Hibernate双向关联插入数据时候的怪问题

简单描述一下表结构：主表Team，从表Player，建立外键关联。

以下是HBM文件：

Team：

<hibernate-mapping></hibernate-mapping>

xml 代码

<hibernate-mapping>
    <class name="com.hibernatedemo.model.Team" table="team" catalog="hibernatedemo">
        <comment></comment>
        <id name="id" type="string">
            <column name="id" length="32" />
            <generator class="assigned" />
        </id>
        <property name="name" type="string">
            <column name="name" length="32" not-null="true">
                <comment></comment>
            </column>
        </property>
        <set name="players" inverse="true" cascade="all">
            <key>
                <column name="team" length="32" not-null="true">
                    <comment></comment>
                </column>
            </key>
            <one-to-many class="com.hibernatedemo.model.Player" />
        </set>
    </class>
</hibernate-mapping>

Palyer：

<hibernate-mapping></hibernate-mapping>

xml 代码

<hibernate-mapping>
    <class name="com.hibernatedemo.model.Player" table="player" catalog="hibernatedemo">
        <comment></comment>
        <id name="id" type="string">
            <column name="id" length="32" />
            <generator class="assigned" />
        </id>
        <many-to-one name="team" class="com.hibernatedemo.model.Team" fetch="select">
            <column name="team" length="32" not-null="true">
                <comment></comment>
            </column>
        </many-to-one>
        <property name="name" type="string">
            <column name="name" length="32" not-null="true">
                <comment></comment>
            </column>
        </property>
        <property name="gender" type="java.lang.Boolean">
            <column name="gender">
                <comment></comment>
            </column>
        </property>
        <property name="birthday" type="date">
            <column name="birthday" length="10">
                <comment></comment>
            </column>
        </property>
    </class>
</hibernate-mapping>

 

插入数据的代码如下：

java 代码

Transaction tx = session.beginTransaction();
        for(int i=0;i<2;i++) {
            Team team = new Team();
            team.setId("Team" + new Integer(i).toString());
            team.setName(team.getId());
            Set
    <player></player>
     players = new HashSet
    <player></player>
    ();
            for(int j=0;j<10;j++) {
                Player player = new Player();
                player.setId("Player" + team.getId()+"."+new Integer(j).toString());
                player.setName(player.getId());
                player.setBirthday(new Date());
                player.setGender(true);
                player.setTeam(team);
                players.add(player);
            }
            team.setPlayers(players);
            session.save(team);
        }
        tx.commit();

 

执行代码，SQL打印如下：

Hibernate: select player_.id, player_.team as team1_, player_.name as name1_, player_.gender as gender1_, player_.birthday as birthday1_ from hibernatedemo.player player_ where player_.id=?
Hibernate: select player_.id, player_.team as team1_, player_.name as name1_, player_.gender as gender1_, player_.birthday as birthday1_ from hibernatedemo.player player_ where player_.id=?
Hibernate: select player_.id, player_.team as team1_, player_.name as name1_, player_.gender as gender1_, player_.birthday as birthday1_ from hibernatedemo.player player_ where player_.id=?
Hibernate: select player_.id, player_.team as team1_, player_.name as name1_, player_.gender as gender1_, player_.birthday as birthday1_ from hibernatedemo.player player_ where player_.id=?
Hibernate: select player_.id, player_.team as team1_, player_.name as name1_, player_.gender as gender1_, player_.birthday as birthday1_ from hibernatedemo.player player_ where player_.id=?
Hibernate: select player_.id, player_.team as team1_, player_.name as name1_, player_.gender as gender1_, player_.birthday as birthday1_ from hibernatedemo.player player_ where player_.id=?
Hibernate: select player_.id, player_.team as team1_, player_.name as name1_, player_.gender as gender1_, player_.birthday as birthday1_ from hibernatedemo.player player_ where player_.id=?
Hibernate: select player_.id, player_.team as team1_, player_.name as name1_, player_.gender as gender1_, player_.birthday as birthday1_ from hibernatedemo.player player_ where player_.id=?
Hibernate: select player_.id, player_.team as team1_, player_.name as name1_, player_.gender as gender1_, player_.birthday as birthday1_ from hibernatedemo.player player_ where player_.id=?
Hibernate: select player_.id, player_.team as team1_, player_.name as name1_, player_.gender as gender1_, player_.birthday as birthday1_ from hibernatedemo.player player_ where player_.id=?
Hibernate: select player_.id, player_.team as team1_, player_.name as name1_, player_.gender as gender1_, player_.birthday as birthday1_ from hibernatedemo.player player_ where player_.id=?
Hibernate: select player_.id, player_.team as team1_, player_.name as name1_, player_.gender as gender1_, player_.birthday as birthday1_ from hibernatedemo.player player_ where player_.id=?
Hibernate: select player_.id, player_.team as team1_, player_.name as name1_, player_.gender as gender1_, player_.birthday as birthday1_ from hibernatedemo.player player_ where player_.id=?
Hibernate: select player_.id, player_.team as team1_, player_.name as name1_, player_.gender as gender1_, player_.birthday as birthday1_ from hibernatedemo.player player_ where player_.id=?
Hibernate: select player_.id, player_.team as team1_, player_.name as name1_, player_.gender as gender1_, player_.birthday as birthday1_ from hibernatedemo.player player_ where player_.id=?
Hibernate: select player_.id, player_.team as team1_, player_.name as name1_, player_.gender as gender1_, player_.birthday as birthday1_ from hibernatedemo.player player_ where player_.id=?
Hibernate: select player_.id, player_.team as team1_, player_.name as name1_, player_.gender as gender1_, player_.birthday as birthday1_ from hibernatedemo.player player_ where player_.id=?
Hibernate: select player_.id, player_.team as team1_, player_.name as name1_, player_.gender as gender1_, player_.birthday as birthday1_ from hibernatedemo.player player_ where player_.id=?
Hibernate: select player_.id, player_.team as team1_, player_.name as name1_, player_.gender as gender1_, player_.birthday as birthday1_ from hibernatedemo.player player_ where player_.id=?
Hibernate: select player_.id, player_.team as team1_, player_.name as name1_, player_.gender as gender1_, player_.birthday as birthday1_ from hibernatedemo.player player_ where player_.id=?
Hibernate: insert into hibernatedemo.team (name, id) values (?, ?)
Hibernate: insert into hibernatedemo.player (team, name, gender, birthday, id) values (?, ?, ?, ?, ?)
Hibernate: insert into hibernatedemo.player (team, name, gender, birthday, id) values (?, ?, ?, ?, ?)
Hibernate: insert into hibernatedemo.player (team, name, gender, birthday, id) values (?, ?, ?, ?, ?)
Hibernate: insert into hibernatedemo.player (team, name, gender, birthday, id) values (?, ?, ?, ?, ?)
Hibernate: insert into hibernatedemo.player (team, name, gender, birthday, id) values (?, ?, ?, ?, ?)
Hibernate: insert into hibernatedemo.player (team, name, gender, birthday, id) values (?, ?, ?, ?, ?)
Hibernate: insert into hibernatedemo.player (team, name, gender, birthday, id) values (?, ?, ?, ?, ?)
Hibernate: insert into hibernatedemo.player (team, name, gender, birthday, id) values (?, ?, ?, ?, ?)
Hibernate: insert into hibernatedemo.player (team, name, gender, birthday, id) values (?, ?, ?, ?, ?)
Hibernate: insert into hibernatedemo.player (team, name, gender, birthday, id) values (?, ?, ?, ?, ?)
Hibernate: insert into hibernatedemo.team (name, id) values (?, ?)
Hibernate: insert into hibernatedemo.player (team, name, gender, birthday, id) values (?, ?, ?, ?, ?)
Hibernate: insert into hibernatedemo.player (team, name, gender, birthday, id) values (?, ?, ?, ?, ?)
Hibernate: insert into hibernatedemo.player (team, name, gender, birthday, id) values (?, ?, ?, ?, ?)
Hibernate: insert into hibernatedemo.player (team, name, gender, birthday, id) values (?, ?, ?, ?, ?)
Hibernate: insert into hibernatedemo.player (team, name, gender, birthday, id) values (?, ?, ?, ?, ?)
Hibernate: insert into hibernatedemo.player (team, name, gender, birthday, id) values (?, ?, ?, ?, ?)
Hibernate: insert into hibernatedemo.player (team, name, gender, birthday, id) values (?, ?, ?, ?, ?)
Hibernate: insert into hibernatedemo.player (team, name, gender, birthday, id) values (?, ?, ?, ?, ?)
Hibernate: insert into hibernatedemo.player (team, name, gender, birthday, id) values (?, ?, ?, ?, ?)
Hibernate: insert into hibernatedemo.player (team, name, gender, birthday, id) values (?, ?, ?, ?, ?)

 

问题是：为什么在insert语句之前，会执行select语句，对player进行查询呢？请指教

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关于Hibernate加载数据时的CGLIB动态代理 ... | 关于常量类使用的一个问题。

• 2007-09-17 10:22
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评论

2 楼 fangang 2007-10-09  

哈哈，你这个问题的关键就在“cascade="all"”，如果你这样设置了，你对集合做的所有操作都会反映到数据库操作中，这包括你做的“player.setTeam(team);”，导致了那个查询语句。

1 楼 johnnylzb 2007-09-29  

没人能回答吗？

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