1. Spring依赖注入枚举值、常量
2. 构造器注入、Setter注入效果相同
3. 利用FieldRetrievingFactoryBean实现
4. xml配置方式

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:util="http://www.springframework.org/schema/util"
    xsi:schemaLocation="
        http://www.springframework.org/schema/beans https://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/util https://www.springframework.org/schema/util/spring-util.xsd">
        
	<bean id="demoTimeUnit1" class="test.DemoTimeUnit">
		<property name="time" value="60"/>
		<!-- 注入枚举值 -->
		<property name="timeUnit">
			<bean id="java.util.concurrent.TimeUnit.SECONDS"
				class="org.springframework.beans.factory.config.FieldRetrievingFactoryBean" />
		</property>
	</bean>
	
	<bean id="demoTimeUnit2" class="test.DemoTimeUnit">
    <property name="time" value="1"/>
    <!-- 注入枚举值 -->
    <property name="timeUnit">
      <util:constant static-field="java.util.concurrent.TimeUnit.MINUTES"/>
    </property>
  </bean>
</beans>

5. 执行效果
   
6. 详细说明查见Spring文档
   https://docs.spring.io/spring-framework/docs/current/reference/html/core.html#xsd-schemas-util-constant