控制层@Value注解取不到值
@Value("${enable-upload-image}") private String enable;
如上所示,同样的代码,写在在业务层,运行时能取到正确的值,但在控制层却取得了@Value注解中的Key(@Value注解有个特点,如果取不到值,那么不是返回一个null,而是返回Key)。
原因是controller注册在dispatcherservlet-servlet.xml代表的Spring MVC的容器中,而service则注册在application-context.xml代表的Spring的容器中。
如果context:property-placeholder只注册在Spring的容器中,那么自然只有业务层的类可以取到enable-upload-image的值,而控制器取不到值。
解决方法就是把各种context:property-placeholder在两个容器中都注册一下。如:
spring-properties.xml
<?xml version="1.0" encoding="UTF-8" ?> <beans xmlns="http://www.springframework.org/schema/beans" xmlns:context="http://www.springframework.org/schema/context" 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.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd"> <context:property-placeholder location="classpath:wechat/official-account.properties" ignore-unresolvable="true" /> <context:property-placeholder location="classpath:conf.properties" ignore-unresolvable="true" /> <context:property-placeholder location="classpath:copywriting.properties" ignore-unresolvable="true" /> </beans>
application-context.xml
<?xml version="1.0" encoding="UTF-8" ?> <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.xsd"> <import resource="classpath:springframework/spring-*.xml" /> </beans>
dispatcherservlet-servlet.xml
<beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:context="http://www.springframework.org/schema/context" xmlns:mvc="http://www.springframework.org/schema/mvc" xmlns:aop="http://www.springframework.org/schema/aop" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc.xsd http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop.xsd"> <!-- 其他配置忽略 --> <import resource="classpath:springframework/spring-properties.xml" /> </beans>