无法从 JMS ActiveMQ 队列中删除消息

Question

我是jms技术的新手。我正在使用activeMQ控制台来监视队列。我可以创建包含消息的队列。但是当我尝试删除某些队列时..一个例外即将到来。尝试了很多事情，但都是静脉..下面是我的代码：

法典

BrokerService brokerService = new BrokerService();
try {
brokerService.start(true);
brokerService.start();
brokerService.autoStart();
brokerService.setUseJmx(true);
brokerService.addConnector("tcp://localhost:61616");
Thread.sleep(10000);
System.out.println("brokerService : "+brokerService.isStarted());
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}

BrokerFacadeSupport facade=   new LocalBrokerFacade(brokerService);
try {
QueueViewMBean queue = facade.getQueue(queue_name);
if(queue==null) {
System.out.println("!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!");
}
int count = this.jmsTemplate.browse(queue_name, new BrowserCallback<Integer>() {
public Integer doInJms(final Session session, final QueueBrowser browser) throws JMSException {
Queue queue1 = browser.getQueue();
Enumeration enumeration = browser.getEnumeration();
int counter = 0;
while (enumeration.hasMoreElements()) {
Message msg = (Message) enumeration.nextElement();
msg.acknowledge();
ActiveMQTextMessage atm  = (ActiveMQTextMessage) msg;
atm.setDroppable(true);
atm.setReadOnlyProperties(false);
atm.setReadOnlyBody(false);
atm.acknowledge();
msg.setBooleanProperty("readOnlyProperties", false);
msg.setBooleanProperty("readOnlyBody", false);
msg.setBooleanProperty("droppable", true);
Enumeration enum_ = atm.getPropertyNames();
while(enum_.hasMoreElements()) {
String name  = (String) enum_.nextElement();
System.out.println("## : "+name);
}
try {
System.out.println("--"+atm.getJMSMessageID());
System.out.println();
queue.removeMessage(atm.getJMSMessageID());
}catch(Exception ex) {
ex.printStackTrace();
}
System.out.println(String.format("tFound : %s", msg));
counter += 1;
}
return counter;
}
});
queue.purge();
}catch(Exception ex) {
ex.printStackTrace();
}

输出

输出到System.out.println(String.format("tFound : %s", msg));是：

Found : ActiveMQTextMessage {commandId = 5, responseRequired = true, messageId = ID:CRM-PC-50101-1528866712471-1:1:1:1:1, originalDestination = null, originalTransactionId = null, producerId = ID:CRM-PC-50101-1528866712471-1:1:1:1, destination = queue://testNexus, transactionId = null, expiration = 0, timestamp = 1528866713408, arrival = 0, brokerInTime = 1528866713410, brokerOutTime = 1529047482640, correlationId = null, replyTo = null, persistent = true, type = null, priority = 4, groupID = null, groupSequence = 0, targetConsumerId = null, compressed = false, userID = null, content = org.apache.activemq.util.ByteSequence@12b82970, marshalledProperties = org.apache.activemq.util.ByteSequence@49abe550, dataStructure = null, redeliveryCounter = 0, size = 0, properties = {_type=com.crm.jms.SampleObject}, readOnlyProperties = true, readOnlyBody = true, droppable = false, jmsXGroupFirstForConsumer = false, text = {"msg":"hello world"}}

最终输出控制台

==>   _type : com.crm.jms.SampleObject
--ID:Crm-PC-50101-1528866712471-1:1:1:1:1
java.lang.NullPointerException
at com.crm.jms.controller.QueueController$1.doInJms(QueueController.java:171)
at com.crm.jms.controller.QueueController$1.doInJms(QueueController.java:1)
at org.springframework.jms.core.JmsTemplate$14.doInJms(JmsTemplate.java:1033)
at org.springframework.jms.core.JmsTemplate.execute(JmsTemplate.java:484)
at org.springframework.jms.core.JmsTemplate.browseSelected(JmsTemplate.java:1027)
at org.springframework.jms.core.JmsTemplate.browse(JmsTemplate.java:989)
at com.crm.jms.controller.QueueController.deleteQueue(QueueController.java:153)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
.
.
.
.
Found : ActiveMQTextMessage {commandId = 5, responseRequired = true, messageId = ID:Crm-PC-50101-1528866712471-1:1:1:1:1, originalDestination = null, originalTransactionId = null, producerId = ID:Crm-PC-50101-1528866712471-1:1:1:1, destination = queue://testNexus, transactionId = null, expiration = 0, timestamp = 1528866713408, arrival = 0, brokerInTime = 1528866713410, brokerOutTime = 1529049245130, correlationId = null, replyTo = null, persistent = true, type = null, priority = 4, groupID = null, groupSequence = 0, targetConsumerId = null, compressed = false, userID = null, content = org.apache.activemq.util.ByteSequence@5b55f70f, marshalledProperties = org.apache.activemq.util.ByteSequence@3e116ae6, dataStructure = null, redeliveryCounter = 0, size = 0, properties = {_type=com.crm.jms.SampleObject}, readOnlyProperties = true, readOnlyBody = true, droppable = false, jmsXGroupFirstForConsumer = false, text = {"msg":"hello world"}}
java.lang.NullPointerException
at com.crm.jms.controller.QueueController.deleteQueue(QueueController.java:181)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:205)
at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:133)
at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:97)
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:827)
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:738)
at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:85)
.
.
.
.

Answer 1

为什么您确认您正在浏览(而不是消费(的消息？

Enumeration enumeration = browser.getEnumeration();
...
Message msg = (Message) enumeration.nextElement();
msg.acknowledge();

正如你所注意到的，javax.jms.Queue 上确实没有 delete((/remove(( 方法，但你可以通过只使用所需的消息(仍然使用纯 JMS API(来达到相同的结果：

MessageConsumer consumer = session.createConsumer(myQueue, "JMSMessageID = '" + messageId + "'");
Message message = consumer.receive(TIMEOUT);
message.acknowledge();

Answer 2

问题是您没有启动BrokerService因此facade.getQueue(queueName)方法将返回null。为什么？因为外观对象不知道您要求哪个活动的 mq 服务器。

当然，您正在获得有关消息的一些信息，因为您正在与正在运行的代理服务器的jmsTemplate连接。

queue.purge();和queue.removeMessage(msg.getJMSMessageID());上会引发异常，因为queuenull。

我建议删除BrokerService和BrokerServiceFacade的东西，并通过browser.getQueue()方法从QueueBrowser参数中获取回调中的Queue对象。