入门 10 - 集合对象注入

对于像数组、java.util.List、java.util.Set、java.util.Map等集合对象，在注入前必须填充入一些对象至集合中，然后再将集合对象注入至所需的Bean中，例如若有个Bean如下：

SomeBean.java

public class SomeBean {

    private String[] someStrArray;

    private SomeObj[] someObjArray;

    private List someList;

    private Map someMap;

    ....

 

}

对于这个需求，Spring也可以帮您维护，直接来看Bean定义档如何设定：

<beans>

    <bean id="someBean" class="onlyfun.caterpillar.SomeBean">

        <property name="someArray">

            <list>

                <value>Hello!Justin!</value>

                <value>Hello!Momor!</value>

                <value>Hello!Bush!</value>

            </list>

        </property>

        <property name="someObjArray">

            <list>

                <ref bean="someObj1"/>

                <ref bean="someObj2"/>

            </list>

        </property>

        <property name="someList">

            <list>

                 <value>Hello!Justin!</value>

                 <ref bean="someObj1"/>

                 <ref bean="someObj2"/>

            </list>

        </property>

        <property name="someMap">

            <map>

                 <entry key="somekey1">

                     <ref bean="someObj1"/>

                 </entry>

                 <entry key="somekey2">

                     <value>Hello!Justin!</value>

                 </entry>

            </map>

        </property>

    </bean>

</beans>

 

上面的Bean定义文件是个综合示范，数组与List对象都是用<list>卷标来设定，而Map对象使用<map>卷标设定，并需要一个key值设定。

Set的使用<set>标签，例如：

<set>

    <value>a set element</value>

        <ref bean="otherBean"/>

        <ref bean="anotherBean"/>

</set>

您也可以注入java.util.Properties，Bean定义档的写法示范如下：

....

    <bean id=....>

        ....

        <property name="someProperties">

            <props>

                <prop key="someProkey1">

                    someProValue1

                </prop>

                <prop key="someProkey2">

                    someProValue2

                </prop>

            </props>

        </property>

    </bean>

....