实时索引管理类IndexManager-Lucene案例开发

转载请注明出处：http://blog.csdn.net/xiaojimanman/article/details/44015983

http://www.llwjy.com/blogdetail/5757ce8c007754704b563dd6a47ca1ca.html

个人的博客小站也搭建成功，网址：www.llwjy.com ，欢迎大家来吐槽~

在前一篇博客中，对实时索引的实现原理做了一些简单的介绍，这里就介绍下，如何利用Lucene来实现索引的管理（Lucene中已经实现了大部分的功能，我们只需要对其再次封装即可）。

逐个击破

在Lucene4.3.1中，实现实时索引时，需要将IndexWrite的相关操作委托给TrackingIndexWriter来处理，具体代码实现如下：

ps:关于如何创建索引这里就不再介绍了，可以参照之前的博客或者该博客后面的完整代码。

this.trackingIndexWriter = new TrackingIndexWriter(this.indexWriter);

同时初始化索引管理对象，代码如下：

this.nrtManager = new NRTManager(this.trackingIndexWriter, new SearcherFactory());

到这里还需要开启两个守护线程：内存索引重读线程和内存数据commit线程。内存索引重读线程执行的频率也就是实时索引的时差，由于内存中的数据不会太多，所以这个延时一般也就是在十几毫秒左右；内存数据commit线程是将内存中的数据写到磁盘上，不至于数据丢失，如果研究过Lucene源码的童鞋也许会发现，即使你不执行commit操作，到内存中的数据达到一定的程度，也会将一部分数据写到磁盘上，只不过重启服务这部分数据就丢失了同时还会造成一系列的问题，http://bbs.csdn.net/topics/390677902 这个地址下就是commit线程死掉之后造成的一系列问题，感兴趣的童鞋可以了解下。

内存重读线程我们只需要配置下参数启动即可，代码如下：

this.nrtManagerReopenThread = new NRTManagerReopenThread(this.nrtManager, indexReopenMaxStaleSec, indexReopenMinStaleSec);
this.nrtManagerReopenThread.setName("NRTManager Reopen Thread");
this.nrtManagerReopenThread.setPriority(Math.min(Thread.currentThread().getPriority()+2, Thread.MAX_PRIORITY));
this.nrtManagerReopenThread.setDaemon(true);
this.nrtManagerReopenThread.start();

内存数据commit线程需要自己写代码实现，然后启动该线程即可，代码如下：

private class IndexCommitThread extends Thread{
	private boolean flag;
	public IndexCommitThread(String name){
		super(name);
	}
	
	@SuppressWarnings("deprecation")
	public void run(){
		flag = true;
		while(flag) {
			try {
				indexWriter.commit();
				if (bprint) {
					System.out.println(new Date().toLocaleString() + "	" + IndexManagerName + "	commit");
				}
				TimeUnit.SECONDS.sleep(indexCommitSeconds);
			} catch (IOException e) {
				e.printStackTrace();
			} catch (InterruptedException e1) {
				e1.printStackTrace();
			}
		}
	}
}

this.indexCommitThread = new IndexCommitThread(IndexManagerName + "Index Commit Thread");
this.indexCommitThread.setDaemon(true);
this.indexCommitThread.start();

那又如何像普通的索引那样使用IndexSearcher呢？当然NrtManager类也提供了相关的方法，可以获取最新可用的IndexSearcher，代码如下：

public IndexSearcher getIndexSearcher(){
	try {
		return this.nrtManager.acquire();
	} catch (IOException e) {
		e.printStackTrace();
		return null;
	}
}

当然在使用之后别忘记释放，代码如下：

public void release(IndexSearcher searcher){
	try {
		nrtManager.release(searcher);
	} catch (IOException e) {
		// TODO Auto-generated catch block  
		e.printStackTrace();
	}
}

另类单例模式

在之前的博客中，我也多次提到，加载索引是一个相当消耗资源的事情，所以我们不可能每一次索引操作都加载一次索引，所以我们就必须使用单例模式来实现IndexManager类。这里的单例模式又和我们常见的单例模式有所区别，普通的单例模式该类只有一个对象，这里的单例模式是该类有多个对象，下面就简单的介绍下此处另类的单例模式。

通过前一篇博客最后，你也许会注意到，系统中关于索引的配置信息是存在HashSet对象中，这也就是说这里IndexManager类会实例化多少次取决于HashSet对象，也就是你配置文件让他实例化多少次就会实例化多少次。既然这样，怎么还能叫单例模式呢？这里的单例是索引的单例，也就是说一个索引只有一个IndexManager对象，不会存在两个IndexManager对象去操作同一个索引的情况。具体代码实现如下：

/**
 * Initialization on Demand Holder式初始化IndexManager
 */
private static class LazyLoadIndexManager {
	private static final HashMap<String, IndexManager> indexManager = new HashMap<String, IndexManager>();
	
	static {
		for (ConfigBean configBean : IndexConfig.getConfigBean()) {
			indexManager.put(configBean.getIndexName(), new IndexManager(configBean));
		}
	}
}

/**  
 *@Description: IndexManager私有构造方法
 *@Author: lulei  
 *@Version: 1.1.0  
 */
private IndexManager(ConfigBean configBean){
	//...
}
public static IndexManager getIndexManager(String indexName){
	return LazyLoadIndexManager.indexManager.get(indexName);
}

这样我们就可以通过索引名获取到该索引的IndexManager对象。

庐山真面目

说了这么多，下面就把IndexManager的源码附在最后，感兴趣的童鞋可以试试（里面还有一些其他的方法，相信不用介绍也都可以看的懂）

 /**  
 *@Description: 索引管理类   
 */ 
package com.lulei.lucene.index.manager;  

import java.io.File;
import java.io.IOException;
import java.util.Date;
import java.util.HashMap;
import java.util.concurrent.TimeUnit;

import org.apache.lucene.analysis.Analyzer;
import org.apache.lucene.index.IndexWriter;
import org.apache.lucene.index.IndexWriterConfig;
import org.apache.lucene.index.IndexWriterConfig.OpenMode;
import org.apache.lucene.search.IndexSearcher;
import org.apache.lucene.search.NRTManager;
import org.apache.lucene.search.NRTManager.TrackingIndexWriter;
import org.apache.lucene.search.NRTManagerReopenThread;
import org.apache.lucene.search.SearcherFactory;
import org.apache.lucene.store.Directory;
import org.apache.lucene.store.NIOFSDirectory;
import org.apache.lucene.util.Version;

import com.lulei.lucene.index.model.ConfigBean;
import com.lulei.lucene.index.model.IndexConfig;

public class IndexManager {

	private IndexWriter indexWriter;
	//更新索引文件的IndexWriter
	private TrackingIndexWriter trackingIndexWriter;
	//索引文件采用的分词器
	private Analyzer analyzer;
	//索引管理对象
	private NRTManager nrtManager;
	//索引重读线程
	private NRTManagerReopenThread nrtManagerReopenThread;
	//索引写入磁盘线程
	private IndexCommitThread indexCommitThread;
	
	//索引地址
	private String indexPath;
	//索引重读最大、最小时间间隔
	private double indexReopenMaxStaleSec;
	private double indexReopenMinStaleSec;
	//索引commit时间
	private int indexCommitSeconds;
	//索引名
	private String IndexManagerName;
	//commit时是否输出相关信息
	private boolean bprint = true;
	
	/**
	 * Initialization on Demand Holder式初始化IndexManager
	 */
	private static class LazyLoadIndexManager {
		private static final HashMap<String, IndexManager> indexManager = new HashMap<String, IndexManager>();
		
		static {
			for (ConfigBean configBean : IndexConfig.getConfigBean()) {
				indexManager.put(configBean.getIndexName(), new IndexManager(configBean));
			}
		}
	}
	
	/**  
	 *@Description: IndexManager私有构造方法
	 *@Author: lulei  
	 *@Version: 1.1.0  
	 */
	private IndexManager(ConfigBean configBean){
		//设置相关属性
		analyzer = configBean.getAnalyzer();
		indexPath = configBean.getIndexPath();
		IndexManagerName = configBean.getIndexName();
		indexReopenMaxStaleSec = configBean.getIndexReopenMaxStaleSec();
		indexReopenMinStaleSec = configBean.getIndexReopenMinStaleSec();
		indexCommitSeconds = configBean.getIndexCommitSeconds();
		bprint = configBean.isBprint();
		String indexFile = indexPath + IndexManagerName + "/";
		//创建或打开索引
		IndexWriterConfig indexWriterConfig = new IndexWriterConfig(Version.LUCENE_43, analyzer);
		indexWriterConfig.setOpenMode(OpenMode.CREATE_OR_APPEND);
		Directory directory = null;
		try {
			directory = NIOFSDirectory.open(new File(indexFile));
			if (IndexWriter.isLocked(directory)){
				IndexWriter.unlock(directory);
			}
			this.indexWriter = new IndexWriter(directory, indexWriterConfig);
			this.trackingIndexWriter = new TrackingIndexWriter(this.indexWriter);
			this.nrtManager = new NRTManager(this.trackingIndexWriter, new SearcherFactory());
		} catch(IOException e){
			e.printStackTrace();
		}
		//开启守护进程
		this.setThread();
	}
	/**
	 * @Author: lulei  
	 * @Description: 创建索引管理线程
	 */
	private void setThread(){
		this.nrtManagerReopenThread = new NRTManagerReopenThread(this.nrtManager, indexReopenMaxStaleSec, indexReopenMinStaleSec);
		this.nrtManagerReopenThread.setName("NRTManager Reopen Thread");
		this.nrtManagerReopenThread.setPriority(Math.min(Thread.currentThread().getPriority()+2, Thread.MAX_PRIORITY));
		this.nrtManagerReopenThread.setDaemon(true);
		this.nrtManagerReopenThread.start();
		
		this.indexCommitThread = new IndexCommitThread(IndexManagerName + "Index Commit Thread");
		this.indexCommitThread.setDaemon(true);
		this.indexCommitThread.start();
	}
	
	/**
	 * @return
	 * @Author:lulei  
	 * @Description: 重启索引commit线程
	 */
	public String setCommitThread() {
		try {
			if (this.indexCommitThread.isAlive()){
				return "is alive";
			}
			this.indexCommitThread = new IndexCommitThread(IndexManagerName + "Index Commit Thread");
			this.indexCommitThread.setDaemon(true);
			this.indexCommitThread.start();
		} catch (Exception e) {
			e.printStackTrace();
			return "failed";
		}
		return "reload";
	}
	
	/**
	 *@Description: 索引commit线程 
	 *@Author: lulei  
	 *@Version: 1.1.0
	 */
	private class IndexCommitThread extends Thread{
		private boolean flag;
		public IndexCommitThread(String name){
			super(name);
		}
		
		@SuppressWarnings("deprecation")
		public void run(){
			flag = true;
			while(flag) {
				try {
					indexWriter.commit();
					if (bprint) {
						System.out.println(new Date().toLocaleString() + "	" + IndexManagerName + "	commit");
					}
					TimeUnit.SECONDS.sleep(indexCommitSeconds);
				} catch (IOException e) {
					e.printStackTrace();
				} catch (InterruptedException e1) {
					e1.printStackTrace();
				}
			}
		}
	}
	
	
	/**
	 * @return IndexManager
	 * @Author: lulei  
	 * @Description: 获取索引管理类
	 */
	public static IndexManager getIndexManager(String indexName){
		return LazyLoadIndexManager.indexManager.get(indexName);
	}
	
	/**
	 * @@Description:释放IndexSearcher资源
	 * @param searcher
	 */
	public void release(IndexSearcher searcher){
		try {
			nrtManager.release(searcher);
		} catch (IOException e) {
			// TODO Auto-generated catch block  
			e.printStackTrace();
		}
	}
	
	/**
	 * @return IndexSearcher
	 * @Author: lulei  
	 * @Description: 返回IndexSearcher对象，使用完之后，调用release方法进行释放
	 */
	public IndexSearcher getIndexSearcher(){
		try {
			return this.nrtManager.acquire();
		} catch (IOException e) {
			e.printStackTrace();
			return null;
		}
	}
	
	public NRTManager getNRTManager(){
		return this.nrtManager;
	}
	
	public IndexWriter getIndexWriter(){
		return this.indexWriter;
	}
	
	public TrackingIndexWriter getTrackingIndexWriter(){
		return this.trackingIndexWriter;
	}
	
	public Analyzer getAnalyzer(){
		return analyzer;
	}
	
	/**
	 * @return
	 * @Author: lulei  
	 * @Description: 获取索引中的记录条数
	 */
	public int getIndexNum(){
		return indexWriter.numDocs();
	}
}

ps:最近发现其他网站可能会对博客转载，上面并没有源链接，如想查看更多关于基于lucene的案例开发请点击这里。或访问网址http://blog.csdn.net/xiaojimanman/article/category/2841877 或 www.llwjy.com