lucene中Field简介
Lucene 6.1.0中存在的field种类如下(后缀是Field):
下面介绍几个常用的Field类型:
TextField
A field that is indexed and tokenized, without term vectors. For example this would be used on a 'body' field, that contains the bulk of a document's text.
是一个会自动被索引和分词的字段。一般被用在文章的正文部分。
StringField
A field that is indexed but not tokenized: the entire String value is indexed as a single token. For example this might be used for a 'country' field or an 'id' field. If you also need to sort on this field, separately add a SortedDocValuesField to your document.
StringField会被索引,但是不会被分词,即会被当作一个完整的token处理,一般用在“国家”或者“ID”.
StoredField
A field whose value is stored so that IndexSearcher.doc(int) and IndexReader.document() will return the field and its value.
也就是一个默认会被存储的Field。
举个例子
(下面是对新闻数据进行索引的过程,数据存储在MySQL数据库中,title列存文章标题,content存正文,url存文章所在的链接,author是文章的作者):
Field field = null; if (rs.getString("title") != null) { field = new TextField("title", rs.getString("title"), Field.Store.YES); document.add(field); } if (rs.getString("content") != null) { field = new TextField("content", rs.getString("content"), Field.Store.NO); document.add(field); } if (rs.getString("url") != null) { field = new StringField("url", rs.getString("url"), Field.Store.YES); document.add(field); } if (rs.getString("author") != null) { field = new TextField("author", rs.getString("author"), Field.Store.YES); document.add(field); } writer.addDocument(document);
第一个参数是设置field的name,第二个是value,第三个是选择是否存储,如果存储的话在检索的时候可以返回值。
一般对于文章正文都不需要存储,在检索的时候只需要返回文章的标题和url即可。