使用连接表休眠一对多，并休眠注释 [英] hibernate one to many using a join table, and hibernate annotations

问题描述

我想使用连接表在两个表之间建立一对多关系.

I want do a one-to-many relationship between two tables using a join table.

这就是我想使用连接表的原因:

This is why I want to use a join table:

• 休眠单向一对多关联 - 为什么连接表更好?
• 为什么是否建议避免外键上的单向一对多关联?

最后，我想使用 Hibernate 注释来执行此操作.

Finally, I want to use Hibernate annotations to perform this.

我找到了一些使用 xml 映射来做到这一点的示例，但没有使用注释.

I found some examples to do this using xml mapping but nothing with annotations.

我相信这就是需要创建表的方式

I believe this would be how the tables need to be created

CREATE TABLE `PRODUCT` (
  `PRODUCT_ID`      BIGINT       PRIMARY KEY AUTO_INCREMENT
);

CREATE TABLE `PARTS` (
  `PART_ID`         BIGINT       PRIMARY KEY AUTO_INCREMENT
);

-- USER_IMAGE_ID must be unique if we want a one-to-many relationship between PRODUCTS & PARTS tables
CREATE TABLE `USER_DETAILS_IMAGE` (
  `PRODUCT_ID`      BIGINT,
  `PART_ID`         BIGINT UNIQUE,
  CONSTRAINT `FK_PRODUCT_ID`  FOREIGN KEY (`PRODUCT_ID`)   REFERENCES `PRODUCT`(`PRODUCT_ID`),
  CONSTRAINT `FK_PART_ID`     FOREIGN KEY (`PART_ID`)      REFERENCES `PARTS`(`PART_ID`)
);

推荐答案

不要寻找示例.阅读 官方文档:

Don't look for examples. Read the official documentation:

@Entity
public class Product {

    private String serialNumber;
    private Set<Part> parts = new HashSet<Part>();

    @Id
    public String getSerialNumber() { return serialNumber; }
    void setSerialNumber(String sn) { serialNumber = sn; }

    @OneToMany
    @JoinTable(
            name="PRODUCT_PARTS",
            joinColumns = @JoinColumn( name="PRODUCT_ID"),
            inverseJoinColumns = @JoinColumn( name="PART_ID")
    )
    public Set<Part> getParts() { return parts; }
    void setParts(Set parts) { this.parts = parts; }
}


@Entity
public class Part {
   ...
}

另外，请注意这是单向一对多关联的默认设置.因此，如果默认表和列名称适合您，您甚至不必提供 @JoinTable 注释.

Also, note that this is the default for unidirectional one-to-many associations. So you don't even have to provide the @JoinTable annotation if the default table and column names suit you.

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