问题:
在Web开发过程中,我们经常会需要对页面、对象、数据进行缓存,同时支持集群/分布式缓存。在javaEE中比较流行通过ehcache进行解决。学前参考:http://www.cnblogs.com/deepbreath/p/5456413.html
解决办法:
spring4.X+ehcache.X集群。代码如下:
pom.xml
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<parent>
<artifactId>testAll</artifactId>
<groupId>com.yada.test</groupId>
<version>1.0-SNAPSHOT</version>
</parent>
<modelVersion>4.0.0</modelVersion>
<artifactId>ehCacheDemo</artifactId>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<spring.version>4.2.3.RELEASE</spring.version>
</properties>
<dependencies>
<dependency>
<groupId>org.ehcache</groupId>
<artifactId>ehcache</artifactId>
<version>3.1.1</version>
</dependency>
<!-- spring begin-->
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-aop</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-beans</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-context</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-core</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-expression</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-tx</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-context-support</artifactId>
<version>${spring.version}</version>
</dependency>
<!--spring end-->
<!-- ehcache 相关jar包 **beging** -->
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-api</artifactId>
<version>1.7.10</version>
</dependency>
<dependency>
<groupId>com.googlecode.ehcache-spring-annotations</groupId>
<artifactId>ehcache-spring-annotations</artifactId>
<version>1.2.0</version>
</dependency>
<!--<dependency>-->
<!--<groupId>net.sf.ehcache</groupId>-->
<!--<artifactId>ehcache</artifactId>-->
<!--<version>2.10.2</version>-->
<!--<type>pom</type>-->
<!--</dependency>-->
</dependencies>
</project>
ehcache.xml
<?xml version="1.0" encoding="UTF-8"?>
<ehcache>
<defaultCache
maxElementsInMemory="10000"
eternal="false"
timeToIdleSeconds="120"
timeToLiveSeconds="120"
overflowToDisk="true"
maxElementsOnDisk="10000000"
diskPersistent="false"
diskExpiryThreadIntervalSeconds="120"
memoryStoreEvictionPolicy="LRU"
/>
<cache name="infoCache"
maxElementsInMemory="1000"
maxElementsOnDisk="1000"
overflowToDisk="false"
diskSpoolBufferSizeMB="20"
timeToIdleSeconds="180"
timeToLiveSeconds="180"
memoryStoreEvictionPolicy="LRU">
<cacheEventListenerFactory class="net.sf.ehcache.distribution.RMICacheReplicatorFactory"
properties="replicateAsynchronously=true, replicatePuts=true, replicateUpdates=true,replicateUpdatesViaCopy=false, replicateRemovals=true "/>
</cache>
<!-- rmi本地cache服务 -->
<cacheManagerPeerListenerFactory
class="net.sf.ehcache.distribution.RMICacheManagerPeerListenerFactory"
properties="hostName=localhost, port=40001, socketTimeoutMillis=2000"/>
<!-- rmi远程cache服务 -->
<cacheManagerPeerProviderFactory
class="net.sf.ehcache.distribution.RMICacheManagerPeerProviderFactory"
properties="peerDiscovery=manual, rmiUrls=
//22.7.16.98:40002/infoCache"/>
</ehcache>
applicationContext-ehcache.xml
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:cache="http://www.springframework.org/schema/cache"
xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/cache
http://www.springframework.org/schema/cache/spring-cache.xsd">
<cache:annotation-driven cache-manager="ehcacheManager"/>
<bean id="infoCache" class="com.test.ehcache.InfoCache">
<constructor-arg name="cacheManager" ref="ehcacheManager"/>
<constructor-arg name="cacheName" value="infoCache"/>
</bean>
<!-- cacheManager工厂类,指定ehcache.xml的位置 -->
<bean id="cacheManagerFactory" class="org.springframework.cache.ehcache.EhCacheManagerFactoryBean">
<property name="configLocation" value="classpath:/ehcache.xml"/>
</bean>
<!-- 声明cacheManager -->
<bean id="ehcacheManager" class="org.springframework.cache.ehcache.EhCacheCacheManager">
<property name="cacheManager" ref="cacheManagerFactory"/>
</bean>
</beans>
InfoCache.java
package com.test.ehcache;
import org.springframework.cache.Cache;
import org.springframework.cache.ehcache.EhCacheCacheManager;
/**
* Created by ** on 2016/9/5.
*/
public class InfoCache {
private EhCacheCacheManager cacheManager;
private String cacheName;
public InfoCache(EhCacheCacheManager cacheManager,String cacheName){
this.cacheManager =cacheManager ;
this.cacheName = cacheName ;
}
public String put(String infoKey, String doc) {
cacheManager.getCache(cacheName).put(infoKey, doc);
return doc;
}
public String get(String smsKey) {
Cache.ValueWrapper valueWrapper = cacheManager.getCache(cacheName).get(smsKey);
if(valueWrapper==null){
// System.out.println(valueWrapper.get());
return "no result" ;
}
return valueWrapper.get().toString();
}
public void remove(String smsKey) {
cacheManager.getCache(cacheName).evict(smsKey);
}
}
App.java
package com.test.ehcache;
import org.springframework.context.support.ClassPathXmlApplicationContext;
/**
* Created by ** on 2016/9/5.
*/
public class App {
public static void main(String[] args) {
try {
Thread.sleep(5000);
} catch (InterruptedException e) {
e.printStackTrace();
}
ClassPathXmlApplicationContext classPathXmlApplicationContext = new ClassPathXmlApplicationContext("applicationContext.xml");
System.out.println("start secceed!");
InfoCache infoCache =(InfoCache)classPathXmlApplicationContext.getBean("infoCache") ;
int num = 0 ;
while (true){
try {
Thread.sleep(1000);
num++;
System.out.println("Who are 2b ? "+infoCache.get("2b"));
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
}
节点二:App.java
import org.springframework.context.support.ClassPathXmlApplicationContext;
/**
* Created by ** on 2016/9/5.
*/
public class App {
public static void main(String[] args) {
ClassPathXmlApplicationContext classPathXmlApplicationContext = new ClassPathXmlApplicationContext("applicationContext.xml");
System.out.println("start secceed!");
InfoCache infoCache =(InfoCache)classPathXmlApplicationContext.getBean("infoCache") ;
int num = 0 ;
infoCache.put("2b","is bob !") ;
while (true){
try {
num++;
infoCache.remove("2b");
infoCache.put("2b","is bob !") ;
Thread.sleep(1000);
} catch (Exception e) {
e.printStackTrace();
}
}
}
}
节点三:App.app
public class App {
public static void main(String[] args) {
ClassPathXmlApplicationContext classPathXmlApplicationContext = new ClassPathXmlApplicationContext("applicationContext.xml");
System.out.println("start secceed!");
InfoCache infoCache =(InfoCache)classPathXmlApplicationContext.getBean("infoCache") ;
int num = 0 ;
while (true){
try {
Thread.sleep(1000);
num++;
System.out.println("Who are 2b ? "+infoCache.get("2b"));
} catch (Exception e) {
e.printStackTrace();
}
}
}
}
结果输出:
Who are 2b ? no result
Who are 2b ? is bob !
Who are 2b ? is bob !
Who are 2b ? is bob !
Who are 2b ? is joy
Who are 2b ? is joy
Who are 2b ? is joy
Who are 2b ? is bob !
Who are 2b ? is bob !
Who are 2b ? is bob !
Who are 2b ? is joy
参数说明:
<diskStore>:当内存缓存中对象数量超过maxElementsInMemory时,将缓存对象写到磁盘缓存中(需对象实现序列化接口)。
<diskStore path="">:用来配置磁盘缓存使用的物理路径,Ehcache磁盘缓存使用的文件后缀名是*.data和*.index。
name:缓存名称,cache的唯一标识(ehcache会把这个cache放到HashMap里)。
maxElementsOnDisk:磁盘缓存中最多可以存放的元素数量,0表示无穷大。
maxElementsInMemory:内存缓存中最多可以存放的元素数量,若放入Cache中的元素超过这个数值,则有以下两种情况。
1)若overflowToDisk=true,则会将Cache中多出的元素放入磁盘文件中。
2)若overflowToDisk=false,则根据memoryStoreEvictionPolicy策略替换Cache中原有的元素。
Eternal:缓存中对象是否永久有效,即是否永驻内存,true时将忽略timeToIdleSeconds和timeToLiveSeconds。
timeToIdleSeconds:缓存数据在失效前的允许闲置时间(单位:秒),仅当eternal=false时使用,默认值是0表示可闲置时间无穷大,此为可选属性即访问这个cache中元素的最大间隔时间,若超过这个时间没有访问此Cache中的某个元素,那么此元素将被从Cache中清除。
timeToLiveSeconds:缓存数据在失效前的允许存活时间(单位:秒),仅当eternal=false时使用,默认值是0表示可存活时间无穷大,即Cache中的某元素从创建到清楚的生存时间,也就是说从创建开始计时,当超过这个时间时,此元素将从Cache中清除。
overflowToDisk:内存不足时,是否启用磁盘缓存(即内存中对象数量达到maxElementsInMemory时,Ehcache会将对象写到磁盘中),会根据标签中path值查找对应的属性值,写入磁盘的文件会放在path文件夹下,文件的名称是cache的名称,后缀名是data。
diskPersistent:是否持久化磁盘缓存,当这个属性的值为true时,系统在初始化时会在磁盘中查找文件名为cache名称,后缀名为index的文件,这个文件中存放了已经持久化在磁盘中的cache的index,找到后会把cache加载到内存,要想把cache真正持久化到磁盘,写程序时注意执行net.sf.ehcache.Cache.put(Element element)后要调用flush()方法。
diskExpiryThreadIntervalSeconds:磁盘缓存的清理线程运行间隔,默认是120秒。
diskSpoolBufferSizeMB:设置DiskStore(磁盘缓存)的缓存区大小,默认是30MB
memoryStoreEvictionPolicy:内存存储与释放策略,即达到maxElementsInMemory限制时,Ehcache会根据指定策略清理内存,共有三种策略,分别为LRU(最近最少使用)、LFU(最常用的)、FIFO(先进先出)。

本文介绍如何在Spring4.x环境中集成Ehcache3.x实现集群缓存功能,包括pom.xml依赖配置、ehcache.xml缓存配置、Spring配置文件示例及InfoCache类的实现。

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