作用:主要用于框架整合配置。
java.utils包中常用的集合有:
- List
- Set
- Map
- Properties
Spring为集合提供了对应的标签:
- 注入 list元素
- 注入 set元素
- 注入 properties 元素 (hashtable类的子类,其实就是一个特殊的map,key和value都是String )
示例:
实体类:
//注入集合类型的属性
public class CollectionBean {
private List<String> list; .
private Set<Integer> set;
private Map<String, String> map;
private Properties properties;
public void setlist(List<String> 1ist) {
this.list = list; .
}
public void setSset(Set<Integer> set) {
this.set = set;
}
public void setMap(Map<String, String> map) {
this.map = map;
}
pub1ic void setProperties(Properties properties) {
this. properties = properties;
}
@override
public String toString() {
return "CollectionBean [list=" + list + ",set="+ set + ", map=" + map
+”, properties-" + properties + "]";
}
}
applicatioContext.xml
<I-- 集合类型的属性注入-->
<bean name= "collectionBean" class="cn. itcast. spring.e_ di. Col lectionBean">
<property name= "list">
<!-- 注入list -->
<list>
<!--
value注入简单类型
ref注入引用的复杂类型
-->
<value>aa</value>
<value>bb</value>
<value>cc</value>
<value>dd</value>
<!-- <ref bean="car"/> -->
</list>
</property>
<!--注入set -->
<property name= "set">
<set>
<value>11</value>
<value>22</value>
<value>11</value>
<value>22</value>
</set>
</property>
<!--注入map -->
<property name- “map">
<map>
<entry. key= "aa" value="11"/>
<entry key="bb" >
<value>22</value>
</entry>
</map>
</property>
<!--注入properties -->.
<property name=' "properties">
<props>
<prop key= "p1"*>pp1</prop>
<prop key=“p2">pp2</prop>
<prop key="name ">张三</prop>
</props>
</property>
</bean>
注意:property注入的key不能重复,重复只能打印一个值