Question

我正在使用spring，使用hibernate和Mysql db。我有Question对象，它有一组Answer对象。

我的question.hbm.xml是

    <?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<!-- 
    Mapping file autogenerated by MyEclipse Persistence Tools
-->
<hibernate-mapping>
    <class name="com.gamesapp.model.Question" table="question" >
         <cache usage="read-write"/>
        <id name="questionId" type="java.lang.Long">
            <column name="question_id" />
            <generator class="identity" />
        </id>
        <property name="description" type="java.lang.String">
            <column name="description" length="500" not-null="true" />
        </property>
        <property name="difficultyLevel" type="java.lang.String">
            <column name="difficulty_level" length="6" not-null="true" />
        </property>
        <property name="isMixer" type="java.lang.String">
            <column name="is_mixer" length="5" not-null="true" />
        </property>
        <property name="status" type="java.lang.String">
            <column name="status" length="7" not-null="true" />
        </property>
        <set name="answers"  inverse="true"   >
         <cache usage="read-write"/>
            <key>
                <column name="question_id" not-null="true" />
            </key>
            <one-to-many class="com.gamesapp.model.Answer" />
        </set>

        <set name="questionAnswerUsers"  inverse="true" >
         <cache usage="read-write"/>
            <key>
                <column name="question_id" not-null="true" />
            </key>
            <one-to-many class="com.gamesapp.model.QuestionAnswerUser" />
        </set>
    </class>
</hibernate-mapping>

我的answer.hbm.xml是

    <?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<!-- 
    Mapping file autogenerated by MyEclipse Persistence Tools
-->
<hibernate-mapping>
    <class name="com.gamesapp.model.Answer" table="answer" >
       <cache usage="read-write"/>
        <id name="answerId" type="java.lang.Long">
            <column name="answer_id" />
            <generator class="identity" />
        </id>
        <many-to-one name="question" class="com.gamesapp.model.Question" fetch="select">
            <column name="question_id" not-null="true" />
        </many-to-one>
        <property name="description" type="java.lang.String">
            <column name="description" length="100" not-null="true" />
        </property>
        <property name="dragPosition" type="java.lang.Short">
            <column name="drag_position" />
        </property>
        <property name="orderSequence" type="java.lang.Integer">
            <column name="order_sequence" not-null="true" />
        </property>
        <property name="isAnswer" type="java.lang.String">
            <column name="is_answer" length="5" not-null="true" />
        </property>

        <property name="askPercentage" type="java.lang.Double">
            <column name="ask_percentage"  not-null="true" />
        </property>
        <set name="questionAnswerUsers"  inverse="true">
           <cache usage="read-write"/>
            <key>
                <column name="answer_id" not-null="true" />
            </key>
            <one-to-many class="com.gamesapp.model.QuestionAnswerUser" />
        </set>
    </class>
</hibernate-mapping>

现在我的问题是，我想以随机顺序获取问题列表。对于每个Question对象，我都希望使用hibernate标准来获取答案集，并且答案集也应该随机初始化。

例如说问题对象questionOne有一组答案有四个Answer object.say ans1，ans2，ans3和ans4。现在我第一次获取questionOne时，应该将answer设置为answer = {ans1，ans2，ans3，ans4}。第二次我获取questionOne对象我应该得到答案设置为answer = {ans4，ans2，ans3，ans1}。

问题清单应随机初始化。永远问题的答案集应该使用休眠标准来获取，每次都应该洗牌。

提前致谢。

Answer 1

只需使用Collections.shuffle()获取随机列表：

List<Question> questions = em.createQuery(...).getResultList();
Collections.shuffle(questions);

在问题实体中：

public List<Answer> getShuffledAnswers() {
    List<Answer> result = new ArrayList<Answer>(this.answers);
    Collections.shuffle(result);
    return result;
}

使用hibernate以随机顺序初始化集合对象

1 个答案: