使用AspectJ风格的Spring AOP的请求范围内的bean的空指针异常（@Around建议@Transactional Webservice方法）

Question

我正在使用Spring 3.1.0.RC1。 我有一个基于Apache CXF的Web服务。 我试图建议每个@Transactional带注释的服务方法。

我有一些“周围”建议的方面。 在方法内部，我将数据存储到请求范围内的事务有效负载bean中。 稍后，我在另一个单例作用域的bean中从此有效载荷中请求uuid。 结果是空指针异常。

Caused by: java.lang.RuntimeException: java.lang.NullPointerException
    at com.spp.mui.jaxws.service.virtual._0_1.VirtualWebService.postOfferSet(VirtualWebService.java:209)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    at java.lang.reflect.Method.invoke(Method.java:597)
    at org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:309)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.invokeJoinpoint(ReflectiveMethodInvocation.java:183)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:150)
    at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:110)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172)
    at org.springframework.aop.aspectj.MethodInvocationProceedingJoinPoint.proceed(MethodInvocationProceedingJoinPoint.java:80)
    at com.spp.mui.aop.tx.NewAgeTransactionLoggingAspect.logTransaction(NewAgeTransactionLoggingAspect.java:85)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    at java.lang.reflect.Method.invoke(Method.java:597)
    at org.springframework.aop.aspectj.AbstractAspectJAdvice.invokeAdviceMethodWithGivenArgs(AbstractAspectJAdvice.java:621)
    at org.springframework.aop.aspectj.AbstractAspectJAdvice.invokeAdviceMethod(AbstractAspectJAdvice.java:610)
    at org.springframework.aop.aspectj.AspectJAroundAdvice.invoke(AspectJAroundAdvice.java:65)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:161)
    at org.springframework.aop.aspectj.MethodInvocationProceedingJoinPoint.proceed(MethodInvocationProceedingJoinPoint.java:80)
    at com.spp.mui.aop.ws.TraceWebServiceMethodAspect.invoke(TraceWebServiceMethodAspect.java:68)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    at java.lang.reflect.Method.invoke(Method.java:597)
    at org.springframework.aop.aspectj.AbstractAspectJAdvice.invokeAdviceMethodWithGivenArgs(AbstractAspectJAdvice.java:621)
    at org.springframework.aop.aspectj.AbstractAspectJAdvice.invokeAdviceMethod(AbstractAspectJAdvice.java:610)
    at org.springframework.aop.aspectj.AspectJAroundAdvice.invoke(AspectJAroundAdvice.java:65)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172)
    at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:90)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172)
    at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:202)
    at $Proxy95.postOfferSet(Unknown Source)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    at java.lang.reflect.Method.invoke(Method.java:597)
    at org.apache.cxf.service.invoker.AbstractInvoker.performInvocation(AbstractInvoker.java:173)
    at org.apache.cxf.service.invoker.AbstractInvoker.invoke(AbstractInvoker.java:89)
    ... 49 more
Caused by: java.lang.NullPointerException
    at com.spp.mui.jaxws.agent.WSResponseAgent.getResponse(WSResponseAgent.java:28)
    at com.spp.mui.jaxws.agent.WSResponseAgent.getResponse(WSResponseAgent.java:18)
    at com.spp.mui.jaxws.handler.offer.PostVirtualOffersHandler.handle(PostVirtualOffersHandler.java:58)
    at com.spp.mui.jaxws.service.virtual._0_1.VirtualWebService.postOfferSet(VirtualWebService.java:205)
    ... 88 more

那么，此堆栈跟踪中发生了什么？

调用了Web服务方法（即postOfferSet）。 该方法是由具有@Around切入点的方面建议的。 该方法也带有@Transactional注释。

更新自此以来，我已将原始配置更新为基于Java的配置。 使用XML配置或Java配置时，都会遇到相同的问题。 我的Java配置是当前正在使用的配置，也是我想要帮助诊断的配置。 请向下滚动（向前跳）以查看下面的Java配置。 （对于其他新手，请继续阅读）。

我的方面配置看起来像

 <aop:aspectj-autoproxy />

 <bean id="newAgeTxLoggingAspect" class="com.spp.mui.aop.tx.NewAgeTransactionLoggingAspect">
    <property name="transactionLogService" ref="txLogServiceEngine" />
    <property name="securable" ref="securityAgent" />
    <property name="loggableTransactionToken" ref="loggableTransactionToken" />
    <property name="logQuery" value="${newAgeTxLoggingAspect.logQuery}" />
    <property name="logReply" value="${newAgeTxLoggingAspect.logReply}" />
    <property name="logSubmit" value="${newAgeTxLoggingAspect.logSubmit}" />
    <property name="maxReplySize" value="${newAgeTxLoggingAspect.maxReplySize}" />
    <property name="maxRequestSize" value="${newAgeTxLoggingAspect.maxRequestSize}" />
    <property name="order" value="5" />
</bean>

如前所述，loggableTransactionToken是请求范围的。

这是它的bean定义

<!-- 
    Request scoped bean that allows LoggableTransaction instances to be created and accessed on a single-thread of execution
    Consult http://static.springsource.org/spring/docs/3.0.x/spring-framework-reference/html/beans.html#beans-factory-scopes-other-injection 
-->
<bean id="loggableTransactionToken" class="com.spp.mui.commons.spring.LoggableTransactionToken" scope="request">
    <aop:scoped-proxy proxy-target-class="false"/>
</bean>

前面提到的Web服务方法委托给Handler

这是处理程序的摘录

 @Override
public ConfirmationType handle(OfferSetType request) {
    // step 1: convert from JAXB type to domain objects
    List<MktVirtualOffer> candidateOffers = codecService.convert(request, List.class);
    ...
    // step 4: get response -- response encapsulates transaction id
    return responder.getResponse();
}

注意处理程序使用响应程序吗？

这是响应者（又名WSResponseAgent）的摘录

@Override
public ConfirmationType getResponse() {
    ConfirmationType response = new ConfirmationType();
    LoggableTransaction lt = token.getToken();
    response.setTransactionID(lt.getUuid());
    logger.debug(ReflectUtil.toString(lt));
    return response;
}

希望我已经提供了足够的帮助您帮助我了解为什么要获得NPE？

更新这是Java配置和其他暗示

AOP配置

@Configuration
@EnableAspectJAutoProxy
@Import(value = { LoggingConfig.class, AuthConfig.class })
public class AopConfig {

@Resource
private Environment env;

@Resource
private LoggingConfig loggingConfig;

@Resource
private AuthConfig authConfig;

/* Consult
 *   static.springsource.org/spring/docs/3.0.x/spring-framework-reference/html/transaction.html#transaction-declarative-applying-more-than-just-tx-advice
 *   and http://static.springsource.org/spring/docs/3.0.x/spring-framework-reference/html/aop.html#aop-ataspectj-advice-ordering
 */

@Bean
public NewAgeTransactionLoggingAspect txLoggingAspect() {
    NewAgeTransactionLoggingAspect aspect = new NewAgeTransactionLoggingAspect();
    aspect.setEnvironment(env);
    aspect.setLoggableTransactionToken(loggingConfig.loggableTxToken());
    aspect.setSecurable(authConfig.securable());
    aspect.setTransactionLogService(loggingConfig.txLogService());
    aspect.setLogQuery(Boolean.valueOf(env.getProperty("newAgeTxLoggingAspect.logQuery", Boolean.toString(true))));
    aspect.setLogReply(Boolean.valueOf(env.getProperty("newAgeTxLoggingAspect.logReply", Boolean.toString(true))));
    aspect.setLogSubmit(Boolean.valueOf(env.getProperty("newAgeTxLoggingAspect.logSubmit", Boolean.toString(true))));
    aspect.setMaxRequestSize(Integer.valueOf(env.getProperty("newAgeTxLoggingAspect.maxRequestSize", "100000000")));
    aspect.setMaxReplySize(Integer.valueOf(env.getProperty("newAgeTxLoggingAspect.maxReplySize", "100000000")));
    aspect.setOrder(Integer.valueOf(env.getProperty("newAgeTxLoggingAspect.order", "5")));
    return aspect;
}


}

这是配置文件中的片段，负责设置NewAgeTransactionLoggingService和LoggableTransactionToken

@Bean
public TransactionLogService txLogService() {
    HibernateTransactionLogService service = new HibernateTransactionLogService();
    service.setLogParameters(Boolean.valueOf(Boolean.toString(true)));
    service.setTimeDispatcher(timeConfig.timeDispatcher());
    service.setSessionFactory(sessionFactory);
    return service;
}


/**
 * @return <p>Request scoped bean that allows LoggableTransaction instances to be created and accessed on a request.<br/>
 * Consult <a href="http://static.springsource.org/spring/docs/3.0.x/spring-framework-reference/html/beans.html#beans-factory-scopes-other-injection">Bean Factory Scopes</a></p>
 */
@Bean
@Scope(value="request", proxyMode=ScopedProxyMode.INTERFACES)
public Token<LoggableTransaction> loggableTxToken() {
    // XXX Is this is the correct way to specify a request-scoped bean?
    LoggableTransactionToken token = new LoggableTransactionToken();
    return token;
}

这是带有@Around建议的方面的方法。

@Around("com.spp.mui.aop.Advisables.transactionLoggable()")
public Object logTransaction(ProceedingJoinPoint pjp) throws Throwable {
    // Prepare to log the execution time of the method call..
    long t0 = 0;
    t0 = System.currentTimeMillis();

    Object resultObject = null;

    try {
        resultObject = pjp.proceed();
    } catch (Throwable t) {
        logFailedTransactionAndRethrow(pjp, t0, t);
    }

    logSuccessfulTransaction(pjp, t0, resultObject);

    return resultObject;
}

Answer 1

所以，我不得不自己解决这个问题。

基础：

1）创建一个自定义ServletFilter，创建LoggableTransaction并在那里设置令牌。 我扩展了Spring的OncePerRequestFilter并使用WebApplicationContextUtils在doFilterInternal方法中获取请求范围的bean。

2）在web.xml中注册此过滤器。 另外，请确保注册Spring的RequestContextListener和ContextLoaderListener。

3）上面的方面实现，保持不变，除了切入点参考。 现在，切入点引用了一种服务方法（Web服务委托给它）。

4）这是最关键的...如果令牌未实现接口，则应使用@Scope（value =“ request”，proxyMode = ScopedProxyMode.TARGET_CLASS）装饰Bean定义。 您将在类路径上需要CGLib。 无论如何，我都需要Hibernate。

之后，事情进行得很顺利。