Hibernate Memcached 配置

最新推荐文章于 2021-12-28 11:51:35 发布

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本文介绍如何将Memcached作为二级缓存集成到Hibernate中，包括所需依赖、配置步骤及示例代码。

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官方网址: http://code.google.com/p/hibernate-memcached/
目前最新版本为1.0, 支持Hibernate3.3.

下面是具体的使用方法:
hibernate-memcached需要支持的类库如下:

hibernate-memcached-<version>.jar
memcached-2.1.jar
spy-2.4.jar
commons-codec 1.3
slf4j-1.5.0.jar 如果你的项目使用的是Log4j,可以用 slf4j-log4j12-1.5.0.jar

配置方法如下：

配置Hibernate使用cache提供类

hibernate.cache.provider_class

com.googlecode.hibernate.memcached.MemcachedCacheProvider

设置查询缓存开启

hibernate.cache.use_query_cache

true

其它一些参数设置说明:

Property	Default	Description
hibernate.memcached.servers	localhost:11211	memcached 服务地址，多个用空格分隔格式host:port
hibernate.memcached.cacheTimeSeconds	300	缓存失效时间,单位秒
hibernate.memcached.keyStrategy	HashCodeKeyStrategy	缓存Key生成存储HashCode算法
hibernate.memcached.readBufferSize	DefaultConnectionFactory.DEFAULT_READ_BUFFER_SIZE	从服务器读取数据缓存区大小
hibernate.memcached.operationQueueLength	DefaultConnectionFactory.DEFAULT_OP_QUEUE_LEN	Maximum length of the operation queue returned by this connection factory
hibernate.memcached.operationTimeout	DefaultConnectionFactory.DEFAULT_OPERATION_TIMEOUT	操作超时时间设置
hibernate.memcached.hashAlgorithm	HashAlgorithm.KETAMA_HASH	新增缓存数据到服务器时使用的Hash散列算法。当 hibernate-memcached 设置成 KETAMA_HASH算法时,注意:默认客户端API使用的是 HashAlgorithm.NATIVE_HASH
hibernate.memcached.clearSupported	false	支持MemcachedCache.clear()方法清空缓存。建议不要开启。

配置示例(本文以Hibernate3.3-entitymanager为例)
配置 persistence.xml文件

<? xml version="1.0" encoding="UTF-8" ?>
< persistence xmlns ="http://java.sun.com/xml/ns/persistence" " target ="_new" > http://java.sun.com/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_1_0.xsd" version="1.0">

< persistence-unit name ="entityManager" transaction-type ="RESOURCE_LOCAL" >
< provider > org.hibernate.ejb.HibernatePersistence </ provider >
< jta-data-source > java:comp/env/jdbc/qualitydb </ jta-data-source >

< properties >
< property name ="hibernate.dialect" value ="org.hibernate.dialect.PostgreSQLDialect" />
< property name ="hibernate.max_fetch_depth" value ="3" />
< property name ="hibernate.show_sql" value ="true" />

< property name ="hibernate.cache.region_prefix" value ="quality.cache.ehcache" />
< property name ="hibernate.cache.use_second_level_cache" value ="true" />
< property name ="hibernate.cache.use_structured_entries" value ="true" />
< property name ="hibernate.cache.use_query_cache" value ="true" />
< property name ="hibernate.cache.provider_class" value ="com.googlecode.hibernate.memcached.MemcachedCacheProvider" />
< property name ="hibernate.memcached.servers" value ="localhost:11211" />

</ properties >

</ persistence-unit >

</ persistence >

启动后，提示如下：
2008-08-28 17:10:08,312 JCLLoggerAdapter.java265 INFO -- Starting MemcachedClient...
2008-08-28 17:10:08.718 INFO net.spy.memcached.MemcachedConnection: Added {QA sa=localhost/127.0.0.1:11211, #Rops=0, #Wops=0, #iq=0, topRop=null, topWop=null, toWrite=0, interested=0} to connect queue
2008-08-28 17:10:08.750 INFO net.spy.memcached.MemcachedConnection: Connection state changed for sun.nio.ch.SelectionKeyImpl@16e59da

表示我们第一步配置已经成功了，接下来，对需要进行缓存的Entity进行配置

1 @Entity
2 @Cache(usage = CacheConcurrencyStrategy.READ_WRITE) // 设置要求缓存
3 public class Student {
4
5    @Id
6    @Column(length = 32 )
7      private String id;
8
9      @Column(length = 20 )
10      private string name;
11
12      @OneToMany
13      @Cache(usage = CacheConcurrencyStrategy.READ_WRITE)
14      private Set < Book > books;
15
16 }

Ok,现在配置已经完成。