Java 具有附加属性且不将多对多映射为单独实体的多对多

下面的例子很好用，hovewer我想让你检查一下这是否是一个好方法，因为我以前没有这样的要求，我很好奇应该怎么做

我有三个表：EMPLOYEE、MEETING、EMPLOYEE_MEETING，对于员工和会议之间的多对多关系，只有两个映射。似乎我能够插入、加载和更新所有内容。我想要实现的不是为关系创建额外的映射、DAO和单独的模型

CREATE TABLE "employee_meeting" (
  "employee_id" bigint(20) NOT NULL,
  "meeting_id" bigint(20) NOT NULL,
  "opinion" varchar(50) DEFAULT NULL,
  PRIMARY KEY ("employee_id","meeting_id"),
 KEY "FK_MEETING" ("meeting_id"),
CONSTRAINT "FK_EMPLOYEE" FOREIGN KEY ("employee_id") REFERENCES "employee"      ("employee_id"),
 CONSTRAINT "FK_MEETING" FOREIGN KEY ("meeting_id") REFERENCES "meeting" ("meeting_id")
) ENGINE=InnoDB DEFAULT CHARSET=latin1$$


<hibernate-mapping package="net.viralpatel.hibernate">

<class name="Employee" table="EMPLOYEE">
    <id name="employeeId" column="EMPLOYEE_ID">
        <generator class="native" />
    </id>

    <property name="firstname" />
    <property name="lastname" column="lastname" />


<set name="meetings" table="EMPLOYEE_MEETING" inverse="false" lazy="false" fetch="select" cascade="all" >
    <key column="EMPLOYEE_ID" />
    <composite-element class="EmployeeMeeting">
        <parent name="employee" />
        <many-to-one name="meeting" column="MEETING_ID" not-null="true" cascade="all"
            class="Meeting" />
        <property name="opinion" column="OPINION" />
    </composite-element>
</set> 


</class>

---

以这种方式将Manty减少到多个集合，而无需双向，就等于一个集合

我建议尊重多对多集合，在

Meeting

下创建

Employee

的数组并定义双向映射

---

hibernate的版本是什么？

从会议课上，我不需要接触员工。。我只需要从员工级别访问会议-让员工我需要插入、更新、删除会议

我做了一些测试，它似乎起作用了。奇怪的是，当我运行此代码时，我只是从数据库加载数据：

Employee e2 = (Employee) session.load(Employee.class, new Long(18));
    Employee e = (Employee) session.load(Employee.class, new Long(17));
    Iterator i = e.getMeetings().iterator();
    while (i.hasNext()){
        System.out.println(((EmployeeMeeting) i.next()).getMeeting().getMeetingId());
    }
    System.out.println(e2.getMeetings().iterator().next().getMeeting().getMeetingId());

    session.getTransaction().commit();
    session.close();

当我只从数据库加载数据时，为什么HIbernate会删除和插入会议

 Hibernate: select employee0_.EMPLOYEE_ID as EMPLOYEE1_0_0_, employee0_.firstname as     firstname0_0_, employee0_.lastname as lastname0_0_ from EMPLOYEE employee0_ where     employee0_.EMPLOYEE_ID=?
 Hibernate: select meetings0_.EMPLOYEE_ID as EMPLOYEE1_0_, meetings0_.MEETING_ID as      MEETING2_0_, meetings0_.OPINION as OPINION0_ from EMPLOYEE_MEETING meetings0_           where meetings0_.EMPLOYEE_ID=?
 Hibernate: select employee0_.EMPLOYEE_ID as EMPLOYEE1_0_0_, employee0_.firstname as firstname0_0_, employee0_.lastname as lastname0_0_ from EMPLOYEE employee0_ where employee0_.EMPLOYEE_ID=?
 Hibernate: select meetings0_.EMPLOYEE_ID as EMPLOYEE1_0_, meetings0_.MEETING_ID as MEETING2_0_, meetings0_.OPINION as OPINION0_ from EMPLOYEE_MEETING meetings0_ where meetings0_.EMPLOYEE_ID=?
12
11
7
13
7
Hibernate: delete from EMPLOYEE_MEETING where EMPLOYEE_ID=? and MEETING_ID=?
Hibernate: insert into EMPLOYEE_MEETING (EMPLOYEE_ID, MEETING_ID, OPINION) values (?, ?, ?)
Hibernate: delete from EMPLOYEE_MEETING where EMPLOYEE_ID=? and MEETING_ID=?
Hibernate: delete from EMPLOYEE_MEETING where EMPLOYEE_ID=? and MEETING_ID=?
Hibernate: delete from EMPLOYEE_MEETING where EMPLOYEE_ID=? and MEETING_ID=?
Hibernate: delete from EMPLOYEE_MEETING where EMPLOYEE_ID=? and MEETING_ID=?
Hibernate: insert into EMPLOYEE_MEETING (EMPLOYEE_ID, MEETING_ID, OPINION) values (?,   ?, ?)
Hibernate: insert into EMPLOYEE_MEETING (EMPLOYEE_ID, MEETING_ID, OPINION) values (?, ?, ?)
Hibernate: insert into EMPLOYEE_MEETING (EMPLOYEE_ID, MEETING_ID, OPINION) values (?, ?, ?)
Hibernate: insert into EMPLOYEE_MEETING (EMPLOYEE_ID, MEETING_ID, OPINION) values (?, ?, ?)

---

我使用的是Hibernate 3.2.6，我已经编写了一些junits，一切都很好-我在employee_会议桌的数据库中看到：empId、meetID、意见：'17'、'7'、'BETTER'17'、'11'、'NICE'17'、'12'、'NICE'17'、'13'、'NICE'18'、'7'，“XX”`您会在映射中具体更改什么？您知道有没有任何示例可以使用附加属性（如意见）对多对多进行建模，但不为employee_meeting table创建单独的XML映射？

Employee e2 = (Employee) session.load(Employee.class, new Long(18));
    Employee e = (Employee) session.load(Employee.class, new Long(17));
    Iterator i = e.getMeetings().iterator();
    while (i.hasNext()){
        System.out.println(((EmployeeMeeting) i.next()).getMeeting().getMeetingId());
    }
    System.out.println(e2.getMeetings().iterator().next().getMeeting().getMeetingId());

    session.getTransaction().commit();
    session.close();

 Hibernate: select employee0_.EMPLOYEE_ID as EMPLOYEE1_0_0_, employee0_.firstname as     firstname0_0_, employee0_.lastname as lastname0_0_ from EMPLOYEE employee0_ where     employee0_.EMPLOYEE_ID=?
 Hibernate: select meetings0_.EMPLOYEE_ID as EMPLOYEE1_0_, meetings0_.MEETING_ID as      MEETING2_0_, meetings0_.OPINION as OPINION0_ from EMPLOYEE_MEETING meetings0_           where meetings0_.EMPLOYEE_ID=?
 Hibernate: select employee0_.EMPLOYEE_ID as EMPLOYEE1_0_0_, employee0_.firstname as firstname0_0_, employee0_.lastname as lastname0_0_ from EMPLOYEE employee0_ where employee0_.EMPLOYEE_ID=?
 Hibernate: select meetings0_.EMPLOYEE_ID as EMPLOYEE1_0_, meetings0_.MEETING_ID as MEETING2_0_, meetings0_.OPINION as OPINION0_ from EMPLOYEE_MEETING meetings0_ where meetings0_.EMPLOYEE_ID=?
12
11
7
13
7
Hibernate: delete from EMPLOYEE_MEETING where EMPLOYEE_ID=? and MEETING_ID=?
Hibernate: insert into EMPLOYEE_MEETING (EMPLOYEE_ID, MEETING_ID, OPINION) values (?, ?, ?)
Hibernate: delete from EMPLOYEE_MEETING where EMPLOYEE_ID=? and MEETING_ID=?
Hibernate: delete from EMPLOYEE_MEETING where EMPLOYEE_ID=? and MEETING_ID=?
Hibernate: delete from EMPLOYEE_MEETING where EMPLOYEE_ID=? and MEETING_ID=?
Hibernate: delete from EMPLOYEE_MEETING where EMPLOYEE_ID=? and MEETING_ID=?
Hibernate: insert into EMPLOYEE_MEETING (EMPLOYEE_ID, MEETING_ID, OPINION) values (?,   ?, ?)
Hibernate: insert into EMPLOYEE_MEETING (EMPLOYEE_ID, MEETING_ID, OPINION) values (?, ?, ?)
Hibernate: insert into EMPLOYEE_MEETING (EMPLOYEE_ID, MEETING_ID, OPINION) values (?, ?, ?)
Hibernate: insert into EMPLOYEE_MEETING (EMPLOYEE_ID, MEETING_ID, OPINION) values (?, ?, ?)