如何使用Lucene查询ElasticSearch索引

Question

我可以使用Lucene查询ElasticSearch索引吗？

我使用ElasticSearch创建了一个索引，并插入了以下三个文档：

$ curl -XPOST localhost:9200/index1/type1 -d '{"f1":"dog"}'
$ curl -XPOST localhost:9200/index1/type2 -d '{"f2":"cat"}'
$ curl -XPOST localhost:9200/index1/type2 -d '{"f3":"horse"}'

import org.apache.lucene.analysis.standard.StandardAnalyzer;
import org.apache.lucene.document.Document;
import org.apache.lucene.index.DirectoryReader;
import org.apache.lucene.index.IndexReader;
import org.apache.lucene.queryparser.classic.QueryParser;
import org.apache.lucene.search.IndexSearcher;
import org.apache.lucene.search.Query;
import org.apache.lucene.search.ScoreDoc;
import org.apache.lucene.search.TopScoreDocCollector;
import org.apache.lucene.store.Directory;
import org.apache.lucene.store.FSDirectory;
import org.apache.lucene.util.Version;

import java.io.File;

public class TestES {

void doWork(String[] args) throws Exception {
    // Index reader for already created ElasticSearch index
    String indx1 = "/path-to-index/elasticsearch-0.90.0.RC2-SNAPSHOT/data/elasticsearch/nodes/0/indices/index1/1/index";
    Directory index = FSDirectory.open(new File(indx1));
    IndexReader reader = DirectoryReader.open(index);
    IndexSearcher searcher = new IndexSearcher(reader);

    // Looks like the query is correct since we do get a hit
    StandardAnalyzer analyzer = new StandardAnalyzer(Version.LUCENE_41);
    Query q = new QueryParser(Version.LUCENE_41, "f2", analyzer).parse("cat");
    TopScoreDocCollector collector = TopScoreDocCollector.create(10, true);
    searcher.search(q, collector);
    ScoreDoc[] hits = collector.topDocs().scoreDocs;

    // We do get a hit, but results always displayed as null except for "_uid"
    if (hits.length > 0) {
        int docId = hits[0].doc;
        Document d = searcher.doc(docId);
        System.out.println("DocID " + docId + ", _uid: " + d.get("_uid") );
        System.out.println("DocID " + docId + ", f2: " + d.get("f2") );
    }
    reader.close();
}

public static void main(String[] args) throws Exception {
  TestES hl = new TestES();
  hl.doWork(args);
}
}

Results:
DocID 0, _uid: type2#3K5QXeZhQnit9UXM9_4bng
DocID 0, f2: null

null

不幸的是，d.get(“_source”）也返回null。

如何检索匹配查询的文档字段？

谢谢你。

Answer 1

正如注释中所述，我需要以二进制值的形式检索字段“_source”。这样就成功了：d.getbinaryvalue（“_source”），它检索了[7b 22 66 32 22 3a 22 63 61 74 22 7d]，它是{“f2”：“cat”}。贾瓦娜，谢谢你的帮助。