今天在网上看到一个用Memcached作为Hibernate二级分布式缓存，感觉挺有兴趣，就是尝试用了，感觉还不错，就推荐给大家看一下。
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:
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。
Good Luck!
Yours Matthew!