Lucene in Action
Otis Gospodnetic Erik Hatcher
Understanding Lucene
Different people are fighting the same problem—information overload—using different approaches. Some have been working on novel user interfaces, some on intelligent agents, and others on developing sophisticated search tools like Lucene. Before we jump into action with code samples later in this chapter, we’ll give you a high-level picture of what Lucene is, what it is not, and how it came to be.
What Lucene is
Lucene is a high performance, scalable Information Retrieval (IR) library. It lets you add indexing and searching capabilities to your applications. Lucene is a mature, free, open-source project implemented in Java; it’s a member of the popular Apache Jakarta family of projects, licensed under the liberal Apache Software License. As such, Lucene is currently, and has been for a few years, the most popular free Java IR library.
As you’ll soon discover, Lucene provides a simple yet powerful core API that requires minimal understanding of full-text indexing and searching. You need to learn about only a handful of its classes in order to start integrating Lucene into an application. Because Lucene is a Java library, it doesn’t make assumptions about what it indexes and searches, which gives it an advantage over a number of other search applications.
People new to Lucene often mistake it for a ready-to-use application like a file-search program, a web crawler, or a web site search engine. That isn’t what Lucene is: Lucene is a software library, a toolkit if you will, not a full-featured search application. It concerns itself with text indexing and searching, and it does those things very well. Lucene lets your application deal with business rules specific to its problem domain while hiding the complexity of indexing and searching implementation behind a simple-to-use API. You can think of Lucene as a layer that applications sit on top of, as depicted in figure 1.5.
A number of full-featured search applications have been built on top of Lucene. If you’re looking for something prebuilt or a framework for crawling, document handling, and searching, consult the Lucene Wiki “powered by” page (http://wiki.apache.org/jakarta-lucene/PoweredBy) for many options: Zilverline, SearchBlox, Nutch, LARM, and jSearch, to name a few. Case studies of both Nutch and SearchBlox are included in chapter 10.
What Lucene can do for you
Lucene allows you to add indexing and searching capabilities to your applications (these functions are described in section 1.3). Lucene can index and make searchable any data that can be converted to a textual format. As you can see in figure 1.5.
圖Figure 1.5 A typical application integration with Lucene
外文原文翻譯
對Lucene的理解
人們用不同的方式討論著同壹個問題——信息超載。其中壹些致力與新型用戶界面的研究，另壹些是才智過人的代理，還有些則研究搜索工具，正如Lucene在我們對下壹章的樣本代碼操作之前，我們將向您詳細描述什麽是Lucene而什麽不是，以及怎樣來做它。
Lucene是什麽
Lucene是壹種高性能，可擴展的信息檢索（ IR ）的資料庫。它有添加的應用程序進行索引和搜索能力。 Lucene是壹款基於Java語言成熟的，免費開放源代碼的項目;它屬於流行的Apache Jakarta項目下的壹個分支並已領取牌照的自由Apache軟件許可證。因此， Lucene目前已成為幾年最熱門的免費Java軟件檢索。
您很快就會發現，Lucene提供了壹個既簡單又強大的核心的API代碼需要對全文索引和搜索能力的認識。您需要了解少數以開始整合成為壹個Lucene的應用。由於Lucene的是壹個Java的資料庫，它沒有對作出有關的假設索引和搜尋賦予它的優勢，超過了壹些其他的搜索應用程序。
新接觸的Lucene的往往是錯誤的，它為隨時可以使用的應用就像壹個文件搜索程序，網頁檢索器，或壹個網站的搜索引擎。這不是真正的Lucene： Lucene是壹個軟件庫，壹個工具包，但它並不是壹個功能齊全的搜索應用軟件。它是與全文索引和搜索相關。 Lucene讓您的應用程序處理業務規則，與相關領域有關，而隱藏在復雜的索引和搜索執行的背後是簡單易用的API 。妳可以把Lucene作為壹個描寫成1.5設置在頂層的軟件層。
壹批功能齊全的搜索應用程序，已高在Lucene之壹。如果您在尋找壹些編譯好的核心套件或壹個框架，用於抓尋找文件處理，搜索，諮詢Lucene的Wiki上的“動力”網頁（ http://wiki.apache.org/jakarta-lucene/poweredby ）對於許多選項： zilverline ， searchblox ， nutch ， larm ， jsearch ，僅舉幾例。案例研究雙方的nutch和searchblox是包括在第10章。
Lucene能為您做什麽
Lucene可以讓妳把索引和搜索功能添加到您的應用程序（這些職能是描述在第1.3 ） 。 Lucene可以編制索引和搜索作出可以轉換為文本格式的任何數據。妳可以看到在圖1.5 。