我試圖讓 Hibernate 創建一個多對多關系連接表。物體表創建得很好，但連接表不會顯示。一些源手動創建連接表，其他源（如 Youtube 教程）解釋了它們是如何由 Hibernate 自動創建的。
這是我的第一個物體表：
package com.presents;
import javax.persistence.*;
import java.io.Serial;
import java.io.Serializable;
import java.util.Set;
@Entity
@Table(name = "articles")
public class Article implements Serializable {
@Serial
private static final long serialVersionUID = 1L;
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
@Column(name = "id")
private int id;
@Column(name = "name")
private String name;
@Column(name = "link")
private String url;
@Column(name = "likes")
private int likes;
@Column(name = "clicks")
private int clicks;
@ManyToMany(cascade = { CascadeType.ALL })
@JoinTable(
name = "category_article",
joinColumns = {
@JoinColumn(name = "article_id", referencedColumnName = "id")
},
inverseJoinColumns = {
@JoinColumn(name = "category_id", referencedColumnName = "id")
}
)
public Set<Categories> categories = new HashSet<>();;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getUrl() {
return url;
}
public void setUrl(String url) {
this.url = url;
}
public int getLikes() {
return likes;
}
public void setLikes(int likes) {
this.likes = likes;
}
public int getClicks() {
return clicks;
}
public void setClicks(int clicks) {
this.clicks = clicks;
}
public Set<Categories> getCategories() {
return cats;
}
public void setCategories(Set<Categories> categories) {
this.cats = categories;
}
}
這是我的第二個物體表：
包com.presents;
import javax.persistence.*;
import java.io.Serial;
import java.io.Serializable;
import java.util.HashSet;
import java.util.Set;
@Entity
@Table(name = "category")
public class Categories implements Serializable {
@Serial
private static final long serialVersionUID = 1L;
@Id
@GeneratedValue(strategy=GenerationType.AUTO)
@Column(name = "id")
private int id;
@Column(name = "category")
private String category;
@ManyToMany(mappedBy = "categories")
public Set<Article> articles = new HashSet<>();
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public void setCategory(String category) {
this.category = category;
}
public String getCategory() {
return category;
}
public void setArticles(Set<Article> articles) {
this.articles = articles;
}
public Set<Article> getArticles() {
return articles;
}
}
這個想法是任何文章都可以屬于多個類別，但不止一個類別可以應用于任何文章。
I am using a SQLite3 database, but I tried also with a MySQL database, both to no avail. Hibernate seems somehow to avoid the many-to-many annotation completely. It does not complain about it when I ran the code and seems to avoid it altogether. Again, the other to tables are created beautifully, without me fumbling around with any SQL commands. Why is Hibernate refusing to create the join table, and how do I fix it?
Here is the output of Hibernate:
INFO: HHH000412: Hibernate ORM core version 5.6.2.Final
Dez. 18, 2021 8:41:14 AM org.hibernate.annotations.common.reflection.java.JavaReflectionManager <clinit>
INFO: HCANN000001: Hibernate Commons Annotations {5.1.2.Final}
Dez. 18, 2021 8:41:15 AM org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl configure
WARN: HHH10001002: Using Hibernate built-in connection pool (not for production use!)
Dez. 18, 2021 8:41:15 AM org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl buildCreator
INFO: HHH10001005: using driver [org.sqlite.JDBC] at URL [jdbc:sqlite:presents.db]
Dez. 18, 2021 8:41:15 AM org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl buildCreator
INFO: HHH10001001: Connection properties: {}
Dez. 18, 2021 8:41:15 AM org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl buildCreator
INFO: HHH10001003: Autocommit mode: false
Dez. 18, 2021 8:41:15 AM org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl$PooledConnections <init>
INFO: HHH000115: Hibernate connection pool size: 20 (min=1)
Dez. 18, 2021 8:41:15 AM org.hibernate.dialect.Dialect <init>
INFO: HHH000400: Using dialect: org.hibernate.dialect.SQLiteDialect
Hibernate: drop table if exists articles
Hibernate: drop table if exists category
Hibernate: drop table if exists hibernate_sequence
Hibernate: create table articles (id integer not null, name varchar, link varchar, likes integer, clicks integer, primary key (id))
Hibernate: create table category (id integer not null, category varchar, primary key (id))
Hibernate: create table hibernate_sequence (next_val bigint)
Hibernate: insert into hibernate_sequence values ( 1 )
Dez. 18, 2021 8:41:16 AM org.hibernate.resource.transaction.backend.jdbc.internal.DdlTransactionIsolatorNonJtaImpl getIsolatedConnection
INFO: HHH10001501: Connection obtained from JdbcConnectionAccess [org.hibernate.engine.jdbc.env.internal.JdbcEnvironmentInitiator$ConnectionProviderJdbcConnectionAccess@334ebcaa] for (non-JTA) DDL execution was not in auto-commit mode; the Connection 'local transaction' will be committed and the Connection will be set into auto-commit mode.
Dez. 18, 2021 8:41:16 AM org.hibernate.resource.transaction.backend.jdbc.internal.DdlTransactionIsolatorNonJtaImpl getIsolatedConnection
INFO: HHH10001501: Connection obtained from JdbcConnectionAccess [org.hibernate.engine.jdbc.env.internal.JdbcEnvironmentInitiator$ConnectionProviderJdbcConnectionAccess@107bfcb2] for (non-JTA) DDL execution was not in auto-commit mode; the Connection 'local transaction' will be committed and the Connection will be set into auto-commit mode.
Dez. 18, 2021 8:41:16 AM org.hibernate.engine.transaction.jta.platform.internal.JtaPlatformInitiator initiateService
INFO: HHH000490: Using JtaPlatform implementation: [org.hibernate.engine.transaction.jta.platform.internal.NoJtaPlatform]
Hibernate: select next_val as id_val from hibernate_sequence
Hibernate: update hibernate_sequence set next_val= ? where next_val=?
Hibernate: select next_val as id_val from hibernate_sequence
Hibernate: update hibernate_sequence set next_val= ? where next_val=?
Hibernate: select next_val as id_val from hibernate_sequence
Hibernate: update hibernate_sequence set next_val= ? where next_val=?
Hibernate: select next_val as id_val from hibernate_sequence
Hibernate: update hibernate_sequence set next_val= ? where next_val=?
Hibernate: select next_val as id_val from hibernate_sequence
Hibernate: update hibernate_sequence set next_val= ? where next_val=?
Hibernate: select next_val as id_val from hibernate_sequence
Hibernate: update hibernate_sequence set next_val= ? where next_val=?
Hibernate: select next_val as id_val from hibernate_sequence
Hibernate: update hibernate_sequence set next_val= ? where next_val=?
Hibernate: insert into articles (name, link, likes, clicks, id) values (?, ?, ?, ?, ?)
Hibernate: insert into articles (name, link, likes, clicks, id) values (?, ?, ?, ?, ?)
Hibernate: insert into articles (name, link, likes, clicks, id) values (?, ?, ?, ?, ?)
Hibernate: insert into articles (name, link, likes, clicks, id) values (?, ?, ?, ?, ?)
Hibernate: insert into category (category, id) values (?, ?)
Hibernate: insert into category (category, id) values (?, ?)
Hibernate: insert into category (category, id) values (?, ?)
Hibernate: select categories0_.id as id1_1_, categories0_.category as category2_1_ from category categories0_
uj5u.com熱心網友回復：
您需要獲取一篇文章，然后添加一個類別并保存它。例如：
Categories category = categoryRepository.getById(100001);
article.getCategories().add(category);
articlesRepository.save(article);
productRepository.findAll();
這將向 category_article 表中添加一個新條目。
uj5u.com熱心網友回復：
我自己發現了錯誤。當我應該使用 Hibernate XML 映射時，我使用了 JPA 注釋。在洗掉每個注釋并在 XML 映射檔案中創建必要的行之后，該表出現了。
轉載請註明出處，本文鏈接：https://www.uj5u.com/qiye/388096.html