java - 在@Service注释的类中使用@Value注入时获取空值,但能够在@Controller注释的类中获取值
问题描述
我在尝试使用 @Service 类注释的 clas 中的 @Value 注入时得到空值,但是我能够在由 @Service 注释的类中获取相同属性的值我使用的是 Spring 4.2 vesion
web.xml 如下:::
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns="http://xmlns.jcp.org/xml/ns/javaee"
xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd"
id="WebApp_ID" version="3.1">
<display-name></display-name>
<servlet>
<servlet-name>CaptchaServlet</servlet-name>
<servlet-class>com.cdac.sikkimSprings.servlets.CaptchaServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>CaptchaServlet</servlet-name>
<url-pattern>/captcha.jpg</url-pattern>
</servlet-mapping>
<servlet>
<servlet-name>SpringController</servlet-name>
<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
<init-param>
<param-name>contextConfigLocation</param-name>
<param-value>/WEB-INF/spring-mvc.xml</param-value>
</init-param>
<load-on-startup>1</load-on-startup>
</servlet>
<servlet-mapping>
<servlet-name>SpringController</servlet-name>
<url-pattern>/</url-pattern>
</servlet-mapping>
<listener>
<listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
</listener>
<context-param>
<param-name>contextConfigLocation</param-name>
<param-value>
/WEB-INF/beans.xml
/WEB-INF/spring-security.xml
</param-value>
</context-param>
<filter>
<filter-name>springSecurityFilterChain</filter-name>
<filter-class>org.springframework.web.filter.DelegatingFilterProxy</filter-class>
</filter>
<filter-mapping>
<filter-name>springSecurityFilterChain</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>
</web-app>
springMVC.xml 如下
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:context="http://www.springframework.org/schema/context"
xmlns:mvc="http://www.springframework.org/schema/mvc"
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-4.0.xsd
http://www.springframework.org/schema/beans/spring-beans-4.0.xsd
http://www.springframework.org/schema/mvc
http://www.springframework.org/schema/mvc
http://www.springframework.org/schema/mvc/spring-mvc-4.0.xsd
http://www.springframework.org/schema/mvc/spring-mvc-4.0.xsd
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context-4.0.xsd
http://www.springframework.org/schema/context/spring-context-4.0.xsd">
<context:component-scan base-package="com.basePackage" />
<mvc:annotation-driven />
<mvc:resources mapping="/resources/**" location="/resources/" />
<bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
<property name="prefix" value="/WEB-INF/views/" />
<property name="suffix" value=".jsp" />
</bean>
<context:property-placeholder location="classpath:properties/development.properties" order="1"/>
<bean id="multipartResolver"
class="org.springframework.web.multipart.commons.CommonsMultipartResolver"/>
</beans>
我也有 beans.xml 用于 bean 定义,如下所示
<?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:context="http://www.springframework.org/schema/context"
xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans-4.0.xsd
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context-4.0.xsd">
<!-- <bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource">
<property name="driverClassName" value="com.mysql.jdbc.Driver" /> <property
name="url" value="jdbc:mysql://localhost:3306/test" /> <property name="username"
value="root" /> <property name="password" value="password" /> </bean> -->
//下面提到的Bean定义是我需要注入属性值的同一个类,由@Service注解注解
<bean id="userManagement"
class="com.basepackage.userManagement">
</bean>
</beans>
下面是需要注入值的实际java类
@Service("userManagementService")
@Transactional
public class userManagement implements RetrieveUserListService{
//This value is not getting injected
@Value("${registrationstatus_registered}")
String statusRegistered;
@Value("${registrationstatus_pending}")
String statusPending;
@Override
public List<ShowUserListPOJO> RetrieveUserList(HttpServletRequest request, HttpServletResponse response) {
// TODO Auto-generated method stub
//here the required value is null
System.out.println(statusRegistered);
return null;
}
//Code bellow is skipped...
我在下面的类中注入相同的值,它们被正确注入
@Controller
public class UserManagement {
@Value( "${registrationstatus_registered}" )
String registrationstatus;
@RequestMapping(value="/userManagement", method = RequestMethod.GET)
public void userManagement(HttpServletRequest request,HttpServletResponse response) {
//here value is prnted properly
System.out.println(registrationstatus);
//......Code below skipped
}
development.properties 如下
registrationstatus_registered = registered
registrationstatus_pending = pending
解决方案
在您的应用程序中,您有两个 Spring 上下文:根应用程序上下文 ( ContextLoaderListener
) 和 Web 应用程序上下文( DispatcherServlet
)。您需要了解它们之间的区别。在这里阅读。如果您将属性资源定义移动到 beans.xml(用于根上下文),您的属性值将在整个应用程序中正确注入。
将此 bean 定义移动到 beans.xml
<context:property-placeholder location="classpath:properties/development.properties" order="1"/>
。
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