java - 如何编写Java hibernate 多对多关系检索查询

我有下面指定的两个表。我想编写一个查询以获取特定组的所有联系人。（根据组ID）。请帮我。
提前致谢。

1.该联系人表，它与联系人组表有很多关系。

@Entity
@Table(name="contacts")
public class Contacts implements Serializable {
private Long id;
private String userId;
private String emailId;
private Set<ContactGroups> contactGroups;
private String firstName;
private String lastName;

@Id
@Column(name="id")
@GeneratedValue(strategy=GenerationType.AUTO)
public Long getId() {
    return id;
}
public void setId(Long id) {
    this.id = id;
}

@Column(name="user_id")
public String getUserId() {
    return userId;
}
public void setUserId(String userId) {
    this.userId = userId;
}

@Column(name="email_id")
public String getEmailId() {
    return emailId;
}
public void setEmailId(String emailId) {
    this.emailId = emailId;
}

@ManyToMany(targetEntity = ContactGroups.class, cascade =          {CascadeType.ALL},fetch=FetchType.EAGER)
@JoinTable(name="contact_group",
    joinColumns=@JoinColumn(name="c_id", referencedColumnName="id"),
    inverseJoinColumns=@JoinColumn(name="g_id", referencedColumnName="id")
)
public Set<ContactGroups> getContactGroups() {
    return contactGroups;
}
public void setContactGroups(Set<ContactGroups> contactGroups) {
    this.contactGroups = contactGroups;
}

@Column(name="first_name")
public String getFirstName() {
    return firstName;
}
public void setFirstName(String firstName) {
    this.firstName = firstName;
}
@Column(name="last_name")
public String getLastName() {
    return lastName;
}
public void setLastName(String lastName) {
    this.lastName = lastName;
}


 }





 @Entity
 @Table(name="contact_groups")
 public class ContactGroups implements Serializable{
private Long id;
private String groupName;
private String userName;

@Id
@GeneratedValue(strategy=GenerationType.AUTO)
public Long getId() {
    return id;
}
public void setId(Long id) {
    this.id = id;
}

@Column(name="user_name")
public String getUserName() {
    return userName;
}
public void setUserName(String userName) {
    this.userName = userName;
}

@Column(name="group_name")
public String getGroupName() {
    return groupName;
}
public void setGroupName(String groupName) {
    this.groupName = groupName;
}


}

最佳答案

select c from Contacts c
inner join c.contactGroups group
where group.id = :groupId

但是如果


您将实体命名为ContactGroup和Contact（没有最后一个s）
您将关联映射为双向关联。这将允许通过ID获取ContactGroup，只需调用getContacts()即可获取其联系人。

关于java - 如何编写Java hibernate 多对多关系检索查询，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/11290096/