中创建表,因此这里不提供数据字典内容。
以微博或博客为例,用户和博客之间属于一对多的关系,即1-N型,在数据库中我们希望构建如下关系
创建用户实体类User:
import ***; /** * @author Barudisshu */ @Entity @Table(name = "t_user", schema = "", catalog = "db_blog") public class User implements Serializable { private int id; //用户自动Id private String username; //用户名 private String password; //密码 private Collection<Post> posts; //用户博客 @Id @Column(name = "id", nullable = false, insertable = true, updatable = true) public int getId() { return id; } public void setId(int id) { this.id = id; } @Basic @Column(name = "username", nullable = true, insertable = true, updatable = true, length = 255) public String getUsername() { return username; } public void setUsername(String username) { this.username = username; } @Basic @Column(name = "password", nullable = true, insertable = true, updatable = true, length = 255) public String getPassword() { return password; } public void setPassword(String password) { this.password = password; } //添加mappedBy属性,否则将创建中间表 @OneToMany(cascade = CascadeType.PERSIST,targetEntity = Post.class,mappedBy = "user") @OrderBy("id") public Collection<Post> getPosts() { return posts; } public void setPosts(Collection<Post> posts) { this.posts = posts; } @Override public boolean equals(Object o) { if (this == o) return true; if (o == null || getClass() != o.getClass()) return false; User user = (User) o; if (id != user.id) return false; if (password != null ? !password.equals(user.password) : user.password != null) return false; if (username != null ? !username.equals(user.username) : user.username != null) return false; return true; } @Override public int hashCode() { int result = id; result = 31 * result + (username != null ? username.hashCode() : 0); result = 31 * result + (password != null ? password.hashCode() : 0); return result; } @Override public String toString() { return ToStringBuilder.reflectionToString(this); } }
下面为博客实体类Post:
import ***; /** * @author Barudisshu */ @Entity @Table(name = "t_post", schema = "", catalog = "db_blog") public class Post implements Serializable{ private int id; //博客自动Id private String title; //博客标题 private Timestamp time; //发布时间 private String digest; //摘要 private String mark; //标记 private String content; //博客正文 private Integer type; //博客分类 private Integer views; //浏览次数 private User user; //博客用户 @Id @Column(name = "id", nullable = false, insertable = true, updatable = true) public int getId() { return id; } public void setId(int id) { this.id = id; } @Basic @Column(name = "title", nullable = true, insertable = true, updatable = true, length = 255) public String getTitle() { return title; } public void setTitle(String title) { this.title = title; } @Basic @Column(name = "time", nullable = true, insertable = true, updatable = true) public Timestamp getTime() { return time; } public void setTime(Timestamp time) { this.time = time; } @Basic @Column(name = "digest", nullable = true, insertable = true, updatable = true, length = 1600) public String getDigest() { return digest; } public void setDigest(String digest) { this.digest = digest; } @Basic @Column(name = "mark", nullable = true, insertable = true, updatable = true, length = 255) public String getMark() { return mark; } public void setMark(String mark) { this.mark = mark; } @Basic @Column(name = "content", nullable = true, insertable = true, updatable = true, length = 2147483647) public String getContent() { return content; } public void setContent(String content) { this.content = content; } @Basic @Column(name = "type", nullable = true, insertable = true, updatable = true) public Integer getType() { return type; } public void setType(Integer type) { this.type = type; } @Basic @Column(name = "views", nullable = true, insertable = true, updatable = true) public Integer getViews() { return views; } public void setViews(Integer views) { this.views = views; } @ManyToOne(cascade = CascadeType.PERSIST,targetEntity = User.class) public User getUser() { return user; } public void setUser(User user) { this.user = user; } @Override public boolean equals(Object o) { if (this == o) return true; if (o == null || getClass() != o.getClass()) return false; Post post = (Post) o; if (id != post.id) return false; if (content != null ? !content.equals(post.content) : post.content != null) return false; if (digest != null ? !digest.equals(post.digest) : post.digest != null) return false; if (mark != null ? !mark.equals(post.mark) : post.mark != null) return false; if (time != null ? !time.equals(post.time) : post.time != null) return false; if (title != null ? !title.equals(post.title) : post.title != null) return false; if (type != null ? !type.equals(post.type) : post.type != null) return false; if (views != null ? !views.equals(post.views) : post.views != null) return false; return true; } @Override public int hashCode() { int result = id; result = 31 * result + (title != null ? title.hashCode() : 0); result = 31 * result + (time != null ? time.hashCode() : 0); result = 31 * result + (digest != null ? digest.hashCode() : 0); result = 31 * result + (mark != null ? mark.hashCode() : 0); result = 31 * result + (content != null ? content.hashCode() : 0); result = 31 * result + (type != null ? type.hashCode() : 0); result = 31 * result + (views != null ? views.hashCode() : 0); return result; } @Override public String toString() { return ToStringBuilder.reflectionToString(this); } }
Hibernate注解方式实现1-N双向关联
声明:以上内容来自用户投稿及互联网公开渠道收集整理发布,本网站不拥有所有权,未作人工编辑处理,也不承担相关法律责任,若内容有误或涉及侵权可进行投诉: 投诉/举报 工作人员会在5个工作日内联系你,一经查实,本站将立刻删除涉嫌侵权内容。