我正在尝试编写用于字段类型的简单Solr lemmatizer,但是我似乎找不到有关编写TokenFilter的任何信息,因此我有点迷失了.这是我到目前为止的代码.

import java.io.IOException;
import java.util.List;
import org.apache.lucene.analysis.TokenFilter;
import org.apache.lucene.analysis.TokenStream;
import org.apache.lucene.analysis.tokenattributes.CharTermAttribute;
import org.apache.lucene.analysis.tokenattributes.PositionIncrementAttribute;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

class FooFilter extends TokenFilter {

    private static final Logger log = LoggerFactory.getLogger(FooFilter.class);
    private final CharTermAttribute termAtt = addAttribute(CharTermAttribute.class);
    private final PositionIncrementAttribute posAtt = addAttribute(PositionIncrementAttribute.class);

    public FooFilter(TokenStream input) {
        super(input);
    }

    @Override
    public boolean incrementToken() throws IOException {
        if (!input.incrementToken()) {
            return false;
        }

        char termBuffer[] = termAtt.buffer();
        List<String> allForms = Lemmatize.getAllForms(new String(termBuffer));
        if (allForms.size() > 0) {
            for (String word : allForms) {
                // Now what?
            }
        }

        return true;
    }
}

解决方法:

接下来,您要用单词替换或附加当前令牌termAtt.

样本替换语义

termAtt.setEmpty();
termAtt.copyBuffer(word.toCharArray(), 0, word.length());

添加新令牌的示例语义

对于要添加的每个令牌,必须设置CharTermAttribute属性,并设置递增令牌例程以返回true.

private List<String> extraTokens = ...
public boolean incrementToken() { 
  if (input.incrementToken()){ 
    // ... 
    return true; 
  } else if (!extraTokens.isEmtpy()) { 
    // set the added token and return true
    termAtt.setTerm(extraTokens.remove(0)); 
    return true; 
  } 
  return false; 
}