我编写了Java类来从IBM MQ队列中读取消息。当我使用while循环时，我能够读取队列中的第一条消息，而无法读取第二条消息
public final void ReadMessage (String queueName) throws Exception {
int options = MQC.MQOOINQUIRE + MQC.MQOOFAILIFQUIESCING + MQC.MQOOINPUTSHARED;
System.out.printin ("start Creating the Queue....... )
MQQueue myQueue = this.mqManager.accessQueue(queueName, options) ;
MQMessage mgMessage = new MQMessage ( ) ;
MQGetMessageOptions gmo = new MQGetMessageOptions ( ) ;
gmo.options = MQC.MQGMO NO WAIT + MQC.MQGMO FAIL IF QUIESCING;
gmo.matchOptions = MQC.MQMO NONE;
gmo.waitlnterval = 15000;
boolean msgqueue=true;
while(msgqueue){
try {
System.out.println("end of get Message from myqueue") ;
System.out.print In ("Message lenth" + mgMessage ( ) ) ;
mgMessage.characterSet = 300;
int length = mqMessage.getMessageLength( );
System. out ( of the message" + length) ;
System. out ( of the message" + mgMessage.readString(length)) ;
gmo.options = MQC.MQGMOWAIT | MQC.MQGMOBROWSENEXT;
if(mgMessage.getCurrentDepth()==1){
msgqueue=false;
}
}
catch (Exception e) {
msgqueue=false;
}
}
}
我想知道我还需要添加什么才能在队列中移动下一条消息。
谢谢
答案 0 :(得分：3)
我将通过在while循环内移动两行来进行尝试，因为queue.get（）调用将在返回时更新MQMessage对象实例。
MQMessage mgMessage = new MQMessage ( ) ;
MQGetMessageOptions gmo = new MQGetMessageOptions ( ) ;
由于在下一次调用中传递了相同的MQMessage对象，所以get调用将使用更新的MQMessage对象，并尝试获取message消息。
答案 1 :(得分：2)
if（mgMessage.getCurrentDepth（）== 1）
根据当前深度执行MQGet是一种不好的做法。当前的深度将在交易中包括未提交的消息！
这是一个功能齐全的Java程序，它将从队列中循环获取消息：
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.MQMessage;
import com.ibm.mq.MQGetMessageOptions;
import com.ibm.mq.MQQueue;
import com.ibm.mq.MQQueueManager;
import com.ibm.mq.constants.CMQC;
/**
* Program Name
* MQTest12L
*
* Description
* This java class will connect to a remote queue manager with the
* MQ setting stored in a HashTable, loop to retrieve all messages on a queue
* then close and disconnect.
*
* 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 MQTest12L
{
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;
private String qMgrName;
private String outputQName;
/**
* The constructor
*/
public MQTest12L()
{
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())
{
qMgrName = (String) params.get("-m");
outputQName = (String) params.get("-q");
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();
}
}
/**
* Connect, open queue, loop and get all messages then close queue and disconnect.
*
*/
private void testReceive()
{
MQQueueManager qMgr = null;
MQQueue queue = null;
int openOptions = CMQC.MQOO_INPUT_AS_Q_DEF + CMQC.MQOO_INQUIRE + CMQC.MQOO_FAIL_IF_QUIESCING;
MQGetMessageOptions gmo = new MQGetMessageOptions();
gmo.options = CMQC.MQGMO_NO_WAIT + CMQC.MQGMO_FAIL_IF_QUIESCING;
MQMessage receiveMsg = null;
int msgCount = 0;
boolean getMore = true;
try
{
qMgr = new MQQueueManager(qMgrName, mqht);
MQTest12L.logger("successfully connected to "+ qMgrName);
queue = qMgr.accessQueue(outputQName, openOptions);
MQTest12L.logger("successfully opened "+ outputQName);
while(getMore)
{
receiveMsg = new MQMessage();
try
{
// get the message on the queue
queue.get(receiveMsg, gmo);
msgCount++;
if (CMQC.MQFMT_STRING.equals(receiveMsg.format))
{
String msgStr = receiveMsg.readStringOfByteLength(receiveMsg.getMessageLength());
// MQTest12L.logger("["+msgCount+"] " + msgStr);
}
else
{
byte[] b = new byte[receiveMsg.getMessageLength()];
receiveMsg.readFully(b);
// MQTest12L.logger("["+msgCount+"] " + new String(b));
}
}
catch (MQException e)
{
if ( (e.completionCode == CMQC.MQCC_FAILED) &&
(e.reasonCode == CMQC.MQRC_NO_MSG_AVAILABLE) )
{
// All messages read.
getMore = false;
break;
}
else
{
MQTest12L.logger("MQException: " + e.getLocalizedMessage());
MQTest12L.logger("CC=" + e.completionCode + " : RC=" + e.reasonCode);
getMore = false;
break;
}
}
catch (IOException e)
{
MQTest12L.logger("IOException:" +e.getLocalizedMessage());
}
}
}
catch (MQException e)
{
MQTest12L.logger("CC=" +e.completionCode + " : RC=" + e.reasonCode);
}
finally
{
MQTest12L.logger("read " + msgCount + " messages");
try
{
if (queue != null)
{
queue.close();
MQTest12L.logger("closed: "+ outputQName);
}
}
catch (MQException e)
{
MQTest12L.logger("CC=" +e.completionCode + " : RC=" + e.reasonCode);
}
try
{
if (qMgr != null)
{
qMgr.disconnect();
MQTest12L.logger("disconnected from "+ qMgrName);
}
}
catch (MQException e)
{
MQTest12L.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);
}
/**
* main line
* @param args
*/
public static void main(String[] args)
{
MQTest12L write = new MQTest12L();
try
{
write.init(args);
write.testReceive();
}
catch (IllegalArgumentException e)
{
System.err.println("Usage: java MQTest12L -m QueueManagerName -h host -p port -c channel -q QueueName -u UserID -x Password");
System.exit(1);
}
System.exit(0);
}
}
答案 2 :(得分：1)
如果您没有在循环中移动MQMessage构造函数（如@Shashi建议的那样），则必须在循环中执行以下操作：
mgMessage.clearMessage();
mgMessage.correlationId = MQC.MQCI_NONE;
mgMessage.messageId = MQC.MQMI_NONE;