[SPRING] Autowired Null 포인터 예외

Autowired Null 포인터 예외

DB에 요청을 저장하는 필터가 있습니다. 하지만 autowired 필드 인 NullPointerException : inboundRequestLogStore가 발생합니다.

필자는 Filter Bean 클래스에서 Bean을 사용하여 제안을 시도 했습니까? (SpringBeanAutowiringSupport.processInjectionBasedOnServletContext (this, filterConfig.getServletContext ());를 필터 init 메소드에 추가하고 내 root-context.xml에 bean을 정의하고 이제는 RequestLogFilter 클래스에서 작동합니다. 하지만, InboundRequestLogStore 클래스에서 필자는 다른 엔터티를 DB에 저장하기 위해 autowired 된 logService를 가지고 있습니다. 그리고 지금이 시점에서 NullPointerEception을 얻습니다. 왜 NPE를 사용하고 어떻게 해결해야합니까? 내 프로젝트의 다른 부분에 동일한 서비스 / 구성 요소가 있으며 문제없이 서비스를 제공합니다. 필터 만 사용하는 데 문제가 있습니다.

@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);
            }
            }
    }
}

StackTrace

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" />

DelegatingFilterProxy를 사용하면 얻을 수 있습니다.

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)

을 포함한다.

<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>

root-context.xml

<bean id="inboundRequestLogStore" class="com.my.project.services.log.InboundRequestLogStore" />   
<bean id="requestLogFilter" class="com.my.project.config.filter.RequestLogFilter" />

구성 요소 (bean의 id로 표시)

@Component("inboundRequestLogStore")
public class InboundRequestLogStore implements InitializingBean {

-

@Component("requestLogFilter")
public class RequestLogFilter implements Filter {

RequestLogFilter에서 @Configurable이 작동하지 않습니다.

그 결과

이케트, 고마워!

몇몇 시도 후에 autowired 필드를 nullable로 만들지 못했습니다. 나는 root-context.xml에 bean을 추가했다.

<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>

클래스에서는이 같은 params 가진 생성자를 만들었습니다.

private LogServic logService;

public InboundRequestLogStore(LogServic logService) {
    this.logService = logService;
} ....

LogService에서

private EntityManagerFactory emf;

public void setEntityManagerFactory(EntityManagerFactory emf) {
    this.emf = emf;
}

그러나 DB에 내 엔티티를 저장하려고 할 때 아무 일도 일어나지 않았습니다. 일괄 삽입을 플러시하고 메모리를 해제하려고하면

entityManager.flush();
entityManager.clear();

그 다음 열지 않은 트랜잭션 (이와 같이, 나는 마음에 부를 수 없다) 예외가 발생했다.

나는 모든 것에 지쳤으며 요격기를 만들었습니다. 그리고 모든 것이 완벽하게 작동합니다. 누구든지 필터의 문제점을 설명 할 수 있다면 의견을 말하십시오.

웹

<?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>

해결법

1. ==============================

   1.대부분의 경우 서블릿 필터를 초기화 된 bean이 아닌 일반 Java 클래스로 초기화합니다.

   대부분의 경우 서블릿 필터를 초기화 된 bean이 아닌 일반 Java 클래스로 초기화합니다.

   DelegatingFilterProxy를 사용하십시오. 서블릿 필터로 스프링 빈을 사용하는 방법

   문서 https://dzone.com/articles/what-does-spring-delegatingfilterproxy-do를 확인하십시오.

from https://stackoverflow.com/questions/45231663/autowired-null-pointer-exception by cc-by-sa and MIT license