单向N-N关联必须使用连接表。
Company实体：
package com.ydoing.hibernate5;
import java.util.HashSet;
import java.util.Set;
import javax.persistence.CascadeType;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.JoinTable;
import javax.persistence.ManyToMany;
import javax.persistence.Table;
@Entity
@Table(name = "company_inf")
public class Company {
@Id
@Column(name = "company_id")
@GeneratedValue(strategy = GenerationType.IDENTITY)
private Integer id;
private String name;
@ManyToMany(targetEntity = Product.class, cascade = CascadeType.ALL)
@JoinTable(name = "company_product", joinColumns = @JoinColumn(name = "company_id", referencedColumnName = "company_id"), inverseJoinColumns = @JoinColumn(name = "product_id", referencedColumnName = "product_id"))
private Set<Product> products = new HashSet<>();
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Set<Product> getProducts() {
return products;
}
public void setProducts(Set<Product> products) {
this.products = products;
}
}Product实体：
package com.ydoing.hibernate5;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.Table;
@Entity
@Table(name = "product_inf")
public class Product {
@Id
@Column(name = "product_id")
@GeneratedValue(strategy = GenerationType.IDENTITY)
private Integer id;
private String name;
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
}Console输出：
Hibernate:
insert
into
company_inf
(name)
values
(?)
Hibernate:
select
last_insert_id()
Hibernate:
insert
into
product_inf
(name)
values
(?)
Hibernate:
select
last_insert_id()
Hibernate:
insert
into
product_inf
(name)
values
(?)
Hibernate:
select
last_insert_id()
Hibernate:
insert
into
company_product
(company_id, product_id)
values
(?
, ?
) Hibernate: insert into company_product (company_id, product_id) values (?
, ?
)
从输出不难看出。Hibernate创建了连接表company_product。
数据库表： 
