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Revision 10378

Added by Jing Tao over 2 years ago

Use a singleton class to get the messaging client.

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src/edu/ucsb/nceas/metacat/dataone/IndexTaskMessagingClientManager.java
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package edu.ucsb.nceas.metacat.dataone;
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import org.apache.log4j.Logger;
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import org.dataone.cn.index.messaging.IndexTaskMessagingClient;
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import org.dataone.cn.index.messaging.IndexTaskMessagingClientFactory;
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/**
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 * This class will guarantee to get a single IndexTaskMesagingClient by the singleton pattern 
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 * @author tao
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 *
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 */
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public class IndexTaskMessagingClientManager {
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    private IndexTaskMessagingClient indexTaskClient = null;
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    private static IndexTaskMessagingClientManager manager = null;
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    private static Logger logMetacat = Logger.getLogger(IndexTaskMessagingClientManager.class);
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    /**
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     * A thread safe method to get the instance of the manager
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     * @return
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     * @throws InstantiationException
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     * @throws IllegalAccessException
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     * @throws ClassNotFoundException
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     */
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    public static IndexTaskMessagingClientManager getInstance() throws InstantiationException, IllegalAccessException, ClassNotFoundException {
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        if(manager == null) {
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            synchronized (IndexTaskMessagingClientManager.class) {
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                if(manager == null) {
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                    manager = new IndexTaskMessagingClientManager();
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                }
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            }
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        }
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        return manager;
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    }
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    /**
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     * Default private constructor
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     * @throws InstantiationException
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     * @throws IllegalAccessException
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     * @throws ClassNotFoundException
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     */
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    private IndexTaskMessagingClientManager() throws InstantiationException, IllegalAccessException, ClassNotFoundException {
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        initIndexTaskClient();
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    }
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    /*
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     * Method to get the index tasks client.
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     */
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    private void initIndexTaskClient() throws InstantiationException, IllegalAccessException, ClassNotFoundException {
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        if(indexTaskClient == null) {
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            indexTaskClient = IndexTaskMessagingClientFactory.getClient();
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            logMetacat.info("IndexTaskMessagingClientManager.initIndexTaskClient - after generating the client .......................");
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        }
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    }
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    /**
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     * Get the client object which can submit the index tasks.
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     * @return
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     */
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    public IndexTaskMessagingClient getMessagingClient() {
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        return indexTaskClient;
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    }
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}

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