ehcache 缓存的使用
合理的使用缓存会极大的提高程序的运行效率。切记：缓存请勿滥用。
配置ehcache与Shiro
shiro初识请查看该文章
https://blog.csdn.net/pyfysf/article/details/81952889
一、导入ehcache的依赖
<!-- https://mvnrepository.com/artifact/net.sf.ehcache/ehcache -->
<dependency>
<groupId>net.sf.ehcache</groupId>
<artifactId>ehcache</artifactId>
<version>2.6.7</version>
<type>pom</type>
</dependency>
二、创建ehcache.xml配置文件
简洁版
<ehcache xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="../config/ehcache.xsd">
<!--缓存的路径 当前配置为系统的临时目录 可以任意修改为任意盘符下的文件夹-->
<diskStore path="java.io.tmpdir"/>
<!--
maxElementsInMemory:内存存储数据的个数
eternal:缓存数据是否永久有效 建议false
timeToIdleSeconds:最大空闲时间 (s) 空闲时间超出配置，清理内存数据
timeToLiveSeconds:存活时间(s)
overflowToDisk: 溢出到磁盘(磁盘最多存储多少个对象) 如果内存超过maxElementsInMemory配置那么放置到配置的磁盘路径上
diskPersistent: 服务器重启时是否保留磁盘数据
diskExpiryThreadIntervalSeconds: 每隔多长时间进行线程扫描
memoryStoreEvictionPolicy:淘汰策略 LRU(最近最少) FIFO(先进先出 Frist in Frist out)
-->
<defaultCache
maxElementsInMemory="10000"
eternal="false"
timeToIdleSeconds="120"
timeToLiveSeconds="120"
overflowToDisk="true"
maxElementsOnDisk="10000000"
diskPersistent="false"
diskExpiryThreadIntervalSeconds="120"
memoryStoreEvictionPolicy="LRU"
/>
<!-- 自定义缓存 -->
<cache
name="ehcacheName"
maxElementsInMemory="10000"
eternal="false"
timeToIdleSeconds="300000"
timeToLiveSeconds="600000"
overflowToDisk="true" />
<!-- 系统缓存 -->
<cache name="sysCache" maxEntriesLocalHeap="100" eternal="true" overflowToDisk="true"/>
</ehcache>
注释版
<ehcache xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="../config/ehcache.xsd">
<!--
The ehcache-failsafe.xml is a default configuration for ehcache, if an ehcache.xml is not configured.
The diskStore element is optional. It must be configured if you have overflowToDisk or diskPersistent enabled
for any cache. If it is not configured, a warning will be issues and java.io.tmpdir will be used.
diskStore has only one attribute - "path". It is the path to the directory where .data and .index files will be created.
If the path is a Java System Property it is replaced by its value in the
running VM.
The following properties are translated:
* user.home - User's home directory
* user.dir - User's current working directory
* java.io.tmpdir - Default temp file path
* ehcache.disk.store.dir - A system property you would normally specify on the command line
e.g. java -Dehcache.disk.store.dir=/u01/myapp/diskdir ...
Subdirectories can be specified below the property e.g. java.io.tmpdir/one
-->
<!--缓存的路径 当前配置为系统的临时目录 可以任意修改为任意盘符下的文件夹-->
<diskStore path="java.io.tmpdir"/>
<!--
Specifies a CacheManagerEventListenerFactory, be used to create a CacheManagerPeerProvider,
which is notified when Caches are added or removed from the CacheManager.
The attributes of CacheManagerEventListenerFactory are:
* class - a fully qualified factory class name
* properties - comma separated properties having meaning only to the factory.
Sets the fully qualified class name to be registered as the CacheManager event listener.
The events include:
* adding a Cache
* removing a Cache
Callbacks to listener methods are synchronous and unsynchronized. It is the responsibility
of the implementer to safely handle the potential performance and thread safety issues
depending on what their listener is doing.
If no class is specified, no listener is created. There is no default.
<cacheManagerEventListenerFactory class="" properties=""/>
-->
<!--
(Enable for distributed operation)
Specifies a CacheManagerPeerProviderFactory which will be used to create a
CacheManagerPeerProvider, which discovers other CacheManagers in the cluster.
The attributes of cacheManagerPeerProviderFactory are:
* class - a fully qualified factory class name
* properties - comma separated properties having meaning only to the factory.
Ehcache comes with a built-in RMI-based distribution system with two means of discovery of
CacheManager peers participating in the cluster:
* automatic, using a multicast group. This one automatically discovers peers and detects
changes such as peers entering and leaving the group
* manual, using manual rmiURL configuration. A hardcoded list of peers is provided at
configuration time.
Configuring Automatic Discovery:
Automatic discovery is configured as per the following example:
<cacheManagerPeerProviderFactory
class="net.sf.ehcache.distribution.RMICacheManagerPeerProviderFactory"
properties="peerDiscovery=automatic, multicastGroupAddress=230.0.0.1,
multicastGroupPort=4446, timeToLive=32"/>
Valid properties are:
* peerDiscovery (mandatory) - specify "automatic"
* multicastGroupAddress (mandatory) - specify a valid multicast group address
* multicastGroupPort (mandatory) - specify a dedicated port for the multicast heartbeat
traffic
* timeToLive - specify a value between 0 and 255 which determines how far the packets will propagate.
By convention, the restrictions are:
0 - the same host
1 - the same subnet
32 - the same site
64 - the same region
128 - the same continent
255 - unrestricted
Configuring Manual Discovery:
Manual discovery is configured as per the following example:
<cacheManagerPeerProviderFactory class=
"net.sf.ehcache.distribution.RMICacheManagerPeerProviderFactory"
properties="peerDiscovery=manual,
rmiUrls=//server1:40000/sampleCache1|//server2:40000/sampleCache1
| //server1:40000/sampleCache2|//server2:40000/sampleCache2"/>
Valid properties are:
* peerDiscovery (mandatory) - specify "manual"
* rmiUrls (mandatory) - specify a pipe separated list of rmiUrls, in the form
//hostname:port
The hostname is the hostname of the remote CacheManager peer. The port is the listening
port of the RMICacheManagerPeerListener of the remote CacheManager peer.
<cacheManagerPeerProviderFactory
class="net.sf.ehcache.distribution.RMICacheManagerPeerProviderFactory"
properties="peerDiscovery=automatic,
multicastGroupAddress=230.0.0.1,
multicastGroupPort=4446, timeToLive=1"/>
-->
<!--
(Enable for distributed operation)
Specifies a CacheManagerPeerListenerFactory which will be used to create a
CacheManagerPeerListener, which
listens for messages from cache replicators participating in the cluster.
The attributes of cacheManagerPeerListenerFactory are:
class - a fully qualified factory class name
properties - comma separated properties having meaning only to the factory.
Ehcache comes with a built-in RMI-based distribution system. The listener component is
RMICacheManagerPeerListener which is configured using
RMICacheManagerPeerListenerFactory. It is configured as per the following example:
<cacheManagerPeerListenerFactory
class="net.sf.ehcache.distribution.RMICacheManagerPeerListenerFactory"
properties="hostName=fully_qualified_hostname_or_ip,
port=40001,
socketTimeoutMillis=120000"/>
All properties are optional. They are:
* hostName - the hostName of the host the listener is running on. Specify
where the host is multihomed and you want to control the interface over which cluster
messages are received. Defaults to the host name of the default interface if not
specified.
* port - the port the listener listens on. This defaults to a free port if not specified.
* socketTimeoutMillis - the number of ms client sockets will stay open when sending
messages to the listener. This should be long enough for the slowest message.
If not specified it defaults 120000ms.
<cacheManagerPeerListenerFactory
class="net.sf.ehcache.distribution.RMICacheManagerPeerListenerFactory"/>
-->
<!-- Cache configuration.
The following attributes are required.
name:
Sets the name of the cache. This is used to identify the cache. It must be unique.
maxElementsInMemory:
Sets the maximum number of objects that will be created in memory
maxElementsOnDisk:
Sets the maximum number of objects that will be maintained in the DiskStore
The default value is zero, meaning unlimited.
eternal:
Sets whether elements are eternal. If eternal, timeouts are ignored and the
element is never expired.
overflowToDisk:
Sets whether elements can overflow to disk when the in-memory cache
has reached the maxInMemory limit.
The following attributes are optional.
timeToIdleSeconds:
Sets the time to idle for an element before it expires.
i.e. The maximum amount of time between accesses before an element expires
Is only used if the element is not eternal.
Optional attribute. A value of 0 means that an Element can idle for infinity.
The default value is 0.
timeToLiveSeconds:
Sets the time to live for an element before it expires.
i.e. The maximum time between creation time and when an element expires.
Is only used if the element is not eternal.
Optional attribute. A value of 0 means that and Element can live for infinity.
The default value is 0.
diskPersistent:
Whether the disk store persists between restarts of the Virtual Machine.
The default value is false.
diskExpiryThreadIntervalSeconds:
The number of seconds between runs of the disk expiry thread. The default value
is 120 seconds.
diskSpoolBufferSizeMB:
This is the size to allocate the DiskStore for a spool buffer. Writes are made
to this area and then asynchronously written to disk. The default size is 30MB.
Each spool buffer is used only by its cache. If you get OutOfMemory errors consider
lowering this value. To improve DiskStore performance consider increasing it. Trace level
logging in the DiskStore will show if put back ups are occurring.
memoryStoreEvictionPolicy:
Policy would be enforced upon reaching the maxElementsInMemory limit. Default
policy is Least Recently Used (specified as LRU). Other policies available -
First In First Out (specified as FIFO) and Less Frequently Used
(specified as LFU)
Cache elements can also contain sub elements which take the same format of a factory class
and properties. Defined sub-elements are:
* cacheEventListenerFactory - Enables registration of listeners for cache events, such as
put, remove, update, and expire.
* bootstrapCacheLoaderFactory - Specifies a BootstrapCacheLoader, which is called by a
cache on initialisation to prepopulate itself.
Each cache that will be distributed needs to set a cache event listener which replicates
messages to the other CacheManager peers. For the built-in RMI implementation this is done
by adding a cacheEventListenerFactory element of type RMICacheReplicatorFactory to each
distributed cache's configuration as per the following example:
<cacheEventListenerFactory class="net.sf.ehcache.distribution.RMICacheReplicatorFactory"
properties="replicateAsynchronously=true,
replicatePuts=true,
replicateUpdates=true,
replicateUpdatesViaCopy=true,
replicateRemovals=true "/>
The RMICacheReplicatorFactory recognises the following properties:
* replicatePuts=true|false - whether new elements placed in a cache are
replicated to others. Defaults to true.
* replicateUpdates=true|false - whether new elements which override an
element already existing with the same key are replicated. Defaults to true.
* replicateRemovals=true - whether element removals are replicated. Defaults to true.
* replicateAsynchronously=true | false - whether replications are
asynchronous (true) or synchronous (false). Defaults to true.
* replicateUpdatesViaCopy=true | false - whether the new elements are
copied to other caches (true), or whether a remove message is sent. Defaults to true.
* asynchronousReplicationIntervalMillis=<number of milliseconds> - The asynchronous
replicator runs at a set interval of milliseconds. The default is 1000. The minimum
is 10. This property is only applicable if replicateAsynchronously=true
The RMIBootstrapCacheLoader bootstraps caches in clusters where RMICacheReplicators are
used. It is configured as per the following example:
<bootstrapCacheLoaderFactory
class="net.sf.ehcache.distribution.RMIBootstrapCacheLoaderFactory"
properties="bootstrapAsynchronously=true, maximumChunkSizeBytes=5000000"/>
The RMIBootstrapCacheLoaderFactory recognises the following optional properties:
* bootstrapAsynchronously=true|false - whether the bootstrap happens in the background
after the cache has started. If false, bootstrapping must complete before the cache is
made available. The default value is true.
* maximumChunkSizeBytes=<integer> - Caches can potentially be very large, larger than the
memory limits of the VM. This property allows the bootstraper to fetched elements in
chunks. The default chunk size is 5000000 (5MB).
-->
<!--
Mandatory Default Cache configuration. These settings will be applied to caches
created programmtically using CacheManager.add(String cacheName)
-->
<!--
maxElementsInMemory:内存存储数据的个数
eternal:缓存数据是否永久有效 建议false
timeToIdleSeconds:最大空闲时间 (s) 空闲时间超出配置，清理内存数据
timeToLiveSeconds:存活时间(s)
overflowToDisk: 溢出到磁盘(磁盘最多存储多少个对象) 如果内存超过maxElementsInMemory配置那么放置到配置的磁盘路径上
diskPersistent: 服务器重启时是否保留磁盘数据
diskExpiryThreadIntervalSeconds: 每隔多长时间进行线程扫描
memoryStoreEvictionPolicy:淘汰策略 LRU(最近最少) FIFO(先进先出 Frist in Frist out)
-->
<defaultCache
maxElementsInMemory="10000"
eternal="false"
timeToIdleSeconds="120"
timeToLiveSeconds="120"
overflowToDisk="true"
maxElementsOnDisk="10000000"
diskPersistent="false"
diskExpiryThreadIntervalSeconds="120"
memoryStoreEvictionPolicy="LRU"
/>
<!-- 自定义缓存 -->
<cache
name="ehcacheName"
maxElementsInMemory="10000"
eternal="false"
timeToIdleSeconds="300000"
timeToLiveSeconds="600000"
overflowToDisk="true" />
<!-- 系统缓存 -->
<cache name="sysCache" maxEntriesLocalHeap="100" eternal="true" overflowToDisk="true"/>
</ehcache>
三、配置ehcacheManager与shiro进行结合
<!--注册shiro的缓存管理器 将其注册为安全管理器
在shiro-all.jar中
-->
<bean id="cacheManager" class="org.apache.shiro.cache.ehcache.EhCacheManager">
<!--指定ehcache的配置文件-->
<property name="cacheManagerConfigFile" value="classpath:ehcache.xml"></property>
</bean>
<!--配置安全管理器-->
<bean id="securityManager" class="org.apache.shiro.web.mgt.DefaultWebSecurityManager">
<property name="realm" ref="myRealm"/>
<property name="cacheManager" ref="cacheManager"/>
</bean>
附录(EhcacheUtils)：
/**
* Cache工具类
*/
public class CacheUtils {
private static CacheManager cacheManager;
private static final String SYS_CACHE = "sysCache";
public final static Byte[] locks = new Byte[0];
/**
* 获取SYS_CACHE缓存
*
* @param key
* @return
*/
public static Object get(String key) {
return get(SYS_CACHE, key);
}
/**
* 写入SYS_CACHE缓存
*
* @param key
* @return
*/
public static void put(String key, Object value) {
put(SYS_CACHE, key, value);
}
/**
* @param key
* @return
*/
public static void remove(String key) {
remove(SYS_CACHE, key);
}
/**
* 获取缓存
*
* @param cacheName
* @param key
* @return
*/
public static Object get(String cacheName, String key) {
Element element = getCache(cacheName).get(key);
return element == null ? null : element.getObjectValue();
}
/**
* 写入缓存
*
* @param cacheName
* @param key
* @param value
*/
public static void put(String cacheName, String key, Object value) {
Element element = new Element(key, value);
getCache(cacheName).put(element);
}
/**
* 从缓存中移除
*
* @param cacheName
* @param key
*/
public static void remove(String cacheName, String key) {
getCache(cacheName).remove(key);
}
public static void removeAll(String cacheName) {
getCache(cacheName).removeAll();
}
/**
* @param cacheName
* @return
*/
private static Cache getCache(String cacheName) {
if (cacheManager == null) {
synchronized (locks) {
if (cacheManager == null) {
cacheManager = ((CacheManager) SpringContextUtil.getBean("cacheManager"));
}
}
}
Cache cache = cacheManager.getCache(cacheName);
if (cache == null) {
cacheManager.addCache(cacheName);
cache = cacheManager.getCache(cacheName);
cache.getCacheConfiguration().setEternal(true);
}
return cache;
}
public static CacheManager getCacheManager() {
return cacheManager;
}
}