小编anh*_*yen的帖子

我正在尝试使用多对多关系更新 2 个表：

我有2个班级：

供应商.java：

@Entity
@Table(name = "Suppliers")
public class Supplier implements Serializable {

@Id
String id;
String name;

@ManyToMany(fetch = FetchType.LAZY, cascade = CascadeType.ALL)
@JoinTable(name = "Suppliers_Categories", joinColumns = { @JoinColumn(name = "SupplierId") }, inverseJoinColumns = { @JoinColumn(name = "CategoryId") })
Set<Category> categories = new HashSet<Category>();

@OneToMany(mappedBy = "supplier")
Collection<Product> products;

public Set<Category> getCategories() {
    return this.categories;
}

public void setCategories(Set<Category> categories) {
    this.categories = categories;
}

public String getId() {
    return id;
}

public void setId(String id) …