Compass是基于Lucene 的更高层的抽象,假如你正打算做关于搜索方面的模块的话,那我建议你使用Compass,他提供了可配置方案,而且比Lucene更加容易使用。如果你的 系统中使用Spring, Hibernate,JDO, IBatis。。。 Compass是最好的选择,他能够非常方便的集成到现有系统中去。 1. Compass的framework的系统结构。 感觉Compass的代码的结构简直就是剽窃Hibernate的,可能Compass的最初目的是用来整合Hibernate的, CompassConfiguration conf = new CompassConfiguration().configure().addClass(Author.class); Compass compass = conf.buildCompass(); CompassSession session = compass.openSession(); CompassTransaction tx = null; try { tx = session.beginTransaction(); ... session.save(author); CompassHits hits = session.find("jack london"); Author a = (Author) hits.data(0); Resource r = hits.getResource(0); ... tx.commit(); } catch (CompassException ce) { if (tx != null) tx.rollback(); } finally { session.close(); } 假如你对Hibernate有了解的话,相信你对Compass会比较容易理解的,你可以把Hibernate的思想转移到Compass上。现在让我们看看他们之间的相似吧。 compass.cfg.xml <compass-core-config xmlns="http://www./compass/schema/core-config" xmlns:xsi="http://www./2001/XMLSchema-instance" xsi:schemaLocation="http://www./compass/schema/core-config http://www./compass/schema/compass-core-config.xsd"> <compass name="default"> <connection> <file path="target/test-index"/> </connection> <mappings> <class name="test.Author" /> </mappings> </compass> </compass-core-config> 这个是Compass总的配置文件,其中定义了索引文件存储的位置(这里是用文件系统,Compass有多种选择,你也可以选数据库或其他),Compass索引的对象是面向PoJo的,这里的是Author,对应的文件是test/Author.cpm.xml. 当然这里面的配置属性不止这么多,更多的属性见Configure属性。 CompassConfiguration conf = new CompassConfiguration() .setSetting(CompassEnvironment.CONNECTION, "my/index/dir") .addResource(DublinCore.cmd.xml).addClass(Author.class); Compass compass = conf.buildCompass(); 这 里我们CompassConfiguration会读取默认的在classpath中的compass.cfg.xml初始化,然后得到Compass对 象,可能你会马上意思到这个Compass肯定对应于Hibenate中的SessionFactory,是的,这是一个重量级的对象, 我们需要 通过这个对象得到CompassSession,然后进行CRUD操作,CompassSession跟Hibernate中的Session一样是个 lightweight对象。关于对Search domain的配置(Author.cpm.xml),大家可以查看cpm文件配置。在那里面 主要是定义了那些properties是需要被索引的。 <?xml version="1.0"?> <compass-core-mapping package="eg"> <class name="Author" alias="author"> <id name="id" /> <constant> <meta-data>type</meta-data> <meta-data-value>person</meta-data-value> <meta-data-value>author</meta-data-value> </constant> <property name="name"> <meta-data>name</meta-data> <meta-data>authorName</meta-data> </property> <property name="birthday"> <meta-data>birthday</meta-data> </property> <component name="books" ref-alias="book" /> <!-- can be a reference instead of component <reference name="books" ref-alias="book" /> --> </class> <class name="Book" alias="book"> ... </class> </compass-core-mapping> 2. 索引文件结构 ---[index dir]/index | |-- [subIndex1] | | | |--- segments | |--- [segment1] | |--- [segment2] | |-- [subIndex2] | | | |--- segments | |--- [segment1] | |--- [segment2] | |--- [segment3] | ... 基本上是一个search domain放到一个subIndex文件夹中,更确切的说是相同alias name的search domain放到相同的sub index folder中。 3. Compass中的操作 通 过CompassSession我们可以进行save,delete, get,load。假如我们有两个domain Object,Author 和 Book,假如我们想要query Book的话要怎样做呢? 我们需要使用alias(这个属性定义在cmp文件中), 通过CompassQueryBuilder去构造CompassQuery, CompassQueryBuilder非常灵活,非常像Hibernate的Criteria查询。具体的sample请看 Working with objects CompassHits hits = session.createQueryBuilder() .queryString("+name:jack +familyName:london") .setAnalyzer("an1") // use a different analyzer .toQuery() .addSort("familyName", CompassQuery.SortPropertyType.STRING) .addSort("birthdate", CompassQuery.SortPropertyType.INT) .hits(); 4. CompassGps and CompassGpsDevice CompassGps 像是一个Service,他需要在application startup时启动服务, application shutdown停止服务,CompassGpsDevice不能独立的存在,他需要依赖CompassGps, CompassGps为CompassGpsDevice提供 Compass对象,他们一起为程序提供Index的实时更新。 Compass整合Hibernate 等等 persitance framework的代码就在CompassGpsDevice里,你需要提供不同的Device,如HibernateDevice, JDODevice。你也 可以实现自己的Device, CompassGpsDevice会把domain object的更新事件通过CompassGps去通知Compass去更新索引文件,这样就是可以实时更新index了。有兴趣的话可以看看Hibernate3GpsDevice的 registerEventsForHibernate31()方法,他给Hibernate的save,delete,update操作增加listener。当然我们可以使用aop自己去实现这块。CompassGps and CompassGpsDevice Compass compass = ... // configure compass CompassGps gps = new SingleCompassGps(compass); CompassGpsDevice device1 = ... // configure the first device device1.setName("device1"); gps.addDevice(device1); CompassGpsDevice device2 = ... // configure the second device device2.setName("device2"); gps.addDevice(device2); gps.start(); .... .... //on application shutdown gps.stop(); 5. 整合Spring,Hibenate 在Compass 的lib里面就有非常好的一个sample了(petclinic),里面有对Spring,Hibenate的整合,其实对spring来说也就是通过 ioc把CompassGps 和 Compass定义好。CompassGps主要负责re-index和index实时更新 , Compass主要提供了自定义Search部分的入口(CompassTemplate)。Spring提供了对Compass的DAO的整合,在 CompassDaoSupport 中拿到CompassTemplate,这个跟spring对hibernatedao的支持是一致的。 public class LibraryCompassDao extends CompassDaoSupport { public int getNumberOfHits(final String query) { Integer numberOfHits = (Integer)getCompassTemplate().execute( new CompassCallback() { public Object doInCompass(CompassSession session) { CompassHits hits = session.find(query); return new Integer(hits.getLength()); } } ); } return numberOfHits.intValue(); } <beans> <bean id="libraryCompass" class="LibraryCompassDao"> <property name="compass"> <ref local="compass" /> </property> </bean> </beans> <!-- COMPASS START --> <bean id="compass" class="org.compass.spring.LocalCompassBean"> <property name="resourceLocations"> <list> <value>classpath:org/compass/sample/petclinic/petclinic.cmd.xml</value> <value>classpath:petclinic.cpm.xml</value> </list> </property> <property name="compassSettings"> <props> <prop key="compass.engine.connection">file://${user.home}/compass/petclinic</prop> <prop key="compass.transaction.factory">org.compass.spring.transaction.SpringSyncTransactionFactory</prop> </props> </property> <property name="transactionManager"> <ref local="transactionManager" /> </property> </bean> <bean id="hibernateGpsDevice" class="org.compass.spring.device.hibernate.SpringHibernate3GpsDevice"> <property name="name"><value>hibernateDevice</value></property> <property name="sessionFactory"><ref local="sessionFactory" /></property> </bean> <bean id="compassGps" class="org.compass.gps.impl.SingleCompassGps" init-method="start" destroy-method="stop"> <property name="compass"><ref bean="compass" /></property> <property name="gpsDevices"> <list> <ref local="hibernateGpsDevice" /> </list> </property> </bean> <!-- COMPASS END --> <!-- Transaction manager for a single Hibernate SessionFactory (alternative to JTA) --> <bean id="transactionManager" class="org.springframework.orm.hibernate3.HibernateTransactionManager"> <property name="sessionFactory"><ref local="sessionFactory"/></property> </bean> <!----------------------------一下是对anototion的配置。--> <bean id="annotationConfiguration" class="org.compass.annotations.config.CompassAnnotationsConfiguration"> </bean> <!-- 核心Compass Bean,search及index时使用 --> <bean id="compass" class="org.compass.spring.LocalCompassBean"> <!-- anontaition式设置 --> <property name="classMappings"> <list> <value>com.dengyin.compass.sample.domain.Book</value> </list> </property> <property name="compassConfiguration" ref="annotationConfiguration"/> <!-- xml 文件式设置 <property name="resourceLocations"> <list> <value>classpath:compass-springside.cmd.xml</value> <value>classpath:compass-springside.cpm.xml</value> </list> </property> --> <property name="compassSettings"> <props> <prop key="compass.engine.connection"> file://${user.home}/springside/compass </prop> <prop key="compass.transaction.factory"> org.compass.spring.transaction.SpringSyncTransactionFactory </prop> </props> </property> <property name="transactionManager" ref="transactionManager"/> </bean> <!--Compass的GPS绑定,在index时使用--> <bean id="compassGps" class="org.compass.gps.impl.SingleCompassGps" init-method="start" destroy-method="stop"> <property name="compass" ref="compass"/> <property name="gpsDevices"> <list> <bean class="org.compass.spring.device.hibernate.SpringHibernate3GpsDevice"> <property name="name"> <value>hibernateDevice</value> </property> <property name="sessionFactory" ref="sessionFactory"/> </bean> </list> </property> </bean> ok! 相信你对Compass有一定的了解了。 thanks Compass: http://www./compass/ Compass文档:http://www./compass/content/documentation.html |
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