Lucene.NET和懶加載

Question

這是一個棘手的問題：我想通過Lucene搜索結果進行延遲加載。可能？

這裏是我的代碼：

public IEnumerable<BizObj> Search(string query) 
{ 
    var parsedQuery = new QueryParser(...).Parse(); 
    var searcher = new IndexSearcher(parsedQuery, storage); 
    try 
    { 
     var hits = searcher.Search(parsedQuery); 

     // Hooray for LINQ's lazy-evaluated Select method! 
     // But oh noes!! searcher will be closed by the time it 
     // gets executed, thus resulting in an exception. :-(
     return hits.Select(hit => PullBizObjectFromDatabase(hit)); 
    } 
    finally 
    { 
     searcher.Close(); 
    } 
} 

消費代碼：

var searchResults = from result in blah.Search("hello, world!") 
        where SomeBizLogic(result) 
        select result; 

// Print the top 50 search results. 
foreach (var result in searchResults.Take(50)) 
{ 
    // Exception! The searcher field inside Search(...) has been closed! :-(
    Console.WriteLine(result); 
} 

我的問題是，如何從Lucene的我懶加載搜索結果？

Answer 1

有幾個選項玩弄後，我已經想通了答案：使用yield返回迭代器：

public IEnumerable<BizObj> Search(string query) 
{ 
    var parsedQuery = new QueryParser(...).Parse(); 
    var searcher = new IndexSearcher(parsedQuery, storage); 
    try 
    { 
     var hits = searcher.Search(parsedQuery); 
     foreach (var hit in hits) 
     { 
     yield return PullBizObjectFromDatabase(hit); 
     } 
    } 
    finally 
    { 
     searcher.Close(); 
    } 
} 

隨着收益率的回報迭代器，搜索並沒有得到處置，直到消費者完成與他們的評價。輝煌！從Lucene延遲加載的搜索結果，正是我一直在尋找的。嗬！ :-)

Answer 2

查看HitCollector對象。 例如http://rosowski.wordpress.com/2008/07/29/lucene-using-the-hitcollector/