在这篇文章中，我们将介绍如何使用Spring EL从 Map 和 List 中获得值。事实上，使用SpEL与 Map 和 List 的工作方式与Java是完全一样的。请参阅例如：
//get map whete key = 'MapA'
@Value("#{testBean.map['MapA']}")
private String mapA;
//get first value from list, list is 0-based.
@Value("#{testBean.list[0]}")
private String list;
Spring EL以注解的形式
在这里，创建了一个HashMap和ArrayList，并添加了一些初始测试数据。
package com.yiibai.core;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;
@Component("customerBean")
public class Customer {
@Value("#{testBean.map['MapA']}")
private String mapA;
@Value("#{testBean.list[0]}")
private String list;
public String getMapA() {
return mapA;
}
public void setMapA(String mapA) {
this.mapA = mapA;
}
public String getList() {
return list;
}
public void setList(String list) {
this.list = list;
}
@Override
public String toString() {
return "Customer [mapA=" + mapA + ", list=" + list + "]";
}
}
package com.yiibai.core;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import org.springframework.stereotype.Component;
@Component("testBean")
public class Test {
private Map<String, String> map;
private List<String> list;
public Test() {
map = new HashMap<String, String>();
map.put("MapA", "This is MapA");
map.put("MapB", "This is MapB");
map.put("MapC", "This is MapC");
list = new ArrayList<String>();
list.add("List0");
list.add("List1");
list.add("List2");
}
public Map<String, String> getMap() {
return map;
}
public void setMap(Map<String, String> map) {
this.map = map;
}
public List<String> getList() {
return list;
}
public void setList(List<String> list) {
this.list = list;
}
}
执行程序
Customer obj = (Customer) context.getBean("customerBean");
System.out.println(obj);
输出结果:
Customer [mapA=This is MapA, list=List0]
Spring EL以XML的形式
请参阅在XML文件定义bean的等效版本。
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans-3.0.xsd">
<bean id="customerBean" class="com.yiibai.core.Customer">
<property name="mapA" value="#{testBean.map['MapA']}" />
<property name="list" value="#{testBean.list[0]}" />
</bean>
<bean id="testBean" class="com.yiibai.core.Test" />
</beans>
