sortextendsearch.java

Lucene+nuctch一书的全部源码 测试源码 和几个简单的项目

package chapter7;

import org.apache.lucene.index.Term;
import org.apache.lucene.index.TermEnum;
import org.apache.lucene.index.TermDocs;

import org.apache.lucene.search.ScoreDoc;
import org.apache.lucene.search.SortField;
import org.apache.lucene.index.IndexReader;

import org.apache.lucene.search.SortComparatorSource;
import org.apache.lucene.search.ScoreDocComparator;

import java.io.IOException;

// SortExtendSearch 实现SortComparatorSource接口，用来测试自定义排序，
// 根据索引中的不同水果历史价格变化情况，按照价格波动的大小进行排序
public class SortExtendSearch implements SortComparatorSource {

	private float last;  // 历史价格
	private float stat;  // 当前价格
	private float next;  // 预测价格

	// 默认构造函数
	public SortExtendSearch(){  
		this.last = 0;
		this.next = 0;
		this.stat = 0;
	}
	
	// 带输入参数的构造函数
	public SortExtendSearch(float last,float stat, float next) {
		this.last = last;
		this.stat = stat;
		this.next = next;
	}
	
	/*================================================================
	 * 返回ScoreDocComparator 用来实现排序功能
	 *================================================================*/	
	public ScoreDocComparator newComparator(IndexReader reader, String sortname)
	throws IOException {
		return new PriceScoreDocComparator(reader, sortname, last,stat, next);
	}

	/*================================================================
	 * PriceScoreDocComparator 实现了ScoreDocComparator 用来对价格浮动情况进行排序
	 *================================================================*/	
	private static class PriceScoreDocComparator implements ScoreDocComparator {
		
		private float[] markup; // 保存每个商品历史价格波动幅度
	
		// 实现了ScoreDocComparator接口的构造函数
		public PriceScoreDocComparator(IndexReader reader,String sortname, float last,float stat, float next) 
		 throws IOException {
			final TermEnum enumerator = reader.terms(new Term(sortname, "")); // 索引项枚举器
			
			markup = new float[reader.maxDoc()];              // 初始化markup数组
			
			if (markup.length > 0) {
					TermDocs termDocs = reader.termDocs();
					try {
						if (enumerator.term() == null) {
							throw new RuntimeException("no terms in field "	+ sortname);
						}
						
						int i = 0,j = 0;
						do {
							Term term = enumerator.term();   // 取出每一个Term 
							if (term.field() != sortname)    // 与给定的域不符合则停止比较
								break;
							termDocs.seek(enumerator);       // 定位枚举器
							while (termDocs.next()) {        // 循环取枚举器内每一个TermDocs
								String[] pricedis = term.text().split(","); 
								float price1 = Float.parseFloat( pricedis[0] ) - last;
								float price2 = Float.parseFloat( pricedis[1] ) - stat;
								float price3 = Float.parseFloat( pricedis[2] ) - next;
								
								// 计算价格变动幅度
								markup[termDocs.doc()] = (price3 - price2) - (price2 - price1) ;
							}
						} while (enumerator.next());
				
				} finally {
					termDocs.close();
				}
			}
		}
	
		// 定义排序的比较函数
		public int compare(ScoreDoc i, ScoreDoc j) {
			if (markup[i.doc] < markup[j.doc])
				return -1;
			if (markup[i.doc] > markup[j.doc])
				return 1;
			return 0;
		}
	
		// 返回排序的结果
		public Comparable sortValue(ScoreDoc data) {
			return new Float(markup[data.doc]);
		}
		// 指定接口的排序类型
		public int sortType() {
			return SortField.FLOAT;
		}
	}

	// 输出对象的内部变量
	public String toString() {
		return "Price makeup (" + last + "," + stat+ "," + next + ")";
	}
	// 测试方法
	public static void main(String[] args) throws IOException{
		SortExtendSearch sortext = new SortExtendSearch();
		System.out.println(sortext.toString());
	}
}