java - 如何使用 Lucene 将 LowerCase 应用于字符串

Question

我开始使用 Apache Lucene 8.0。我想知道如何使用 Lucene 将我的 String text 变量转换为小写。我不太确定如何做到这一点，因为我找不到任何例子。我想要的是这样的:

public class DocumentLowercase {

private Analyzer analyzer; 

public Analyzer DocAnalysis(Document d) {

    analyzer = new StandardAnalyzer();
    String text = d.text();

    **Here convert String Text into lowercase**
    ** maybe using Lower Case Tokenizer? but how? **        

    return analyzer;


}
}

Answer 1

StandardAnalyzer 已将所有内容转换为小写!

在此处查看文档:http://lucene.apache.org/core/8_0_0/core/org/apache/lucene/analysis/standard/StandardAnalyzer.html

他们说:

Filters StandardTokenizer with LowerCaseFilter and StopFilter, using a configurable list of stop words.

您还可以在源代码中查看 StandardAnalyzer 包含哪些组件:

  @Override
  protected TokenStreamComponents createComponents(final String fieldName) {
    final StandardTokenizer src = new StandardTokenizer();
    src.setMaxTokenLength(maxTokenLength);
    TokenStream tok = new LowerCaseFilter(src);
    tok = new StopFilter(tok, stopwords);
    return new TokenStreamComponents(r -> {
      src.setMaxTokenLength(StandardAnalyzer.this.maxTokenLength);
      src.setReader(r);
    }, tok);
  }

如果您想自定义分析器，您应该查看CustomAnalyzer。