SmartChineseAnalyzer的对中文开源社区是一大贡献
转自 ： SmartChineseAnalyzer_java - imdict-chinese-analyzer - Project Hosting on Google Code.htm
欣喜的看到在lucene 3.0里已经集成进了SmartChineseAnalyzer这个基于隐马尔科夫模型的中文分词模块，绝对是对中文开源社区的一大贡献。绝对得支持啊！
| /** |
| * Copyright 2009 www.imdict.net |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| package org.apache.lucene.analysis.cn; |
| import java.io.BufferedReader; |
| import java.io.IOException; |
| import java.io.InputStream; |
| import java.io.InputStreamReader; |
| import java.io.Reader; |
| import java.util.HashSet; |
| import java.util.Set; |
| import org.apache.lucene.analysis.Analyzer; |
| import org.apache.lucene.analysis.PorterStemFilter; |
| import org.apache.lucene.analysis.StopFilter; |
| import org.apache.lucene.analysis.TokenStream; |
| import org.apache.lucene.analysis.cn.smart.SentenceTokenizer; |
| import org.apache.lucene.analysis.cn.smart.WordSegmenter; |
| import org.apache.lucene.analysis.cn.smart.WordTokenizer; |
| /** |
| * |
| * SmartChineseAnalyzer 是一个智能中文分词模块， 能够利用概率对汉语句子进行最优切分， |
| * 并内嵌英文tokenizer，能有效处理中英文混合的文本内容。 |
| * |
| * 它的原理基于自然语言处理领域的隐马尔科夫模型(HMM)， 利用大量语料库的训练来统计汉语词汇的词频和跳转概率， |
| * 从而根据这些统计结果对整个汉语句子计算最似然(likelihood)的切分。 |
| * |
| * 因为智能分词需要词典来保存词汇的统计值，SmartChineseAnalyzer的运行需要指定词典位置，如何指定词典位置请参考 |
| * org.apache.lucene.analysis.cn.smart.AnalyzerProfile |
| * |
| * SmartChineseAnalyzer的算法和语料库词典来自于ictclas1.0项目(http://www.ictclas.org)， |
| * 其中词典已获取www.ictclas.org的apache license v2(APLv2)的授权。在遵循APLv2的条件下，欢迎用户使用。 |
| * 在此感谢www.ictclas.org以及ictclas分词软件的工作人员的无私奉献！ |
| * |
| * @see org.apache.lucene.analysis.cn.smart.AnalyzerProfile |
| * |
| */ |
| public class SmartChineseAnalyzer extends Analyzer { |
| private Set<String> stopWords = null; |
| private WordSegmenter wordSegment; |
| public SmartChineseAnalyzer() { |
| this(false); |
| } |
| /** |
| * SmartChineseAnalyzer内部带有默认停止词库，主要是标点符号。如果不希望结果中出现标点符号， |
| * 可以将useDefaultStopWords设为true， useDefaultStopWords为false时不使用任何停止词 |
| * |
| * @param useDefaultStopWords |
| */ |
| public SmartChineseAnalyzer(boolean useDefaultStopWords) { |
| if (useDefaultStopWords) { |
| stopWords = loadStopWords(this.getClass().getResourceAsStream( |
| "stopwords.txt")); |
| } |
| wordSegment = new WordSegmenter(); |
| } |
| /** |
| * 使用自定义的而不使用内置的停止词库，停止词可以使用SmartChineseAnalyzer.loadStopWords(InputStream)加载 |
| * |
| * @param stopWords |
| * @see SmartChineseAnalyzer.loadStopWords(InputStream) |
| */ |
| public SmartChineseAnalyzer(Set<String> stopWords) { |
| this.stopWords = stopWords; |
| wordSegment = new WordSegmenter(); |
| } |
| public TokenStream tokenStream(String fieldName, Reader reader) { |
| TokenStream result = new SentenceTokenizer(reader); |
| result = new WordTokenizer(result, wordSegment); |
| // result = new LowerCaseFilter(result); |
| // 不再需要LowerCaseFilter，因为SegTokenFilter已经将所有英文字符转换成小写 |
| // stem太严格了, This is not bug, this feature:) |
| result = new PorterStemFilter(result); |
| if (stopWords != null) { |
| result = new StopFilter(result, stopWords, false); |
| } |
| return result; |
| } |
| /** |
| * 从停用词文件中加载停用词， 停用词文件是普通UTF-8编码的文本文件， 每一行是一个停用词，注释利用“//”， 停用词中包括中文标点符号， 中文空格， |
| * 以及使用率太高而对索引意义不大的词。 |
| * |
| * @param input 停用词文件 |
| * @return 停用词组成的HashSet |
| */ |
| public static Set<String> loadStopWords(InputStream input) { |
| String line; |
| Set<String> stopWords = new HashSet<String>(); |
| try { |
| BufferedReader br = new BufferedReader(new InputStreamReader(input, |
| "UTF-8")); |
| while ((line = br.readLine()) != null) { |
| if (line.indexOf("//") != -1) { |
| line = line.substring(0, line.indexOf("//")); |
| } |
| line = line.trim(); |
| if (line.length() != 0) |
| stopWords.add(line.toLowerCase()); |
| } |
| br.close(); |
| } catch (IOException e) { |
| System.err.println("WARNING: cannot open stop words list!"); |
| } |
| return stopWords; |
| } |
| } |