5. Querying

Session session = sessionFactory.openSession();

...

FullTextSession fullTextSession =Search.getFullTextSession(session);

SearchFactory searchFactory = fullTextSession.getSearchFactory();
org.apache.lucene.queryParser.QueryParser parser = 
    new QueryParser("title", searchFactory.getAnalyzer(Myth.class) );
try {
    org.apache.lucene.search.Query luceneQuery = parser.parse( "history:storm^3" );
}
catch (ParseException e) {
    //handle parsing failure
}

org.hibernate.Query fullTextQuery = fullTextSession.createFullTextQuery(luceneQuery);List result = fullTextQuery.list();//return a list of managed objects    

Note

Hibernate query方法是基於lucene query的:org.hibernate.Query, 這意味著Hibernate query也支持HQL, Native or Criteria). The regular list() , uniqueResult(), iterate() and scroll()等平常我們使用的方法

EntityManager em = entityManagerFactory.createEntityManager();

FullTextEntityManager fullTextEntityManager = org.hibernate.search.jpa.Search.getFullTextEntityManager(em);

...finalQueryBuilder b = fullTextEntityManager.getSearchFactory().buildQueryBuilder().forEntity(Myth.class).get();

org.apache.lucene.search.Query luceneQuery =  b.keyword().onField("history").boostedTo(3).matching("storm").createQuery();
javax.persistence.Query fullTextQuery = fullTextEntityManager.createFullTextQuery( luceneQuery );

List result = fullTextQuery.getResultList();//return a list of managed objects  

Note

接下來的例子都是介紹hibernate apis,但是可以很方便的轉換到jpa方式、

Note

使用lucene必須將日期轉化為String類型。而hibernate search不用

Note

如果不想使用橋(field bridge)或者分析器，可以使用ignoreAnalyzer()和ignoreFieldBridge（）

?     boostedTo：可以用在查詢實體或字段中，使用給定的因子提升整個查詢或特定字段。

?     withConstantScore (on query)：和boost（作用）一樣，所有匹配的查詢結果有一個常量分數。

?     filteredBy(on query)：使用過濾器過濾查詢結果。

?     ignoreAnalyzer (on field)：處理字段時忽略analyzer。

?     ignoreFieldBridge (on field)：處理字段時忽略field bridge。

Example 5.4. Wrapping a Lucene query into a Hibernate Query

FullTextSession fullTextSession = Search.getFullTextSession( session );

org.hibernate.Query fullTextQuery = fullTextSession.createFullTextQuery( luceneQuery );

fullTextQuery = fullTextSession    .createFullTextQuery( luceneQuery, Customer.class );

// or

fullTextQuery = fullTextSession    .createFullTextQuery( luceneQuery, Item.class, Actor.class );

org.hibernate.Query fullTextQuery =     fullTextSession.createFullTextQuery( luceneQuery, Customer.class );

fullTextQuery.setFirstResult(15); //start from the 15th 

elementfullTextQuery.setMaxResults(10); //return 10 elements

Tip

可以使用fulltextQuery.getResultSize()獲取全部匹配元素的個數。

org.hibernate.search.FullTextQuery query = s.createFullTextQuery( query, Book.class );

org.apache.lucene.search.Sort sort = new Sort(new SortField("title", SortField.STRING));
query.setSort(sort);
List results = query.list();

5.1.3.4. Fetching strategy 抓取策略

Criteria criteria =     s.createCriteria( Book.class ).setFetchMode( "authors", FetchMode.JOIN );

s.createFullTextQuery( luceneQuery ).setCriteriaQuery( criteria );

Important

隻有設置fetch mode才可以使用criteria的restriction

Important

如果返回多個不同類型實體，則不能使用setCriteriaQuery 

org.hibernate.search.FullTextQuery query =     s.createFullTextQuery( luceneQuery, Book.class );

query.setProjection( "id", "summary", "body", "mainAuthor.name" );

List results = query.list();

Object[] firstResult = (Object[]) results.get(0);

Integer id = firstResult[0];

String summary = firstResult[1];

String body = firstResult[2];

String authorName = firstResult[3];

FullTextQuery query = session.createFullTextQuery(luceneQuery, User.class);query.initializeObjectWith(    ObjectLookupMethod.SECOND_LEVEL_CACHE,    DatabaseRetrievalMethod.QUERY);

• ObjectLookupMethod.PERSISTENCE_CONTEXT: useful if most of the matching entities are already in the persistence context (ie loaded in the Session or EntityManager)

• ObjectLookupMethod.SECOND_LEVEL_CACHE: check first the persistence context and then the second-level cache.

5.2.2. Result size 返回結果數量

org.hibernate.search.FullTextQuery query =     s.createFullTextQuery( luceneQuery, Book.class );

//return the number of matching books without loading a single one

assert 3245 == query.getResultSize(); 

org.hibernate.search.FullTextQuery query =     s.createFullTextQuery( luceneQuery, Book.class );

query.setMaxResult(10);List results = query.list();

//return the total number of matching books regardless of pagination

assert 3245 == query.getResultSize(); 

Note

就像Google,搜索結果數量隻是個大概，如果有索引還沒有被更新添加

org.hibernate.search.FullTextQuery query =     s.createFullTextQuery( luceneQuery, Book.class );

query.setProjection( "title", "mainAuthor.name" );
query.setResultTransformer( 
    new StaticAliasToBeanResultTransformer( 
        BookView.class, 
        "title", 
        "author" ) 
);
List<BookView> results = (List<BookView>) query.list();

for(BookView view : results) {    

log.info( "Book: " + view.getTitle() + ", " + view.getAuthor() );

}

Warning

Document ID 和 實體類的ID不是同一個東西

FullTextQuery ftQuery = s.createFullTextQuery( luceneQuery, Dvd.class )

        .setProjection(

              FullTextQuery.DOCUMENT_ID,

              FullTextQuery.EXPLANATION,

              FullTextQuery.THIS );

@SuppressWarnings("unchecked") List<Object[]> results = ftQuery.list();

for (Object[] result : results) {

    Explanation e = (Explanation) result[1];

    display( e.toString() );

}

Example 5.19. Enabling fulltext filters for a given query

fullTextQuery = s.createFullTextQuery( query, Driver.class );

fullTextQuery.enableFullTextFilter("bestDriver");

fullTextQuery.enableFullTextFilter("security").setParameter( "login", "andre" );

fullTextQuery.list(); //returns only best drivers where andre has credentials

@Entity
@Indexed
@FullTextFilterDefs( {
    @FullTextFilterDef(name = "bestDriver", impl = BestDriversFilter.class), 
    @FullTextFilterDef(name = "security", impl = SecurityFilterFactory.class) 
})
public class Driver { ... }

public class BestDriversFilter extends org.apache.lucene.search.Filter {

    public DocIdSet getDocIdSet(IndexReader reader) throws IOException {

        OpenBitSet bitSet = new OpenBitSet( reader.maxDoc() );

        TermDocs termDocs = reader.termDocs( new Term( "score", "5" ) );

        while ( termDocs.next() ) {

            bitSet.set( termDocs.doc() );        }        return bitSet;    }}