Compass全文检索系列之一：Compass入门

   Compass框架的参考文档,Compass是在Lucene的基础上做了封装，支持索引事务控制和增量索引，同时也能够和主流的SSH框架完美地整合在一起,操作Compass类似于操作Hibernate，它们的类/方法等设计的非常相似。下面我们通过一个实例来看看Compass到底是怎样来索引数据库，操作索引库和实现搜索功能的。
    步骤一：下载Compass，目前最新版本是2.2.0，可以到 http://www.compass-project.org/上下载。
    步骤二：在Eclipse中新建一个Java Project，解压compass-2.2.0-with-dependencies.zip，将dist目录下的compass-2.2.0.jar，commons-logging.jar和dist/lucene目录下的lucene-analyzers.jar，lucene-core.jar，lucene-highlighter.jar拷贝在工程的构建路径下，如下图所示：

    步骤三：新建一个Book（书籍）类，这个类就是我们要搜索的对象，其完整代码如下：

import org.compass.annotations.Index;
import org.compass.annotations.Searchable;
import org.compass.annotations.SearchableId;
import org.compass.annotations.SearchableProperty;
import org.compass.annotations.Store;

@Searchable
public class Book {
	private String id;//编号
	private String title;//标题
	private String author;//作者
	private float price;//价格

	public Book() {
	}

	public Book(String id, String title, String author, float price) {
		super();
		this.id = id;
		this.title = title;
		this.author = author;
		this.price = price;
	}

	@SearchableId
	public String getId() {
		return id;
	}

	@SearchableProperty(boost = 2.0F, index = Index.TOKENIZED, store = Store.YES)
	public String getTitle() {
		return title;
	}

	@SearchableProperty(index = Index.TOKENIZED, store = Store.YES)
	public String getAuthor() {
		return author;
	}

	@SearchableProperty(index = Index.NO, store = Store.YES)
	public float getPrice() {
		return price;
	}

	public void setId(String id) {
		this.id = id;
	}

	public void setTitle(String title) {
		this.title = title;
	}

	public void setAuthor(String author) {
		this.author = author;
	}

	public void setPrice(float price) {
		this.price = price;
	}

	@Override
	public String toString() {
		return "[" + id + "] " + title + " - " + author + " $ " + price;
	}

}

    这里有几个要注意的地方：@Searchable表示该类的对象是可被搜索的；@SearchableId表示索引建立的id；@SearchableProperty表示此字段可以被索引、被检索；对于Index，Store在这里就不作介绍了，不熟悉的朋友可以去看看Lucene API。
    步骤四：新建一个Searcher类，该类封装了对索引库的一些操作，包括新建索引，删除索引，重建索引，搜索等等。完整代码如下：

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

import org.compass.annotations.config.CompassAnnotationsConfiguration;
import org.compass.core.Compass;
import org.compass.core.CompassHits;
import org.compass.core.CompassSession;
import org.compass.core.CompassTransaction;

public class Searcher
{
	protected Compass compass;

	public Searcher()
	{
	}

	/**
	 * 初始化Compass
	 * @param path
	 */
	public Searcher(String path)
	{
		compass = new CompassAnnotationsConfiguration().setConnection(path).addClass(Book.class).setSetting("compass.engine.highlighter.default.formatter.simple.pre", "<font color='red'>").setSetting(
				"compass.engine.highlighter.default.formatter.simple.post", "</font>").buildCompass();
		Runtime.getRuntime().addShutdownHook(new Thread()
		{
			public void run()
			{
				compass.close();
			}
		});

	}

	/**
	 * 新建索引
	 * @param book
	 */
	public void index(Book book)
	{
		CompassSession session = null;
		CompassTransaction tx = null;
		try
		{
			session = compass.openSession();
			tx = session.beginTransaction();
			session.create(book);
			tx.commit();
		} catch (RuntimeException e)
		{
			if(tx!=null)
				tx.rollback();
			throw e;
		} finally
		{
			if (session != null)
			{
				session.close();
			}
		}
	}

	/**
	 * 删除索引
	 * @param book
	 */
	public void unIndex(Book book)
	{
		CompassSession session = null;
		CompassTransaction tx = null;
		try
		{
			session = compass.openSession();
			tx = session.beginTransaction();
			session.delete(book);
			tx.commit();
		} catch (RuntimeException e)
		{
			tx.rollback();
			throw e;
		} finally
		{
			if (session != null)
			{
				session.close();
			}
		}
	}

	/**
	 * 重建索引
	 * @param book
	 */
	public void reIndex(Book book)
	{
		unIndex(book);
		index(book);
	}

	/**
	 * 搜索
	 * @param queryString
	 * @return
	 */
	public List<Book> search(String queryString)
	{
		CompassSession session = null;
		CompassTransaction tx = null;
		try
		{
			session = compass.openSession();
			tx = session.beginTransaction();
			CompassHits hits = session.find(queryString);
			int n = hits.length();
			if (0 == n)
			{
				return Collections.emptyList();
			}
			List<Book> books = new ArrayList<Book>();
			for (int i = 0; i < n; i++)
			{
				books.add((Book) hits.data(i));
			}
			hits.close();
			tx.commit();
			return books;
		} catch (RuntimeException e)
		{
			tx.rollback();
			throw e;
		} finally
		{
			if (session != null)
			{
				session.close();
			}
		}
	}
}

    步骤五：新建一个测试类进行测试.完整源码如下：

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.List;
import java.util.UUID;

public class Main
{
	static List<Book> db = new ArrayList<Book>();
	static Searcher searcher = new Searcher("E:/index");

	public static void main(String[] args)
	{
		add(new Book(UUID.randomUUID().toString(), "Thinking in Java", "Bruce", 109.0f));
		add(new Book(UUID.randomUUID().toString(), "Effective Java", "Joshua", 12.4f));
		add(new Book(UUID.randomUUID().toString(), "Java Thread Programing", "Paul", 25.8f));
		int n;
		do
		{
			n = displaySelection();
			switch (n)
			{
			case 1:
				listBooks();
				break;
			case 2:
				addBook();
				break;
			case 3:
				deleteBook();
				break;
			case 4:
				searchBook();
				break;
			case 5:
				return;
			}
		} while (n != 0);
	}

	static int displaySelection()
	{
		System.out.println("\n==select==");
		System.out.println("1. List all books");
		System.out.println("2. Add book");
		System.out.println("3. Delete book");
		System.out.println("4. Search book");
		System.out.println("5. Exit");
		int n = readKey();
		if (n >= 1 && n <= 5)
			return n;
		return 0;
	}

	/**
	 * 增加一本书到数据库和索引中
	 * @param book
	 */
	private static void add(Book book)
	{
		db.add(book);
		searcher.index(book);
	}

	/**
	 * 打印出数据库中的所有书籍列表
	 */
	public static void listBooks()
	{
		System.out.println("==Database==");
		int n =1;
		for (Book book :db)
		{
			System.out.println(n+")"+book);
			n++;
		}
	}

	/**
	 * 根据用户录入，增加一本书到数据库和索引中
	 */
	public static void addBook()
	{
		String title = readLine(" Title: ");
		String author = readLine(" Author: ");
		String price = readLine(" Price: ");
		Book book = new Book(UUID.randomUUID().toString(),title,author,Float.valueOf(price));
		add(book);
	}

	/**
	 * 删除一本书，同时删除数据库，索引库中的
	 */
	public static void deleteBook()
	{
		listBooks();
		System.out.println("Book index: ");
		int n = readKey();
		Book book = db.remove(n-1);
		searcher.unIndex(book);
	}

	/**
	 * 根据输入的关键字搜索书籍
	 */
	public static void searchBook()
	{
		String queryString = readLine(" Enter keyword: ");
		List<Book> books = searcher.search(queryString);
		System.out.println(" ====search results:"+books.size()+"====");
		for (Book book :books)
		{
			System.out.println(book);
		}
	}

	public static int readKey()
	{
		BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
		try
		{
			int n = reader.read();
			n=Integer.parseInt(Character.toString((char)n));
			return n;
		}catch(Exception e)
		{
			throw new RuntimeException();
		}
	}
	
	public static String readLine(String propt)
	{
		System.out.println(propt);
		BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
		try{
			return reader.readLine();
		}catch(Exception e)
		{
			throw new RuntimeException();
		}
	}
}

    该工程整个文件结构如下图所示：



    运行结果：




    项目源码：如下