最近，需要对项目进行lucene版本升级。而原来项目时基于lucene 3.0的，很古老的一个版本的了。在老版本中中，我们主要用了几个lucene的东西：
1、查询lucene多目录索引。
2、构建RAMDirectory，把索引放到内存中，以提高检索效率。
3、构建Lucene自定义分词。
4、修改Lucene默认的打分算法。
下面，将代码改造前和改造后做一对比：
1. 搜索多索引目录
3.0 构建多索引目录：
1 // 初始化全国索引 2 private boolean InitGlobal(String strRootPath) { 3 try { 4 5 IndexSearcher[] searchers = new IndexSearcher[2]; 6 7 MultiSearcher globalSearcher = null; 8 if (Configution.IsMMap.equalsIgnoreCase("true")) { 9 10 searchers[0] = new IndexSearcher(new RAMDirectory(FSDirectory11 .open(new File(strRootPath + "/" + GLABOL_INDEX))));12 searchers[1] = new IndexSearcher(new RAMDirectory(FSDirectory13 .open(new File(strRootPath + "/" + BUS_INDEX))));14 // searchers[2] = new IndexSearcher(new RAMDirectory(FSDirectory15 // .open(new File(strRootPath + "/" + LU_INDEX))));16 globalSearcher = new MultiSearcher(searchers);17 } else {18 searchers[0] = new IndexSearcher(FSDirectory.open(new File(19 strRootPath + "/" + GLABOL_INDEX)));20 searchers[1] = new IndexSearcher(FSDirectory.open(new File(21 strRootPath + "/" + BUS_INDEX)));22 // searchers[2] = new IndexSearcher(FSDirectory.open(new File(23 // strRootPath + "/" + LU_INDEX)));24 25 globalSearcher = new MultiSearcher(searchers);26 }27 System.out.println("finish Global");28 29 m_mapIndexName2Searcher.put("0", globalSearcher);30 m_mapAdmin2IndexName.put("0", "0");31 32 return true;33 34 } catch (Exception e) {35 e.printStackTrace();36 SearchLog.SearchLog.error("全国索引初始化异常");37 return false;38 }39 } Ok，使用MultiSearcher，这是lucene低版本搜索多索引的解决方案。但是在高版本，MutiSearcher这个类本身都删除了，折腾我很长时间。可见以版本帝著称的Lucene代码设计不是太好。整个lucene代码，接口使用很少，大多是类和抽象类。
4.x 构建多索引目录：
// 初始化全国索引 private boolean InitGlobal(String strRootPath) { try { IndexSearcher globalSearcher = null; if (Configution.IsMMap.equalsIgnoreCase("true")) { IndexReader irGlobal = DirectoryReader.open(new RAMDirectory(FSDirectory .open(new File(strRootPath + "/" + GLABOL_INDEX)),new IOContext())); IndexReader irBus = DirectoryReader.open(new RAMDirectory(FSDirectory .open(new File(strRootPath + "/" + BUS_INDEX)),new IOContext())); MultiReader mr = new MultiReader(irGlobal,irBus); globalSearcher = new IndexSearcher(mr);//new MultiSearcher(searchers); } else { IndexReader irGlobal = DirectoryReader.open(FSDirectory .open(new File(strRootPath + "/" + GLABOL_INDEX))); IndexReader irBus = DirectoryReader.open(FSDirectory .open(new File(strRootPath + "/" + BUS_INDEX))); MultiReader mr = new MultiReader(irGlobal,irBus); globalSearcher = new IndexSearcher(mr);//new MultiSearcher(searchers); } System.out.println("finish Global"); m_mapIndexName2Searcher.put("0", globalSearcher); m_mapAdmin2IndexName.put("0", "0"); return true; } catch (Exception e) { e.printStackTrace(); SearchLog.SearchLog.error("全国索引初始化异常"); return false; } } ok 改造后，直接用IndexSearcher替代MultiSearcher，通过传入MultiReader来检索多个索引目录。
2、构建RAMDirectory，将索引放入内存中。
3.0 构建内存索引目录：
searchers[0] = new IndexSearcher(new RAMDirectory(FSDirectory .open(new File(strRootPath + "/" + GLABOL_INDEX)))); searchers[1] = new IndexSearcher(new RAMDirectory(FSDirectory .open(new File(strRootPath + "/" + BUS_INDEX))));
直接将Diretory作为RAMDirectory的构造函数，注意这个动作有坑，如果数据量大，你要等很久的！
4.x 构建内存索引目录：
IndexReader irGlobal = DirectoryReader.open(new RAMDirectory(FSDirectory .open(new File(strRootPath + "/" + GLABOL_INDEX)),new IOContext())); IndexReader irBus = DirectoryReader.open(new RAMDirectory(FSDirectory .open(new File(strRootPath + "/" + BUS_INDEX)),new IOContext())); MultiReader mr = new MultiReader(irGlobal,irBus);
在4.x中，安装3.0构造方法是不行的，还需要传入一个IOContext对象，汗~~~~~~~~~~~~~~~~
3、自定义分词：
3.0 自定义分词：
public class SingleAnalyzer extends Analyzer { /** * @param args */ public TokenStream tokenStream(String fieldName, Reader reader){ TokenStream result = null; if(fieldName.equals("name")) { result = new SingleTokenizer(reader); } if(fieldName.equals("totalcity")) { result = new IKTokenizer(reader, false); } // result = new StandardFilter(result);// result = new LowerCaseFilter(result); // result = new StopFilter(result, stopSet); return result; } public static void main(String[] args) { // TODO Auto-generated method stub }} 重写tokenStream方法即可，很简单。
4.x自定义分词：
public class SingleAnalyzer extends Analyzer { /** * @param args */ // public TokenStream tokenStream(String fieldName, Reader reader){// TokenStream result = null;// if(fieldName.equals("name"))// {// result = new SingleTokenizer(reader);// }// if(fieldName.equals("totalcity"))// {// result = new IKTokenizer(reader, false);// }// result = new StandardFilter(result); result = new LowerCaseFilter(result);// // result = new StopFilter(result, stopSet);// return result;// } @Override protected TokenStreamComponents createComponents(String fieldName, Reader reader) { // TODO Auto-generated method stub// final Tokenizer source = new ChineseTokenizer(reader);// return new TokenStreamComponents(source, new ChineseFilter(source)); Tokenizer source = null; if(fieldName.equals("name")){ source = new SingleTokenizer(reader); }else if(fieldName.equals("totalcity")){ source = new IKTokenizer(reader, false); } return new TokenStreamComponents(source, source); }} OK，在4.x中你需要重写createComponents方法。
4、打分算法：
3.x和4.x打分算法变化不大，但是命名空间发生了变化，汗~~~~~~~~~~~~
3.x 命名空间：引入：import org.apache.lucene.search.DefaultSimilarity，命名空间在：org.apache.lucene.search
4.x命名空间：引入：import org.apache.lucene.search.similarities.*，命名空间在：org.apache.lucene.search.similarities。
5、查询表达式：主要体现在TermRangeQuery上，3.x版本的一个参数是string类型，但是在4.x版本变成了包了string一层的BytesRef，还有其他很多细节变化
3.x TermRangerQuery：
1 String left = Long 2 .toString((long) (rcBound.m_dLeft * COORDINATE_SCALE_FACTOR)); 3 String right = Long 4 .toString((long) (rcBound.m_dRight * COORDINATE_SCALE_FACTOR)); 5 String top = Long 6 .toString((long) (rcBound.m_dTop * COORDINATE_SCALE_FACTOR)); 7 String bottom = Long 8 .toString((long) (rcBound.m_dBottom * COORDINATE_SCALE_FACTOR)); 9 10 11 12 TermRangeQuery query1 = new TermRangeQuery("lon", left, right,13 true, true);14 TermRangeQuery query2 = new TermRangeQuery("lat", bottom, top,15 true, true);16 searchQuery.add(query1, BooleanClause.Occur.MUST);17 searchQuery.add(query2, BooleanClause.Occur.MUST); 4.x TermRangerQuery：
String left = Long .toString((long) (rcBound.m_dLeft * COORDINATE_SCALE_FACTOR)); String right = Long .toString((long) (rcBound.m_dRight * COORDINATE_SCALE_FACTOR)); String top = Long .toString((long) (rcBound.m_dTop * COORDINATE_SCALE_FACTOR)); String bottom = Long .toString((long) (rcBound.m_dBottom * COORDINATE_SCALE_FACTOR)); BytesRef brLeft = new BytesRef(left); BytesRef brRight = new BytesRef(right); BytesRef brBottom = new BytesRef(bottom); BytesRef brTop = new BytesRef(top); TermRangeQuery query1 = new TermRangeQuery("lon", brLeft, brRight, true, true); TermRangeQuery query2 = new TermRangeQuery("lat", brBottom, brTop, true, true); searchQuery.add(query1, BooleanClause.Occur.MUST); searchQuery.add(query2, BooleanClause.Occur.MUST); 6、关闭IndexSearcher
3.x 关闭IndexSearcher直接调用close方法即可：
1 public void UnInit() { 2 if (!m_bIsInit) 3 return; 4 5 Iterator iter = m_mapIndexName2Searcher.keySet().iterator(); 6 7 while (iter.hasNext()) { 8 9 String key = (String) iter.next();10 11 MultiSearcher val = (MultiSearcher) m_mapIndexName2Searcher12 .get(key);13 14 try {15 16 val.close();//关闭IndexSearcher17 } catch (IOException e) {18 e.printStackTrace();19 SearchLog.SearchLog.error("分级索引关闭异常");20 }21 }22 23 m_mapIndexName2Searcher.clear();24 m_mapAdmin2IndexName.clear();25 m_mapIndexName2Searcher = null;26 m_mapAdmin2IndexName = null;27 m_bIsInit = false;28 } 4.x 关闭IndexSearcher 没有直接close的方法，需要getIndexReader 然后调用IndexReader的close方法：
1 public void UnInit() { 2 if (!m_bIsInit) 3 return; 4 5 Iterator iter = m_mapIndexName2Searcher.keySet().iterator(); 6 7 while (iter.hasNext()) { 8 9 String key = (String) iter.next();10 11 IndexSearcher val = (IndexSearcher) m_mapIndexName2Searcher12 .get(key);13 14 try {15 val.getIndexReader().close();//关闭IndexSearcher16 } catch (IOException e) {17 e.printStackTrace();18 SearchLog.SearchLog.error("分级索引关闭异常");19 }20 }21 22 m_mapIndexName2Searcher.clear();23 m_mapAdmin2IndexName.clear();24 m_mapIndexName2Searcher = null;25 m_mapAdmin2IndexName = null;26 m_bIsInit = false;27 } 总之，lucene版本变化很大，如果升级很多方法发送变化，您需要细致观察，多试试，才能升级。升级完成后，最好进行一次功能测试，有些功能可能发生变化甚至错误。升级Lucene不是一件好差事~~~~~~~~~
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