Lucene分词报错：”TokenStream contract violation: close() call missing”

public Set<String> slicing(String text){
    Set<String> result = new HashSet<>();
    StringReader reader = null;
    TokenStream tokenStream = null;
    try {
        reader = new StringReader(text);
        tokenStream = analyzer.tokenStream("", reader);  
        CharTermAttribute charTermAttribute  = tokenStream.getAttribute(CharTermAttribute.class); 
        OffsetAttribute offsetAttribute = tokenStream.addAttribute(OffsetAttribute.class);  
        tokenStream.reset();
            while (tokenStream.incrementToken()) {  
                int startOffset = offsetAttribute.startOffset();  
                int endOffset   = offsetAttribute.endOffset();
                if((endOffset - startOffset) > 1){
                    String term = charTermAttribute.toString(); 
                    result.add(term);
                }
            }  
    } catch (IOException e) {
        e.printStackTrace();
    } finally{
        IOs.close(tokenStream, reader);
    }
    return result;
}