spring xml <property> 中的多个 <ref>

Question

我是 spring 新手，我有三个 bean id，例如 answerBean1、answerBean2、answerBean3，应该使用 <property> 将它们包含在 bean questionBean 中。我能够将一个 bean 分配为 ref，但是当分配多个 bean 时，我收到错误。我不需要为这项工作使用 <constuctor-arg>。

<bean id="answerBean1" class="com.spring.java.CICollection.Answer">
<property name="id" value="101"></property>
<property name="answerText" value="Collection of constants and method declarations"></property>
</bean>

<bean id="answerBean2" class="com.spring.java.CICollection.Answer">
<property name="id" value="102"></property>
<property name="answerText" value="Collection of abstract method and constants"></property>
</bean>

<bean id="answerBean3" class="com.spring.java.CICollection.Answer">
<property name="id" value="103"></property>
<property name="answerText" value="Constants and abstract methods"></property>
</bean>

<bean id="questionBean" class="com.spring.java.CICollection.Question">
<property name="id" value="101"></property>
<property name="questionText" value="What is interface?"></property>
<property name="answerList" >
<ref bean="answerBean1"/>
 <ref bean="answerBean2"/>
<ref bean="answerBean3"/>
</property>
</bean>

Answer 1

如评论中所述，如果 answerList 的类型为 java.util.List，则应将 bean 引用放在 <list> 标记内。其他包装器元素分别为 <set>、<map> 和 <props>，用于 java.util.Set、java.util.Map 和 java.util.Properties。查看 these examples 了解更多信息。

<bean id="questionBean" class="com.spring.java.CICollection.Question">
    <property name="id" value="101"></property>
    <property name="questionText" value="What is interface?"></property>
    <property name="answerList" >
        <list>
            <ref bean="answerBean1"/>
            <ref bean="answerBean2"/>
            <ref bean="answerBean3"/>
        <list>
    </property>
</bean>

Answer 2

如果您的 answerList 是列表类型，那么您应该只将多个 ref 放在列表标签中。就像下面的代码-

<bean id="questionBean" class="com.spring.java.CICollection.Question">
<property name="id" value="101"></property>
<property name="questionText" value="What is interface?"></property>
<property name="answerList">
    <list>
        <ref bean="answerBean1"/>
        <ref bean="answerBean2"/>
        <ref bean="answerBean3"/>
    </list>
</property>

...

</bean>

spring xml <property> 中的多个 <ref>

multiple <ref> in <property> in spring xml

java

xml

spring

spring-mvc

jakarta-ee