我的spring-boot应用程序抛出一个连接超时错误，它永远无法连接。以下是我用来尝试连接到rabbitmq:的代码
CachingConnectionFactory connectionFactory =
new CachingConnectionFactory("localhost");
connectionFactory.setUsername("guest");
connectionFactory.setPassword("guest");
connectionFactory.setPort(9000);
AmqpAdmin admin = new RabbitAdmin(connectionFactory);
admin.declareQueue(new Queue("myqueue"));
AmqpTemplate template = new RabbitTemplate(connectionFactory);
template.convertAndSend("myqueue", "foo");
String foo = (String) template.receiveAndConvert("myqueue");
p.S：我机器上的rabbitmq正在localhost上运行，端口9000
当我运行上面的代码时，我得到以下错误：
java.util.concurrent.TimeoutException: null
at com.rabbitmq.utility.BlockingCell.get(BlockingCell.java:77) ~[amqp-client-4.0.2.jar:4.0.2]
at com.rabbitmq.utility.BlockingCell.uninterruptibleGet(BlockingCell.java:120) ~[amqp-client-4.0.2.jar:4.0.2]
at com.rabbitmq.utility.BlockingValueOrException.uninterruptibleGetValue(BlockingValueOrException.java:36) ~[amqp-client-4.0.2.jar:4.0.2]
at com.rabbitmq.client.impl.AMQChannel$BlockingRpcContinuation.getReply(AMQChannel.java:372) ~[amqp-client-4.0.2.jar:4.0.2]
at com.rabbitmq.client.impl.AMQConnection.start(AMQConnection.java:297) ~[amqp-client-4.0.2.jar:4.0.2]
at com.rabbitmq.client.ConnectionFactory.newConnection(ConnectionFactory.java:909) ~[amqp-client-4.0.2.jar:4.0.2]
at com.rabbitmq.client.ConnectionFactory.newConnection(ConnectionFactory.java:859) ~[amqp-client-4.0.2.jar:4.0.2]
at com.rabbitmq.client.ConnectionFactory.newConnection(ConnectionFactory.java:1000) ~[amqp-client-4.0.2.jar:4.0.2]
at org.springframework.amqp.rabbit.connection.AbstractConnectionFactory.createBareConnection(AbstractConnectionFactory.java:355) ~[spring-rabbit-1.7.2.RELEASE.jar:na]
at org.springframework.amqp.rabbit.connection.CachingConnectionFactory.createConnection(CachingConnectionFactory.java:565) ~[spring-rabbit-1.7.2.RELEASE.jar:na]
at org.springframework.amqp.rabbit.core.RabbitTemplate.doExecute(RabbitTemplate.java:1430) ~[spring-rabbit-1.7.2.RELEASE.jar:na]
at org.springframework.amqp.rabbit.core.RabbitTemplate.execute(RabbitTemplate.java:1411) ~[spring-rabbit-1.7.2.RELEASE.jar:na]
at org.springframework.amqp.rabbit.core.RabbitTemplate.execute(RabbitTemplate.java:1387) ~[spring-rabbit-1.7.2.RELEASE.jar:na]
at org.springframework.amqp.rabbit.core.RabbitAdmin.declareQueue(RabbitAdmin.java:207) ~[spring-rabbit-1.7.2.RELEASE.jar:na]
at com.javainuse.service.RabbitMQSender.send(RabbitMQSender.java:39) ~[classes/:na]
at com.javainuse.controller.RabbitMQWebController.producer(RabbitMQWebController.java:25) ~[classes/:na]
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_181]
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_181]
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_181]
at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_181]
at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:205) ~[spring-web-4.3.8.RELEASE.jar:4.3.8.RELEASE]
at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:133) ~[spring-web-4.3.8.RELEASE.jar:4.3.8.RELEASE]
at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:97) ~[spring-webmvc-4.3.8.RELEASE.jar:4.3.8.RELEASE]
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:827) ~[spring-webmvc-4.3.8.RELEASE.jar:4.3.8.RELEASE]
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:738) ~[spring-webmvc-4.3.8.RELEASE.jar:4.3.8.RELEASE]
at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:85) ~[spring-webmvc-4.3.8.RELEASE.jar:4.3.8.RELEASE]
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:963) ~[spring-webmvc-4.3.8.RELEASE.jar:4.3.8.RELEASE]
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:897) ~[spring-webmvc-4.3.8.RELEASE.jar:4.3.8.RELEASE]
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:970) ~[spring-webmvc-4.3.8.RELEASE.jar:4.3.8.RELEASE]
at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:861) ~[spring-webmvc-4.3.8.RELEASE.jar:4.3.8.RELEASE]
at javax.servlet.http.HttpServlet.service(HttpServlet.java:635) ~[tomcat-embed-core-8.5.14.jar:8.5.14]
at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:846) ~[spring-webmvc-4.3.8.RELEASE.jar:4.3.8.RELEASE]
at javax.servlet.http.HttpServlet.service(HttpServlet.java:742) ~[tomcat-embed-core-8.5.14.jar:8.5.14]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231) ~[tomcat-embed-core-8.5.14.jar:8.5.14]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-8.5.14.jar:8.5.14]
是否更新了RabbitMQ Java客户端？也许RabbitMQ服务器上的磁盘空间已满，所以它停止接受连接。
在application.properties:中添加
spring.rabbitmq.connection-timeout=10000
spring.rabbitmq.host=localhost
spring.rabbitmq.port=9000
spring.rabbitmq.username=guest
spring.rabbitmq.password=guest