搜索结果排序

3，排序
默认是相关度排序。
也可以按指定的字段排序。

package cn.itcast.g_sort;

import java.util.ArrayList;
import java.util.List;

import org.apache.lucene.document.Document;
import org.apache.lucene.document.Field;
import org.apache.lucene.document.Field.Index;
import org.apache.lucene.document.Field.Store;
import org.apache.lucene.index.IndexWriter;
import org.apache.lucene.index.IndexWriter.MaxFieldLength;
import org.apache.lucene.queryParser.MultiFieldQueryParser;
import org.apache.lucene.queryParser.QueryParser;
import org.apache.lucene.search.IndexSearcher;
import org.apache.lucene.search.Query;
import org.apache.lucene.search.Sort;
import org.apache.lucene.search.SortField;
import org.apache.lucene.search.TopDocs;
import org.apache.lucene.search.highlight.Formatter;
import org.apache.lucene.search.highlight.Highlighter;
import org.apache.lucene.search.highlight.QueryScorer;
import org.apache.lucene.search.highlight.Scorer;
import org.apache.lucene.search.highlight.SimpleFragmenter;
import org.apache.lucene.search.highlight.SimpleHTMLFormatter;
import org.apache.lucene.util.Version;
import org.junit.Test;

import cn.itcast._domain.Article;
import cn.itcast._util.ArticleDocumentUtils;
import cn.itcast._util.LuceneUtils;

public class TestApp {

    // 建立索引
    @Test
    public void testCreateIndex() throws Exception {
        // 准备数据
        Article article = new Article();
        article.setId(30);
        article.setTitle("准备Lucene的开发环境");
        article.setContent("如果信息检索系统在用户发出了检索请求后再去互联网上找答案，根本无法在有限的时间内返回结果。");

        // 放到索引库中
        // 1, 把Article转为Document
        Document doc = ArticleDocumentUtils.articleToDocument(article);

        doc.setBoost(0.5F); // 1F表示正常得分，大于1表示高分，小于1表示低分

        // 2, 把Document放到索引库中
        LuceneUtils.getIndexWriter().addDocument(doc);
        LuceneUtils.getIndexWriter().commit();
    }

    // 搜索
    @Test
    public void testSearch() throws Exception {
        // 准备查询条件
        String queryString = "lucene";

        // 执行搜索
        List<Article> list = new ArrayList<Article>();

        // 1，把查询字符串转为Query对象（从title和content中查询）
        QueryParser queryParser = new MultiFieldQueryParser(Version.LUCENE_30, new String[] { "title", "content" }, LuceneUtils.getAnalyzer());
        Query query = queryParser.parse(queryString);

        // 2，执行查询，得到中间结果
        IndexSearcher indexSearcher = new IndexSearcher(LuceneUtils.getDirectory()); // 指定所用的索引库
        // TopDocs topDocs = indexSearcher.search(query, 100); // 最多返回前n条结果

        // ========================================================================================== 【创建高亮器】
        // indexSearcher.search(query, n);
        // indexSearcher.search(query, filter, n);
        // indexSearcher.search(query, filter, n, sort);

        // Sort sort = new Sort( new SortField("id", SortField.INT) ); // 按id升序排列
        Sort sort = new Sort(new SortField("id", SortField.INT, true)); // 按id降序排列（true表示降序，false表示升序）

        TopDocs topDocs = indexSearcher.search(query, null, 100, sort);

        // ==========================================================================================

        // 3，处理结果
        for (int i = 0; i < topDocs.scoreDocs.length; i++) {
            float score = topDocs.scoreDocs[i].score;
            System.out.println("---> score : " + score);

            // 根据编号拿到Document数据
            int docId = topDocs.scoreDocs[i].doc; // Document的内部编号
            Document doc = indexSearcher.doc(docId);
            // 把Document转为Article
            Article article = ArticleDocumentUtils.documentToArticle(doc);
            list.add(article);
        }
        indexSearcher.close();

        // 显示结果
        System.out.println("总结果数：" + list.size());
        for (Article a : list) {
            System.out.println("------------------------------");
            System.out.println("id = " + a.getId());
            System.out.println("title = " + a.getTitle());
            System.out.println("content = " + a.getContent());
        }
    }
}