使用 RabbitTemplate 在接收回复消息时获取 NPE

Question

我有两个微服务。一个包含具有 Get 方法的 REST 控制器，该方法在发送到特定队列时接收消息。其他微服务只是将回复消息发送到同一个队列，以便在访问 REST API 时可以在浏览器中看到已处理的消息

但是，在接收消息时获取 NPE。 以下是完整的堆栈跟踪：

2018-05-19 15:46:13.409  INFO 30104 --- [nio-8097-exec-1] o.a.c.c.C.[Tomcat].[localhost].[/unit]   : Initializing Spring FrameworkServlet 'dispatcherServlet' 2018-05-19 15:46:13.409  INFO 30104 --- [nio-8097-exec-1] o.s.web.servlet.DispatcherServlet        : FrameworkServlet 'dispatcherServlet': initialization started 2018-05-19 15:46:13.443  INFO 30104 --- [nio-8097-exec-1] o.s.web.servlet.DispatcherServlet        : FrameworkServlet 'dispatcherServlet': initialization completed in 34 ms 2018-05-19 15:46:13.533  INFO 30104 --- [nio-8097-exec-1] o.s.a.r.c.CachingConnectionFactory       : Attempting to connect to: [35.154.27.134:5672] 2018-05-19 15:46:13.593  INFO 30104 --- [nio-8097-exec-1] o.s.a.r.c.CachingConnectionFactory       : Created new connection: rabbitConnectionFactory#5b2b49d6:0/SimpleConnection@3e4f13fa [delegate=amqp://guest@35.154.27.134:5672/, localPort= 58742] 2018-05-19 15:46:18.681 ERROR 30104 --- [nio-8097-exec-1] o.a.c.c.C.[.[.[.[dispatcherServlet]      : Servlet.service() for servlet [dispatcherServlet] in context with path [/unit] threw exception [Request processing failed; nested exception is java.lang.NullPointerException] with root cause

java.lang.NullPointerException: null
        at com.infy.ci.unitamqpservice.UnitAmqpRestController.getAggregatedDataForSectionOfNightlyBuild(UnitAmqpRestController.java:83) ~[classes!/:0.0.1-SNAPSHOT]
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_151]
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_151]
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_151]
        at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_151]
        at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:205) ~[spring-web-4.3.14.RELEASE.jar!/:4.3.14.RELEASE]
        at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:133) ~[spring-web-4.3.14.RELEASE.jar!/:4.3.14.RELEASE]
        at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:97) ~[spring-webmvc-4.3.14.RELEASE.jar!/:4.3.14.RELEASE]
        at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:827) ~[spring-webmvc-4.3.14.RELEASE.jar!/:4.3.14.RELEASE]
        at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:738) ~[spring-webmvc-4.3.14.RELEASE.jar!/:4.3.14.RELEASE]
        at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:85) ~[spring-webmvc-4.3.14.RELEASE.jar!/:4.3.14.RELEASE]
        at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:967) ~[spring-webmvc-4.3.14.RELEASE.jar!/:4.3.14.RELEASE]
        at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:901) ~[spring-webmvc-4.3.14.RELEASE.jar!/:4.3.14.RELEASE]
        at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:970) ~[spring-webmvc-4.3.14.RELEASE.jar!/:4.3.14.RELEASE]
        at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:861) ~[spring-webmvc-4.3.14.RELEASE.jar!/:4.3.14.RELEASE]
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:635) ~[tomcat-embed-core-8.5.27.jar!/:8.5.27]
        at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:846) ~[spring-webmvc-4.3.14.RELEASE.jar!/:4.3.14.RELEASE]
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:742) ~[tomcat-embed-core-8.5.27.jar!/:8.5.27]
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231) ~[tomcat-embed-core-8.5.27.jar!/:8.5.27]
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-8.5.27.jar!/:8.5.27]
        at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52) ~[tomcat-embed-websocket-8.5.27.jar!/:8.5.27]
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-8.5.27.jar!/:8.5.27]
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-8.5.27.jar!/:8.5.27]
        at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:99) ~[spring-web-4.3.14.RELEASE.jar!/:4.3.14.RELEASE]
        at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.3.14.RELEASE.jar!/:4.3.14.RELEASE]
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-8.5.27.jar!/:8.5.27]
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-8.5.27.jar!/:8.5.27]
        at org.springframework.web.filter.HttpPutFormContentFilter.doFilterInternal(HttpPutFormContentFilter.java:108) ~[spring-web-4.3.14.RELEASE.jar!/:4.3.14.RELEASE]
        at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.3.14.RELEASE.jar!/:4.3.14.RELEASE]
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-8.5.27.jar!/:8.5.27]
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-8.5.27.jar!/:8.5.27]
        at org.springframework.web.filter.HiddenHttpMethodFilter.doFilterInternal(HiddenHttpMethodFilter.java:81) ~[spring-web-4.3.14.RELEASE.jar!/:4.3.14.RELEASE]
        at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.3.14.RELEASE.jar!/:4.3.14.RELEASE]
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-8.5.27.jar!/:8.5.27]
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-8.5.27.jar!/:8.5.27]
        at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:197) ~[spring-web-4.3.14.RELEASE.jar!/:4.3.14.RELEASE]
        at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.3.14.RELEASE.jar!/:4.3.14.RELEASE]
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-8.5.27.jar!/:8.5.27]
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-8.5.27.jar!/:8.5.27]
        at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:199) ~[tomcat-embed-core-8.5.27.jar!/:8.5.27]
        at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96) [tomcat-embed-core-8.5.27.jar!/:8.5.27]
        at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:504) [tomcat-embed-core-8.5.27.jar!/:8.5.27]
        at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:140) [tomcat-embed-core-8.5.27.jar!/:8.5.27]
        at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:81) [tomcat-embed-core-8.5.27.jar!/:8.5.27]
        at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:87) [tomcat-embed-core-8.5.27.jar!/:8.5.27]
        at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:342) [tomcat-embed-core-8.5.27.jar!/:8.5.27]
        at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:803) [tomcat-embed-core-8.5.27.jar!/:8.5.27]
        at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66) [tomcat-embed-core-8.5.27.jar!/:8.5.27]
        at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:790) [tomcat-embed-core-8.5.27.jar!/:8.5.27]
        at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1459) [tomcat-embed-core-8.5.27.jar!/:8.5.27]
        at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) [tomcat-embed-core-8.5.27.jar!/:8.5.27]
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) [na:1.8.0_151]
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) [na:1.8.0_151]
        at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) [tomcat-embed-core-8.5.27.jar!/:8.5.27]
        at java.lang.Thread.run(Thread.java:748) [na:1.8.0_151]

此外，当在 Web 浏览器中点击 REST API 时，控制台上会出现以下日志

2018-05-19 15:45:22.328 信息 30023 --- [主要] o.s.j.e.a.AnnotationMBeanExporter : 定位托管 bean 'rabbitConnectionFactory'：向 JMX 服务器注册为 MBean [org.springframework.amqp.rabbit.connection:name=rabbitConnectionFactory,type=CachingConnectionFactory] 2018-05-19 15:45:22.423 信息 30023 --- [主要] o.s.c.support.DefaultLifecycleProcessor ：分阶段启动 bean 2147483647 2018-05-19 15:45:22.445 信息 30023 --- [cTaskExecutor-1] o.s.a.r.c.CachingConnectionFactory ：尝试连接到： [35.154.27.134:5672] 2018-05-19 15:45:22.471 信息 30023 --- [cTaskExecutor-1] o.s.a.r.c.CachingConnectionFactory：已创建 新连接： rabbitConnectionFactory#325fc787:0/SimpleConnection@38a7acf7 [代表=amqp://guest@35.154.27.134:5672/，localPort=58736] 2018-05-19 15:45:22.875 信息 30023 --- [主要] s.b.c.e.t.TomcatEmbeddedServletContainer ：Tomcat 在端口上启动： 8099 (http) 2018-05-19 15:45:22.902 信息 30023 --- [主要] com.infy.ci.unitdbamqpservice.RPCServer ：在 7.517 中启动 RPCServer 秒（JVM 运行 8.286） 2018 年 5 月 19 日星期六 15:45:23 UTC 警告： 不经过服务器身份验证建立 SSL 连接是 不建议。根据 MySQL 5.5.45+、5.6.26+ 和 5.7.6+ 要求如果显式，则必须默认建立 SSL 连接 选项未设置。为了符合现有的应用程序不使用 SSL 的 verifyServerCertificate 属性设置为 'false'。你需要 通过设置 useSSL=false 显式禁用 SSL，或设置 useSSL=true 并为服务器证书提供信任库 确认。 2018 年 5 月 19 日星期六 15:46:13 UTC 警告：建立 SSL 不推荐没有服务器身份验证的连接。 根据 MySQL 5.5.45+、5.6.26+ 和 5.7.6+ 要求 SSL 如果没有显式选项，则必须默认建立连接 放。为了符合不使用 SSL 的现有应用程序， verifyServerCertificate 属性设置为“假”。你需要要么 通过设置 useSSL=false 或设置 useSSL=true 显式禁用 SSL 和 为服务器证书验证提供信任库。

这可能是 NPE 的原因吗？我已经在 J​​DBC 代码中包含了以下内容，但仍然没有运气。

prop.setProperty("useSSL", "false");
prop.setProperty("autoReconnect", "true");

这两个服务都在 github 上签入：

• https://github.com/irfanjs/unitamqpservice

• https://github.com/irfanjs/unitdbamqpservice

Answer 1

return rabbitTemplate.convertSendAndReceive("myExchange", requestQueueName, message).toString();

您在回复时无条件致电toString()。

如果在收到回复之前超过了模板的replyTimeout，则回复将是null（超时默认为5秒）。

您必须在调用toString() 之前检查null 结果。

只是将回复消息发送到同一个队列

您不能将回复发送到同一个队列 - 它必须发送到请求中的 replyTo 标头。

如果您在服务器端使用@RabbitListener 或MessageListenerAdapter，它将为您处理。

这与 SSL 无关

警告：不建议在没有服务器身份验证的情况下建立 SSL 连接。根据 MySQL 5.5.45+、5.6.26+ 和 5.7.6+ 的要求，如果未设置显式选项，则默认情况下必须建立 SSL 连接。

那个警告是关于 MySQL 的。

编辑

我刚刚将你的应用程序破解到最低限度，它们对我来说工作得很好......

@Controller
@Configuration
@PropertySource("classpath:/application.properties")
@RequestMapping("/unittestdata")
public class UnitAmqpRestController {

    private final String requestQueueName = "rpc_queue1";

    @Bean
    public static PropertySourcesPlaceholderConfigurer propertySourcesPlaceholderConfigurer() {
        return new PropertySourcesPlaceholderConfigurer();
    }

    private final Logger logger = LoggerFactory.getLogger(UnitAmqpRestController.class);

    private final RabbitTemplate rabbitTemplate;

    @Autowired
    public UnitAmqpRestController(RabbitTemplate rabbitTemplate) {
        this.rabbitTemplate = rabbitTemplate;
        rabbitTemplate.setReplyTimeout(15_000L);
    }

    @RequestMapping(value = "/{projectid}/ut/aggregate",
            method = RequestMethod.GET,
            produces = MediaType.TEXT_HTML_VALUE)
    public @ResponseBody String getAggregatedDataForSectionOfNightlyBuild(@PathVariable("projectid") int projectid,
            @RequestParam("buildtype") String buildtype, @RequestParam("build") String build) throws Exception {

        if (build.toLowerCase().equals("latest") && buildtype.equals("nightly")) {

            String message = String.format("aggregate");
            logger.info("Sending: " + message);
            Object returned = rabbitTemplate.convertSendAndReceive("", requestQueueName, message);
            logger.info("Reply: " + returned);
            if (returned == null) {
                throw new RuntimeException("failed to get a response");
            }
            return returned.toString();

        }
        else {
            return null;
        }

    }

}

和

@Configuration
@SpringBootApplication
@PropertySource("classpath:/application.properties")
public class RPCServer {

    private static final Logger logger = LoggerFactory.getLogger(RPCServer.class);

    public static void main(String[] args) throws IOException, TimeoutException, InterruptedException {
        SpringApplication.run(RPCServer.class, args);
    }

    private static final String RPC_QUEUE_NAME = "rpc_queue1";

    @Bean
    public Queue queue() {
        return new Queue(RPC_QUEUE_NAME);
    }

    @Component
    public static class RpcListener {

        @RabbitListener(queues = RPC_QUEUE_NAME)
        public String reply(String request) throws IOException, TimeoutException, ClassNotFoundException, SQLException {
            logger.info(request);
            return request.toUpperCase();
        }

    }

}

和

2018-05-20 12:46:00.298  INFO 13369 --- [nio-8097-exec-1] c.i.c.u.UnitAmqpRestController           : Sending: aggregate
...
o.s.amqp.rabbit.core.RabbitTemplate      : Publishing message on exchange [], routingKey = [rpc_queue1]
2018-05-20 12:46:00.554 DEBUG 13369 --- [nio-8097-exec-1] o.s.amqp.rabbit.core.RabbitTemplate      : Reply: (Body:'AGGREGATE' MessageProperties [headers={}, timestamp=null, messageId=null, userId=null, receivedUserId=null, appId=null, clusterId=null, type=null, correlationId=null, correlationIdString=null, replyTo=null, contentType=text/plain, contentEncoding=UTF-8, contentLength=0, deliveryMode=null, receivedDeliveryMode=PERSISTENT, expiration=null, priority=0, redelivered=false, receivedExchange=, receivedRoutingKey=amq.rabbitmq.reply-to.g2dkABByYWJiaXRAbG9jYWxob3N0AAAHFAAAAAAC.3M1LyvOdR9dHQehSV4l67A==, receivedDelay=null, deliveryTag=1, messageCount=null, consumerTag=null, consumerQueue=null])
2018-05-20 12:46:00.561  INFO 13369 --- [nio-8097-exec-1] c.i.c.u.UnitAmqpRestController           : Reply: AGGREGATE