使用来自 IBM MQ 的所有消息

Question

我想消费来自 MQ 的所有消息。

public static void main(String[] args)
{ 
 JMSContext context = null;
 Destination destination = null;
 JMSConsumer consumer = null;

 JmsFactoryFactory FF = JmsFactoryFactory.getInstance(WMQConstants.WMQ_PROVIDER);
 JmsConnectionFactor CF = FF.createConnectionFactory();
  context = CF.createContext();
  destination = context.createQueue(QUEUE_NAME);
  consumer = context.createConsumer(destination);
  String msg = consumer.receiveBody(String.class, 15090);
  System.out.println(msg);
 }

它只能阅读一条消息。如何使用所有消息？另外，有没有更简单的方法可以删除队列中的所有消息，甚至不读取或使用它们？

Answer 1

有没有更简单的方法来删除队列中的所有消息，甚至不 阅读或消费它们？

是的。您可以使用 MQ PCF Clear Queue 命令，只要没有应用程序为输入或输出打开队列。即 IPPROCS 和 OPPROCS 必须为零才能正常工作。这也适用于 Morag 的 MQSC Clear 命令。

这是一个用于清除队列的功能齐全的 Java MQ PCF 程序。

import java.io.IOException;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Hashtable;

import com.ibm.mq.MQException;
import com.ibm.mq.MQQueueManager;
import com.ibm.mq.constants.CMQC;
import com.ibm.mq.constants.CMQCFC;
import com.ibm.mq.headers.MQDataException;
import com.ibm.mq.headers.pcf.PCFMessage;
import com.ibm.mq.headers.pcf.PCFMessageAgent;

/**
 * Program Name
 *  MQClearQueue01
 *
 * Description
 *  This java class issues a PCF "Clear Q" command for a queue to delete all messages 
 *  in the queue of a remote queue manager.
 *
 * Sample Command Line Parameters
 *  -m MQA1 -h 127.0.0.1 -p 1414 -c TEST.CHL -q TEST.Q1 -u UserID -x Password
 *
 * @author Roger Lacroix
 */
public class MQClearQueue01
{
   private static final SimpleDateFormat  LOGGER_TIMESTAMP = new SimpleDateFormat("yyyy/MM/dd HH:mm:ss.SSS");

   private Hashtable<String,String> params;
   private Hashtable<String,Object> mqht;

   public MQClearQueue01()
   {
      super();
      params = new Hashtable<String,String>();
      mqht = new Hashtable<String,Object>();
   }

   /**
    * Make sure the required parameters are present.
    * @return true/false
    */
   private boolean allParamsPresent()
   {
      boolean b = params.containsKey("-h") && params.containsKey("-p") &&
                  params.containsKey("-c") && params.containsKey("-m") &&
                  params.containsKey("-q") &&
                  params.containsKey("-u") && params.containsKey("-x");
      if (b)
      {
         try
         {
            Integer.parseInt((String) params.get("-p"));
         }
         catch (NumberFormatException e)
         {
            b = false;
         }
      }

      return b;
   }

   /**
    * Extract the command-line parameters and initialize the MQ HashTable.
    * @param args
    * @throws IllegalArgumentException
    */
   private void init(String[] args) throws IllegalArgumentException
   {
      int port = 1414;
      if (args.length > 0 && (args.length % 2) == 0)
      {
         for (int i = 0; i < args.length; i += 2)
         {
            params.put(args[i], args[i + 1]);
         }
      }
      else
      {
         throw new IllegalArgumentException();
      }

      if (allParamsPresent())
      {
         try
         {
            port = Integer.parseInt((String) params.get("-p"));
         }
         catch (NumberFormatException e)
         {
            port = 1414;
         }

         mqht.put(CMQC.CHANNEL_PROPERTY, params.get("-c"));
         mqht.put(CMQC.HOST_NAME_PROPERTY, params.get("-h"));
         mqht.put(CMQC.PORT_PROPERTY, new Integer(port));
         mqht.put(CMQC.USER_ID_PROPERTY, params.get("-u"));
         mqht.put(CMQC.PASSWORD_PROPERTY, params.get("-x"));

         // I don't want to see MQ exceptions at the console.
         MQException.log = null;
      }
      else
      {
         throw new IllegalArgumentException();
      }
   }

   /**
    * Handle connecting to the queue manager, issuing PCF command then
    * looping through PCF response messages and disconnecting from
    * the queue manager.
    */
   private void doPCF()
   {
      MQQueueManager  qMgr   = null;
      PCFMessageAgent agent  = null;
      PCFMessage   request   = null;
      PCFMessage[] responses = null;
      String qMgrName  = (String) params.get("-m");
      String queueName = (String) params.get("-q");

      try
      {
         qMgr = new MQQueueManager(qMgrName, mqht);
         MQClearQueue01.logger("successfully connected to "+ qMgrName);

         agent = new PCFMessageAgent(qMgr);
         MQClearQueue01.logger("successfully created agent");

         // https://www.ibm.com/support/knowledgecenter/SSFKSJ_latest/com.ibm.mq.ref.adm.doc/q087420_.html
         request = new PCFMessage(CMQCFC.MQCMD_CLEAR_Q);

         request.addParameter(CMQC.MQCA_Q_NAME, queueName);

         responses = agent.send(request);

         MQClearQueue01.logger("responses.length="+responses.length);

         for (int i = 0; i < responses.length; i++)
         {
            if ((responses[i]).getCompCode() == CMQC.MQCC_OK)
               MQClearQueue01.logger("Successfully cleared queue '"+queueName+"' of messages.");
            else
               MQClearQueue01.logger("Error: Failed to clear queue '"+queueName+"' of messages.");
         }
      }
      catch (MQException e)
      {
         MQClearQueue01.logger("CC=" +e.completionCode + " : RC=" + e.reasonCode);
      }
      catch (IOException e)
      {
         MQClearQueue01.logger("IOException:" +e.getLocalizedMessage());
      }
      catch (MQDataException e)
      {
         MQClearQueue01.logger("MQDataException:" +e.getLocalizedMessage());
      }
      finally
      {
         try
         {
            if (agent != null)
            {
               agent.disconnect();
               MQClearQueue01.logger("disconnected from agent");
            }
         }
         catch (MQDataException e)
         {
            MQClearQueue01.logger("CC=" +e.completionCode + " : RC=" + e.reasonCode);
         }

         try
         {
            if (qMgr != null)
            {
               qMgr.disconnect();
               MQClearQueue01.logger("disconnected from "+ qMgrName);
            }
         }
         catch (MQException e)
         {
            MQClearQueue01.logger("CC=" +e.completionCode + " : RC=" + e.reasonCode);
         }
      }
   }

   /**
    * A simple logger method
    * @param data
    */
   public static void logger(String data)
   {
      String className = Thread.currentThread().getStackTrace()[2].getClassName();

      // Remove the package info.
      if ( (className != null) && (className.lastIndexOf('.') != -1) )
         className = className.substring(className.lastIndexOf('.')+1);

      System.out.println(LOGGER_TIMESTAMP.format(new Date())+" "+className+": "+Thread.currentThread().getStackTrace()[2].getMethodName()+": "+data);
   }

   public static void main(String[] args)
   {
      MQClearQueue01 mqcq = new MQClearQueue01();

      try
      {
         mqcq.init(args);
         mqcq.doPCF();
      }
      catch (IllegalArgumentException e)
      {
         MQClearQueue01.logger("Usage: java MQClearQueue01 -m QueueManagerName -h host -p port -c channel -q QueueName -u UserID -x Password");
         System.exit(1);
      }

      System.exit(0);
   }
}

Answer 2

如果正如您的问题所暗示的那样，您只想清空队列中的所有消息，而不是在应用程序中实际读取它们，您可以考虑简单地使用管理 MQSC 命令：-

CLEAR QLOCAL(queue-name)

您可以将其键入runmqsc 工具以将其发送给队列管理器。

Answer 3

JMS API 一次使用一条消息，因此您需要将 receiveBody 放入一个循环中，例如：

public static void main(String[] args) { 
   JMSContext context = null;
   Destination destination = null;
   JMSConsumer consumer = null;

   JmsFactoryFactory FF = JmsFactoryFactory.getInstance(WMQConstants.WMQ_PROVIDER);
   JmsConnectionFactor CF = FF.createConnectionFactory();
   context = CF.createContext();
   destination = context.createQueue(QUEUE_NAME);
   consumer = context.createConsumer(destination);
   String msg = null;
   do {
      msg = consumer.receiveBody(String.class, 15090);
      System.out.println(msg);
   } while (msg != null);
}

当receiveBody 返回null 时，表示队列中没有更多消息。

JMS API 没有定义从队列中删除所有消息的任何方法，但大多数 JMS 服务器都有一个特定于实现的管理 API，您可以通过它执行这些操作。