LIRe 源代码分析 3：基本接口（ImageSearcher）

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LIRe源代码分析系列文章列表：

LIRe 源代码分析 1：整体结构

LIRe 源代码分析 2：基本接口（DocumentBuilder）

LIRe 源代码分析 4：建立索引（DocumentBuilder）[以颜色布局为例]

LIRe 源代码分析 5：提取特征向量[以颜色布局为例]

LIRe 源代码分析 6：检索（ImageSearcher）[以颜色布局为例]

LIRe 源代码分析 7：算法类[以颜色布局为例]

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上篇文章介绍了LIRe源代码里的DocumentBuilder的几个基本接口。本文继续研究一下源代码里的ImageSearcher的几个基本接口。

下面来看看与ImageSearcher相关的类的定义：

ImageSearcher：接口，定义了基本的方法。

AbstractImageSearcher：纯虚类，实现了ImageSearcher接口。

ImageSearcherFactory：用于创建ImageSearcher。

ImageSearcher相关的类的继承关系如下图所示。可见，各种算法类都继承了AbstractImageSearcher，而AbstractImageSearcher实现了ImageSearcher接口。

此外还有一个结构体：

ImageSearchHits：用于存储搜索的结果。

详细的源代码如下所示：

ImageSearcher

/** This file is part of the LIRe project: http://www.semanticmetadata.net/lire* LIRe is free software; you can redistribute it and/or modify* it under the terms of the GNU General Public License as published by* the Free Software Foundation; either version 2 of the License, or* (at your option) any later version.** LIRe is distributed in the hope that it will be useful,* but WITHOUT ANY WARRANTY; without even the implied warranty of* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the* GNU General Public License for more details.** You should have received a copy of the GNU General Public License* along with LIRe; if not, write to the Free Software* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA** We kindly ask you to refer the following paper in any publication mentioning Lire:** Lux Mathias, Savvas A. Chatzichristofis. Lire: Lucene Image Retrieval 鈥�* An Extensible Java CBIR Library. In proceedings of the 16th ACM International* Conference on Multimedia, pp. 1085-1088, Vancouver, Canada, 2008** http://doi.acm.org/10.1145/1459359.1459577** Copyright statement:* --------------------* (c) 2002-2011 by Mathias Lux (mathias@juggle.at)*     http://www.semanticmetadata.net/lire*/package net.semanticmetadata.lire;import org.apache.lucene.document.Document;
import org.apache.lucene.index.IndexReader;import java.awt.image.BufferedImage;
import java.io.IOException;
import java.io.InputStream;
import java.util.Set;/*** <h2>Searching in an Index</h2>* Use the ImageSearcherFactory for creating an ImageSearcher, which will retrieve the images* for you from the index.* <p/>* <pre>* IndexReader reader = IndexReader.open(indexPath);* ImageSearcher searcher = ImageSearcherFactory.createDefaultSearcher();* FileInputStream imageStream = new FileInputStream("image.jpg");* BufferedImage bimg = ImageIO.read(imageStream);* // searching for an image:* ImageSearchHits hits = null;* hits = searcher.search(bimg, reader);* for (int i = 0; i < 5; i++) {* System.out.println(hits.score(i) + ": " + hits.doc(i).getField(DocumentBuilder.FIELD_NAME_IDENTIFIER).stringValue());* }** // searching for a document:* Document document = hits.doc(0);* hits = searcher.search(document, reader);* for (int i = 0; i < 5; i++) {* System.out.println(hits.score(i) + ": " + hits.doc(i).getField(DocumentBuilder.FIELD_NAME_IDENTIFIER).stringValue());* }* </pre>* <p/>* This file is part of the Caliph and Emir project: http://www.SemanticMetadata.net* <br>Date: 01.02.2006* <br>Time: 00:09:42** @author Mathias Lux, mathias@juggle.at*/
public interface ImageSearcher {/*** Searches for images similar to the given image.** @param image  the example image to search for.* @param reader the IndexReader which is used to dsearch through the images.* @return a sorted list of hits.* @throws java.io.IOException in case exceptions in the reader occurs*/public ImageSearchHits search(BufferedImage image, IndexReader reader) throws IOException;/*** Searches for images similar to the given image, defined by the Document from the index.** @param doc    the example image to search for.* @param reader the IndexReader which is used to dsearch through the images.* @return a sorted list of hits.* @throws java.io.IOException in case exceptions in the reader occurs*/public ImageSearchHits search(Document doc, IndexReader reader) throws IOException;/*** Searches for images similar to the given image.** @param image  the example image to search for.* @param reader the IndexReader which is used to dsearch through the images.* @return a sorted list of hits.* @throws IOException in case the image could not be read from stream.*/public ImageSearchHits search(InputStream image, IndexReader reader) throws IOException;/*** Identifies duplicates in the database.** @param reader the IndexReader which is used to dsearch through the images.* @return a sorted list of hits.* @throws IOException in case the image could not be read from stream.*/public ImageDuplicates findDuplicates(IndexReader reader) throws IOException;/*** Modifies the given search by the provided positive and negative examples. This process follows the idea* of relevance feedback.** @param originalSearch* @param positives* @param negatives* @return*/public ImageSearchHits relevanceFeedback(ImageSearchHits originalSearch,Set<Document> positives, Set<Document> negatives);
}

从接口的源代码可以看出，提供了5个方法，其中有3个名字都叫search()，只是参数不一样。一个是BufferedImage，一个是Document，而另一个是InputStream。

AbstractImageSearcher

/** This file is part of the LIRe project: http://www.semanticmetadata.net/lire* LIRe is free software; you can redistribute it and/or modify* it under the terms of the GNU General Public License as published by* the Free Software Foundation; either version 2 of the License, or* (at your option) any later version.** LIRe is distributed in the hope that it will be useful,* but WITHOUT ANY WARRANTY; without even the implied warranty of* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the* GNU General Public License for more details.** You should have received a copy of the GNU General Public License* along with LIRe; if not, write to the Free Software* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA** We kindly ask you to refer the following paper in any publication mentioning Lire:** Lux Mathias, Savvas A. Chatzichristofis. Lire: Lucene Image Retrieval 鈥�* An Extensible Java CBIR Library. In proceedings of the 16th ACM International* Conference on Multimedia, pp. 1085-1088, Vancouver, Canada, 2008** http://doi.acm.org/10.1145/1459359.1459577** Copyright statement:* --------------------* (c) 2002-2011 by Mathias Lux (mathias@juggle.at)*     http://www.semanticmetadata.net/lire*/
package net.semanticmetadata.lire;import org.apache.lucene.document.Document;
import org.apache.lucene.index.IndexReader;import javax.imageio.ImageIO;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.io.InputStream;
import java.util.Set;/*** Abstract ImageSearcher, which uses javax.imageio.ImageIO to create a BufferedImage* from an InputStream.* <p/>* This file is part of the Caliph and Emir project: http://www.SemanticMetadata.net* <br>Date: 01.02.2006* <br>Time: 00:13:16** @author Mathias Lux, mathias@juggle.at*/
public abstract class AbstractImageSearcher implements ImageSearcher {/*** Searches for images similar to the given image. This simple implementation uses* {@link ImageSearcher#search(java.awt.image.BufferedImage, org.apache.lucene.index.IndexReader)},* the image is read using javax.imageio.ImageIO.** @param image  the example image to search for.* @param reader the IndexReader which is used to dsearch through the images.* @return a sorted list of hits.* @throws IOException in case the image could not be read from stream.*/public ImageSearchHits search(InputStream image, IndexReader reader) throws IOException {BufferedImage bufferedImage = ImageIO.read(image);return search(bufferedImage, reader);}public ImageSearchHits relevanceFeedback(ImageSearchHits originalSearch, Set<Document> positives, Set<Document> negatives) {throw new UnsupportedOperationException("Not implemented yet for this kind of searcher!");}
}

从代码中可以看出AbstractImageSearcher实现了ImageSearcher接口。其中的search(InputStream image, IndexReader reader)方法调用了search(BufferedImage image, IndexReader reader)方法。说白了，就是把2个函数的功能合并为一个函数。

ImageSearcherFactory

/** This file is part of the LIRe project: http://www.semanticmetadata.net/lire* LIRe is free software; you can redistribute it and/or modify* it under the terms of the GNU General Public License as published by* the Free Software Foundation; either version 2 of the License, or* (at your option) any later version.** LIRe is distributed in the hope that it will be useful,* but WITHOUT ANY WARRANTY; without even the implied warranty of* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the* GNU General Public License for more details.** You should have received a copy of the GNU General Public License* along with LIRe; if not, write to the Free Software* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA** We kindly ask you to refer the following paper in any publication mentioning Lire:** Lux Mathias, Savvas A. Chatzichristofis. Lire: Lucene Image Retrieval 鈥�* An Extensible Java CBIR Library. In proceedings of the 16th ACM International* Conference on Multimedia, pp. 1085-1088, Vancouver, Canada, 2008** http://doi.acm.org/10.1145/1459359.1459577** Copyright statement:* ~~~~~~~~~~~~~~~~~~~~* (c) 2002-2011 by Mathias Lux (mathias@juggle.at)*     http://www.semanticmetadata.net/lire*/package net.semanticmetadata.lire;import net.semanticmetadata.lire.imageanalysis.*;
import net.semanticmetadata.lire.impl.CorrelogramImageSearcher;
import net.semanticmetadata.lire.impl.GenericFastImageSearcher;
import net.semanticmetadata.lire.impl.SimpleImageSearcher;/*** <h2>Searching in an Index</h2>* Use the ImageSearcherFactory for creating an ImageSearcher, which will retrieve the images* for you from the index.* <p/>* <pre>* IndexReader reader = IndexReader.open(indexPath);* ImageSearcher searcher = ImageSearcherFactory.createDefaultSearcher();* FileInputStream imageStream = new FileInputStream("image.jpg");* BufferedImage bimg = ImageIO.read(imageStream);* // searching for an image:* ImageSearchHits hits = null;* hits = searcher.search(bimg, reader);* for (int i = 0; i < 5; i++) {* System.out.println(hits.score(i) + ": " + hits.doc(i).getField(DocumentBuilder.FIELD_NAME_IDENTIFIER).stringValue());* }** // searching for a document:* Document document = hits.doc(0);* hits = searcher.search(document, reader);* for (int i = 0; i < 5; i++) {* System.out.println(hits.score(i) + ": " + hits.doc(i).getField(DocumentBuilder.FIELD_NAME_IDENTIFIER).stringValue());* }* </pre>* <p/>* This file is part of the Caliph and Emir project: http://www.SemanticMetadata.net* <br>Date: 03.02.2006* <br>Time: 00:30:07** @author Mathias Lux, mathias@juggle.at*/
public class ImageSearcherFactory {/*** Default number of maximum hits.*/public static int NUM_MAX_HITS = 100;/*** Creates a new simple image searcher with the desired number of maximum hits.** @param maximumHits* @return the searcher instance* @deprecated Use ColorLayout, EdgeHistogram and ScalableColor features instead.*/public static ImageSearcher createSimpleSearcher(int maximumHits) {return ImageSearcherFactory.createColorLayoutImageSearcher(maximumHits);}/*** Returns a new default ImageSearcher with a predefined number of maximum* hits defined in the {@link ImageSearcherFactory#NUM_MAX_HITS} based on the {@link net.semanticmetadata.lire.imageanalysis.CEDD} feature** @return the searcher instance*/public static ImageSearcher createDefaultSearcher() {return new GenericFastImageSearcher(NUM_MAX_HITS, CEDD.class, DocumentBuilder.FIELD_NAME_CEDD);}/*** Returns a new ImageSearcher with the given number of maximum hits* which only takes the overall color into account. texture and color* distribution are ignored.** @param maximumHits defining how many hits are returned in max (e.g. 100 would be ok)* @return the ImageSearcher* @see ImageSearcher* @deprecated Use ColorHistogram or ScalableColor instead*/public static ImageSearcher createColorOnlySearcher(int maximumHits) {return ImageSearcherFactory.createScalableColorImageSearcher(maximumHits);}/*** Returns a new ImageSearcher with the given number of maximum hits and* the specified weights on the different matching aspects. All weights* should be in [0,1] whereas a weight of 0 implies that the feature is* not taken into account for searching. Note that the effect is relative and* can only be fully applied if the {@link DocumentBuilderFactory#getExtensiveDocumentBuilder() extensive DocumentBuilder}* is used.** @param maximumHits             defining how many hits are returned in max* @param colorHistogramWeight    a weight in [0,1] defining the importance of overall color in the images* @param colorDistributionWeight a weight in [0,1] defining the importance of color distribution (which color where) in the images* @param textureWeight           defining the importance of texture (which edges where) in the images* @return the searcher instance or NULL if the weights are not appropriate, eg. all 0 or not in [0,1]* @see DocumentBuilderFactory* @deprecated Use ColorLayout, EdgeHistogram and ScalableColor features instead.*/public static ImageSearcher createWeightedSearcher(int maximumHits,float colorHistogramWeight,float colorDistributionWeight,float textureWeight) {if (isAppropriateWeight(colorHistogramWeight)&& isAppropriateWeight(colorDistributionWeight)&& isAppropriateWeight(textureWeight)&& (colorHistogramWeight + colorDistributionWeight + textureWeight > 0f))return new SimpleImageSearcher(maximumHits, colorHistogramWeight, colorDistributionWeight, textureWeight);elsereturn null;}/*** Create and return an ImageSearcher for the {@link net.semanticmetadata.lire.imageanalysis.AutoColorCorrelogram}* image feature. Be sure to use the same options for the ImageSearcher as you used for the DocumentBuilder.** @param maximumHits number of hits returned.* @return*/public static ImageSearcher createAutoColorCorrelogramImageSearcher(int maximumHits) {return new GenericFastImageSearcher(maximumHits, AutoColorCorrelogram.class, DocumentBuilder.FIELD_NAME_AUTOCOLORCORRELOGRAM);
//        return new CorrelogramImageSearcher(maximumHits, AutoColorCorrelogram.Mode.SuperFast);}/*** Create and return an ImageSearcher for the {@link net.semanticmetadata.lire.imageanalysis.AutoColorCorrelogram}* image feature. Be sure to use the same options for the ImageSearcher as you used for the DocumentBuilder.** @param maximumHits number of hits returned.* @return* @deprecated Use #createAutoColorCorrelogramImageSearcher instead*/public static ImageSearcher createFastCorrelogramImageSearcher(int maximumHits) {return new CorrelogramImageSearcher(maximumHits, AutoColorCorrelogram.Mode.SuperFast);}/*** Create and return an ImageSearcher for the {@link net.semanticmetadata.lire.imageanalysis.CEDD}* image feature. Be sure to use the same options for the ImageSearcher as you used for the DocumentBuilder.** @param maximumHits* @return*/public static ImageSearcher createCEDDImageSearcher(int maximumHits) {
//        return new CEDDImageSearcher(maximumHits);return new GenericFastImageSearcher(maximumHits, CEDD.class, DocumentBuilder.FIELD_NAME_CEDD);}/*** Create and return an ImageSearcher for the {@link net.semanticmetadata.lire.imageanalysis.FCTH}* image feature. Be sure to use the same options for the ImageSearcher as you used for the DocumentBuilder.** @param maximumHits* @return*/public static ImageSearcher createFCTHImageSearcher(int maximumHits) {
//        return new GenericImageSearcher(maximumHits, FCTH.class, DocumentBuilder.FIELD_NAME_FCTH);return new GenericFastImageSearcher(maximumHits, FCTH.class, DocumentBuilder.FIELD_NAME_FCTH);}/*** Create and return an ImageSearcher for the {@link net.semanticmetadata.lire.imageanalysis.JCD}* image feature. Be sure to use the same options for the ImageSearcher as you used for the DocumentBuilder.** @param maximumHits* @return*/public static ImageSearcher createJCDImageSearcher(int maximumHits) {return new GenericFastImageSearcher(maximumHits, JCD.class, DocumentBuilder.FIELD_NAME_JCD);}/*** Create and return an ImageSearcher for the {@link net.semanticmetadata.lire.imageanalysis.JpegCoefficientHistogram}* image feature. Be sure to use the same options for the ImageSearcher as you used for the DocumentBuilder.** @param maximumHits* @return*/public static ImageSearcher createJpegCoefficientHistogramImageSearcher(int maximumHits) {return new GenericFastImageSearcher(maximumHits, JpegCoefficientHistogram.class, DocumentBuilder.FIELD_NAME_JPEGCOEFFS);}/*** Create and return an ImageSearcher for the {@link net.semanticmetadata.lire.imageanalysis.SimpleColorHistogram}* image feature. Be sure to use the same options for the ImageSearcher as you used for the DocumentBuilder.** @param maximumHits* @return*/public static ImageSearcher createColorHistogramImageSearcher(int maximumHits) {
//        return new GenericImageSearcher(maximumHits, SimpleColorHistogram.class, DocumentBuilder.FIELD_NAME_COLORHISTOGRAM);return new GenericFastImageSearcher(maximumHits, SimpleColorHistogram.class, DocumentBuilder.FIELD_NAME_COLORHISTOGRAM);}/*** Create and return an ImageSearcher for the {@link net.semanticmetadata.lire.imageanalysis.Tamura}* image feature. Be sure to use the same options for the ImageSearcher as you used for the DocumentBuilder.** @param maximumHits* @return*/public static ImageSearcher createTamuraImageSearcher(int maximumHits) {return new GenericFastImageSearcher(maximumHits, Tamura.class, DocumentBuilder.FIELD_NAME_TAMURA);}/*** Create and return an ImageSearcher for the {@link net.semanticmetadata.lire.imageanalysis.Gabor}* image feature. Be sure to use the same options for the ImageSearcher as you used for the DocumentBuilder.** @param maximumHits* @return*/public static ImageSearcher createGaborImageSearcher(int maximumHits) {return new GenericFastImageSearcher(maximumHits, Gabor.class, DocumentBuilder.FIELD_NAME_GABOR);}/*** Create and return an ImageSearcher for the {@link net.semanticmetadata.lire.imageanalysis.ColorLayout}* image feature using the byte[] serialization. Be sure to use the same options for the ImageSearcher as* you used for the DocumentBuilder.** @param maximumHits* @return*/public static ImageSearcher createColorLayoutImageSearcher(int maximumHits) {return new GenericFastImageSearcher(maximumHits, ColorLayout.class, DocumentBuilder.FIELD_NAME_COLORLAYOUT);}/*** Create and return an ImageSearcher for the {@link net.semanticmetadata.lire.imageanalysis.ScalableColor}* image feature using the byte[] serialization. Be sure to use the same options for the ImageSearcher as* you used for the DocumentBuilder.** @param maximumHits* @return*/public static ImageSearcher createScalableColorImageSearcher(int maximumHits) {return new GenericFastImageSearcher(maximumHits, ScalableColor.class, DocumentBuilder.FIELD_NAME_SCALABLECOLOR);}/*** Create and return an ImageSearcher for the {@link net.semanticmetadata.lire.imageanalysis.EdgeHistogram}* image feature using the byte[] serialization. Be sure to use the same options for the ImageSearcher as* you used for the DocumentBuilder.** @param maximumHits* @return*/public static ImageSearcher createEdgeHistogramImageSearcher(int maximumHits) {return new GenericFastImageSearcher(maximumHits, EdgeHistogram.class, DocumentBuilder.FIELD_NAME_EDGEHISTOGRAM);}/*** Checks if the weight is in [0,1]** @param f the weight to check* @return true if the weight is in [0,1], false otherwise*/private static boolean isAppropriateWeight(float f) {boolean result = false;if (f <= 1f && f >= 0) result = true;return result;}
}

ImageSearcherFactory是用于创建ImageSearcher的。里面有各种create****ImageSearcher()。每个函数的作用在注释中都有详细的说明。

ImageSearchHits

/** This file is part of the LIRe project: http://www.semanticmetadata.net/lire* LIRe is free software; you can redistribute it and/or modify* it under the terms of the GNU General Public License as published by* the Free Software Foundation; either version 2 of the License, or* (at your option) any later version.** LIRe is distributed in the hope that it will be useful,* but WITHOUT ANY WARRANTY; without even the implied warranty of* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the* GNU General Public License for more details.** You should have received a copy of the GNU General Public License* along with LIRe; if not, write to the Free Software* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA** We kindly ask you to refer the following paper in any publication mentioning Lire:** Lux Mathias, Savvas A. Chatzichristofis. Lire: Lucene Image Retrieval 鈥�* An Extensible Java CBIR Library. In proceedings of the 16th ACM International* Conference on Multimedia, pp. 1085-1088, Vancouver, Canada, 2008** http://doi.acm.org/10.1145/1459359.1459577** Copyright statement:* --------------------* (c) 2002-2011 by Mathias Lux (mathias@juggle.at)*     http://www.semanticmetadata.net/lire*/package net.semanticmetadata.lire;import org.apache.lucene.document.Document;/*** This class simulates the original Lucene Hits object.* Please note the only a certain number of results are returned.<br>* <p/>* This file is part of the Caliph and Emir project: http://www.SemanticMetadata.net* <br>Date: 02.02.2006* <br>Time: 23:45:20** @author Mathias Lux, mathias@juggle.at*/
public interface ImageSearchHits {/*** Returns the size of the result list.** @return the size of the result list.*/public int length();/*** Returns the score of the document at given position.* Please note that the score in this case is a distance,* which means a score of 0 denotes the best possible hit.* The result list starts with position 0 as everything* in computer science does.** @param position defines the position* @return the score of the document at given position. The lower the better (its a distance measure).*/public float score(int position);/*** Returns the document at given position** @param position defines the position.* @return the document at given position.*/public Document doc(int position);
}

该类主要用于存储ImageSearcher类中search()方法返回的结果。

SimpleImageSearchHits是ImageSearcher的实现。该类的源代码如下所示：

/** This file is part of the LIRe project: http://www.semanticmetadata.net/lire* LIRe is free software; you can redistribute it and/or modify* it under the terms of the GNU General Public License as published by* the Free Software Foundation; either version 2 of the License, or* (at your option) any later version.** LIRe is distributed in the hope that it will be useful,* but WITHOUT ANY WARRANTY; without even the implied warranty of* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the* GNU General Public License for more details.** You should have received a copy of the GNU General Public License* along with LIRe; if not, write to the Free Software* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA** We kindly ask you to refer the following paper in any publication mentioning Lire:** Lux Mathias, Savvas A. Chatzichristofis. Lire: Lucene Image Retrieval 鈥�* An Extensible Java CBIR Library. In proceedings of the 16th ACM International* Conference on Multimedia, pp. 1085-1088, Vancouver, Canada, 2008** http://doi.acm.org/10.1145/1459359.1459577** Copyright statement:* --------------------* (c) 2002-2011 by Mathias Lux (mathias@juggle.at)*     http://www.semanticmetadata.net/lire*/package net.semanticmetadata.lire.impl;import net.semanticmetadata.lire.ImageSearchHits;
import org.apache.lucene.document.Document;import java.util.ArrayList;
import java.util.Collection;
import java.util.Iterator;/*** This file is part of the Caliph and Emir project: http://www.SemanticMetadata.net* <br>Date: 02.02.2006* <br>Time: 23:56:15** @author Mathias Lux, mathias@juggle.at*/
public class SimpleImageSearchHits implements ImageSearchHits {ArrayList<SimpleResult> results;public SimpleImageSearchHits(Collection<SimpleResult> results, float maxDistance) {this.results = new ArrayList<SimpleResult>(results.size());this.results.addAll(results);// this step normalizes and inverts the distance ...// although its now a score or similarity like measure its further called distancefor (Iterator<SimpleResult> iterator = this.results.iterator(); iterator.hasNext(); ) {SimpleResult result = iterator.next();result.setDistance(1f - result.getDistance() / maxDistance);}}/*** Returns the size of the result list.** @return the size of the result list.*/public int length() {return results.size();}/*** Returns the score of the document at given position.* Please note that the score in this case is a distance,* which means a score of 0 denotes the best possible hit.* The result list starts with position 0 as everything* in computer science does.** @param position defines the position* @return the score of the document at given position. The lower the better (its a distance measure).*/public float score(int position) {return results.get(position).getDistance();}/*** Returns the document at given position** @param position defines the position.* @return the document at given position.*/public Document doc(int position) {return results.get(position).getDocument();}private float sigmoid(float f) {double result = 0f;result = -1d + 2d / (1d + Math.exp(-2d * f / 0.6));return (float) (1d - result);}
}

可以看出检索的结果是存在名为results的ArrayList<SimpleResult> 类型的变量中的。

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