java如何使用lucene索引查询国家代码？

Question

我正在为citynames和countrycodes创建一个lucene索引（取决于彼此）。我希望国家代码是小写搜索和精确匹配

首先，我现在尝试查询单个countrycode并查找与该代码匹配的所有索引元素。我的结果总是空的

//prepare
VERSION = Version.LUCENE_4_9;
IndexWriterConfig config = new IndexWriterConfig(VERSION, new SimpleAnalyzer());

//index
Document doc = new Document();
doc.add(new StringField("countryCode", countryCode, Field.Store.YES));
writer.addDocument(doc);

//lookup
Query query = new QueryParser(VERSION, "countryCode", new SimpleAnalyzer()).parse(countryCode);

结果: 当我查询诸如“IT”、“DE”、“EN”等coutrycode时，结果总是空的。为什么？ 对于两个字母的国家代码，SimpleAnalyzer是否来自

Answer 1

我有点困惑。我假设您的索引编写器是在代码中未提供的某些部分中初始化的，但是您不是将Version传递到SimpleAnalyzer吗？SimpleAnalyzer没有参数构造函数，从3开始就没有。十、 无论如何

这是我看到的唯一真正的问题。下面是一个使用您的代码的工作示例：

private static Version VERSION;

public static void main(String[] args) throws IOException, ParseException {
    //prepare
    VERSION = Version.LUCENE_4_9;
    Directory dir = new RAMDirectory();
    IndexWriterConfig config = new IndexWriterConfig(VERSION, new SimpleAnalyzer(VERSION));
    IndexWriter writer = new IndexWriter(dir, config);

    String countryCode = "DE";

    //index
    Document doc = new Document();
    doc.add(new TextField("countryCode", countryCode, Field.Store.YES));
    writer.addDocument(doc);
    writer.close();

    IndexSearcher search = new IndexSearcher(DirectoryReader.open(dir));
    //lookup
    Query query = new QueryParser(VERSION, "countryCode", new SimpleAnalyzer(VERSION)).parse(countryCode);

    TopDocs docs = search.search(query, 1);
    System.out.println(docs.totalHits);
}

Answer 2

对于StringField，可以使用TermQuery而不是QueryParser

Directory dir = new RAMDirectory();
IndexWriterConfig config = new IndexWriterConfig(Version.LUCENE_4_9, new SimpleAnalyzer(Version.LUCENE_4_9));
IndexWriter writer = new IndexWriter(dir, config);

String countryCode = "DE";

// index
Document doc = new Document();
doc.add(new StringField("countryCode", countryCode, Store.YES));
writer.addDocument(doc);
writer.close();

IndexSearcher search = new IndexSearcher(DirectoryReader.open(dir));
//lookup
Query query = new TermQuery(new Term("countryCode", countryCode));

TopDocs docs = search.search(query, 1);
System.out.println(docs.totalHits);