我正在尝试在我的 Spring MVC 项目中将 a 自动装配到我创建WebApplicationContext的类中。ImageCreatorUtil在使用应用程序上下文的类中执行方法时，我总是收到 NPE。需要注意的是，此方法是由ApplicationListener另一个配置文件中定义的调用。我不确定为什么自动装配不起作用。任何人都可以提供任何建议吗？
servlet-context.xml
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:mvc="http://www.springframework.org/schema/mvc" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:context="http://www.springframework.org/schema/context"
xsi:schemaLocation="http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-3.1.xsd
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-3.1.xsd">
<!-- DispatcherServlet Context: defines this servlet's request-processing
infrastructure -->
<!-- Enables the Spring MVC @Controller programming model -->
<mvc:annotation-driven>
<mvc:argument-resolvers>
<bean class="org.springframework.data.web.PageableArgumentResolver" />
</mvc:argument-resolvers>
</mvc:annotation-driven>
<!-- Intercept request to blog to add paging params -->
<mvc:interceptors>
<mvc:interceptor>
<mvc:mapping path="/blog/**"/>
<bean class="org.tothought.spring.interceptors.PageableRequestHandlerInterceptor" />
</mvc:interceptor>
<mvc:interceptor>
<mvc:mapping path="/**"/>
<bean class="org.tothought.spring.interceptors.LookupHandlerInterceptor" />
</mvc:interceptor>
</mvc:interceptors>
<!-- Handles HTTP GET requests for /resources/** by efficiently serving
up static resources in the ${webappRoot}/resources directory -->
<mvc:resources location="/resources/" mapping="/resources/**" />
<!-- Resolves views selected for rendering by @Controllers to .jsp resources
in the /WEB-INF/views directory -->
<bean
class="org.springframework.web.servlet.view.InternalResourceViewResolver">
<property name="prefix" value="/WEB-INF/views/" />
<property name="suffix" value=".jsp" />
</bean>
<bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
<property name="maxUploadSize" value="5000000"/>
</bean>
<context:component-scan base-package="org.tothought.spring.**" />
</beans>
ImageCreatorUtil.java
@Component
public class ImageCreatorUtil {
static Logger logger = LoggerFactory.getLogger(ImageCreatorUtil.class);
static final String IMAGE_PATH_FRAGMENT = "/resources/images/resume/skills/uploaded-icons/";
@Autowired
private WebApplicationContext context;
/**
* Creates the provided file in the resources directory for access by the
* web application.
*
* @param appContext
* @param image
*/
public void storeImage(Image image) {
if (image != null) {
String realPath = ((WebApplicationContext)context).getServletContext().getRealPath("/");
File tmpFile = new File(realPath + IMAGE_PATH_FRAGMENT + image.getName());
try {
logger.info("Saving image to :" + tmpFile.getAbsolutePath());
FileUtils.writeByteArrayToFile(tmpFile, image.getFile());
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
应用程序上下文.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" xmlns:jpa="http://www.springframework.org/schema/data/jpa"
xmlns:context="http://www.springframework.org/schema/context"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/data/jpa http://www.springframework.org/schema/data/jpa/spring-jpa-1.1.xsd
http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.1.xsd">
<context:property-placeholder location="classpath:META-INF/db/db.properties" />
<context:annotation-config/>
<bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource"
destroy-method="close">
<property name="driverClassName" value="com.mysql.jdbc.Driver" />
<property name="url" value="jdbc:mysql://localhost:3306/to_thought" />
<property name="username" value="${db.user}" />
<property name="password" value="${db.password}" />
</bean>
<bean id="entityManagerFactory"
class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
<property name="dataSource" ref="dataSource" />
<property name="persistenceUnitName" value="toThought" />
</bean>
<bean id="transactionManager" class="org.springframework.orm.jpa.JpaTransactionManager">
<property name="entityManagerFactory" ref="entityManagerFactory" />
</bean>
<jpa:repositories base-package="org.tothought.repositories"/>
<!-- Application Listeners -->
<bean id="lookupLoader" class="org.tothought.spring.listeners.LookupLoaderApplicationListener" />
<bean id="imageLoader" class="org.tothought.spring.listeners.ImageLoaderApplicationListener" />
</beans>
控制台错误
SEVERE: Exception sending context initialized event to listener instance of class org.springframework.web.context.ContextLoaderListener
java.lang.NullPointerException
at org.tothought.spring.utilities.ImageCreatorUtil.storeImage(ImageCreatorUtil.java:34)
at org.tothought.spring.listeners.ImageLoaderApplicationListener.onApplicationEvent(ImageLoaderApplicationListener.java:29)
at org.tothought.spring.listeners.ImageLoaderApplicationListener.onApplicationEvent(ImageLoaderApplicationListener.java:1)
at org.springframework.context.event.SimpleApplicationEventMulticaster.multicastEvent(SimpleApplicationEventMulticaster.java:97)
at org.springframework.context.support.AbstractApplicationContext.publishEvent(AbstractApplicationContext.java:324)