我有一个过滤器来保存对DB的请求。但是我在autowired字段上得到NullPointerException：inboundRequestLogStore。
我已经尝试了Using some beans in Filter bean class? (I've added SpringBeanAutowiringSupport.processInjectionBasedOnServletContext(this, filterConfig.getServletContext()); to the filter init method and defined a bean in my root-context.xml )的建议，现在它适用于RequestLogFilter类。但是，在InboundRequestLogStore类中，我有另一个自动装配的logService来将我的实体保存到DB，现在我得到了NullPointerEception。为什么我有NPE以及如何解决它？我在项目的其他部分有相同的服务/组件，他们自动服务服务没有任何问题。我只是使用过滤器而遇到麻烦。
@Component
public class RequestLogFilter implements Filter {
@Autowired
private InboundRequestLogStore inboundRequestLogStore;
public RequestLogFilter() {
}
@Override
public void init(FilterConfig filterConfig) throws ServletException {
SpringBeanAutowiringSupport.processInjectionBasedOnServletContext(this, filterConfig.getServletContext());
}
public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
HttpServletRequest requestToCache = new ContentCachingRequestWrapper((HttpServletRequest) request);
HttpServletResponseCopier responseCopier = new HttpServletResponseCopier((HttpServletResponse) response);
chain.doFilter(request, responseCopier);
responseCopier.flushBuffer();
if (request.getAttribute(InboundRequestAspect.INBOUND_LOG_MARKER) != null) {
InboundRequestLogRecord logRecord = new InboundRequestLogRecord();
setters....
inboundRequestLogStore.add(logRecord);
}
}
}
-
@Component("inboundRequestLogStore")
public class InboundRequestLogStore implements InitializingBean {
private ConcurrentLinkedQueue<InboundRequestLogRecord> queue = new ConcurrentLinkedQueue<>();
@Autowired
private LogService logService;
@Override
public void afterPropertiesSet() throws Exception {
reseterPool = new ScheduledThreadPoolExecutor(1);
reseterPool.scheduleWithFixedDelay(new LogRequestSaveQueueTask(), startupDelay, sleepTimeout, TimeUnit.SECONDS);
}
public InboundRequestLogStore() {
}
public void add(InboundRequestLogRecord logRequest) {
queue.add(logRequest);
}
private class LogRequestSaveQueueTask implements Runnable {
@Override
public void run() {
try {
if (queue.size() > 0) {
List<InboundRequestLogRecord> logRequestList = new ArrayList<>();
InboundRequestLogRecord obj;
while((obj = queue.poll()) != null) {
logRequestList.add(obj);
}
if (!logRequestList.isEmpty()) {
logService.save(logRequestList);
}
}
} catch(Exception e) {
logger.error(e.getMessage(), e);
}
}
}
}
栈跟踪
java.lang.NullPointerException: null
at com.my.project.services.log.InboundRequestLogStore$LogRequestSaveQueueTask.run(InboundRequestLogStore.java:71) [classes/:?]
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511) [?:1.8.0_131]
at java.util.concurrent.FutureTask.runAndReset(FutureTask.java:308) [?:1.8.0_131]
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$301(ScheduledThreadPoolExecutor.java:180) [?:1.8.0_131]
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:294) [?:1.8.0_131]
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) [?:1.8.0_131]
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617) [?:1.8.0_131]
at java.lang.Thread.run(Thread.java:748) [?:1.8.0_131]
-
<context:component-scan base-package="com.my.project" />
-
<bean id="inboundRequestLogStore" class="com.my.project.services.log.InboundRequestLogStore" />
如果使用DelegatingFilterProxy，那么我得到
SEVERE: Servlet.service() for servlet [appServlet] in context with path [] threw exception
java.lang.NullPointerException
at com.my.project.config.filter.RequestLogFilter.doFilter(RequestLogFilter.java:121)
at org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:346)
at org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:262)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:219)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:106)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:142)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79)
at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:616)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:88)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:518)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1091)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:673)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1526)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1482)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
at java.lang.Thread.run(Thread.java:748)
的web.xml
<filter>
<filter-name>requestLogFilter</filter-name>
<filter-class>org.springframework.web.filter.DelegatingFilterProxy</filter-class>
</filter>
<filter-mapping>
<filter-name>requestLogFilter</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>
根context.xml中
<bean id="inboundRequestLogStore" class="com.my.project.services.log.InboundRequestLogStore" />
<bean id="requestLogFilter" class="com.my.project.config.filter.RequestLogFilter" />
组件（标有bean＆＃39; id）
@Component("inboundRequestLogStore")
public class InboundRequestLogStore implements InitializingBean {
-
@Component("requestLogFilter")
public class RequestLogFilter implements Filter {
RequestLogFilter上的@Configurable无法正常工作。
结果
ikettu ，谢谢！
经过一些尝试，我已经实现了自动装配的字段不可为空。 我已将bean添加到root-context.xml<bean id="requestLogFilter" class="com.my.project.config.filter.RequestLogFilter">
<constructor-arg ref="inboundRequestLogStore"/>
</bean>
<bean id="inboundRequestLogStore" class="com.my.project.service.InboundRequestLogStore">
<constructor-arg ref="logService"/>
</bean>
<bean id="logService" class="com.my.project.service.LogService">
<constructor-arg ref="entityManagerFactory"/>
</bean>
在课程中，我创建了带有这样的参数的构造函数
private LogServic logService;
public InboundRequestLogStore(LogServic logService) {
this.logService = logService;
} ....
在LogService中
private EntityManagerFactory emf;
public void setEntityManagerFactory(EntityManagerFactory emf) {
this.emf = emf;
}
但是当我试图将我的实体保存到数据库时，没有发生任何事情。如果我试图刷新一批插入并释放内存
entityManager.flush();
entityManager.clear();
然后NotOpenedTransaction（像这样，我无法想到）异常已经发生
我厌倦了所有人，并创造了一个拦截器。所有的作品都很有趣。如果有人能解释过滤器的问题，请发表评论。
Web.xml中
<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5" xmlns="http://java.sun.com/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">
<!-- The definition of the Root Spring Container shared by all Servlets and Filters -->
<context-param>
<param-name>contextConfigLocation</param-name>
<param-value>/WEB-INF/spring/root-context.xml</param-value>
</context-param>
<!-- Creates the Spring Container shared by all Servlets and Filters -->
<listener>
<listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
</listener>
<!-- Processes application requests -->
<servlet>
<servlet-name>appServlet</servlet-name>
<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
<init-param>
<param-name>contextConfigLocation</param-name>
<param-value>/WEB-INF/spring/appServlet/servlet-context.xml</param-value>
</init-param>
<load-on-startup>1</load-on-startup>
</servlet>
<servlet-mapping>
<servlet-name>appServlet</servlet-name>
<url-pattern>/</url-pattern>
</servlet-mapping>
<!-- <filter> -->
<!-- <filter-name>requestLogFilter</filter-name> -->
<!-- <filter-class>org.springframework.web.filter.DelegatingFilterProxy</filter-class> -->
<!-- if set this parameter to true then filter init & destroy methods will be called -->
<!-- <init-param> -->
<!-- <param-name>targetFilterLifecycle</param-name> -->
<!-- <param-value>true</param-value> -->
<!-- </init-param> -->
<!-- </filter> -->
<!-- <filter-mapping> -->
<!-- <filter-name>requestLogFilter</filter-name> -->
<!-- <url-pattern>/*</url-pattern> -->
<!-- </filter-mapping> -->
</web-app>
答案 0 :(得分：0)
很可能你现在将servlet过滤器初始化为普通的java类而不是初始化的bean。
请使用DelegatingFilterProxy 将春豆作为serlvet过滤器
检查文章https://dzone.com/articles/what-does-spring-delegatingfilterproxy-do