Ehcache简单使用

Ehcache是Java虚拟机级的缓存，其可以用于许多地方。如：被Hibernate用作二级缓存，Web页缓存、Web页片段缓存、Session同步等。

官方主页：http://ehcache.org/

主要测试类：

package my.test.ehcache1;

import java.io.InputStream;
import java.lang.management.ManagementFactory;

import javax.management.MBeanServer;

import net.sf.ehcache.Cache;
import net.sf.ehcache.CacheManager;
import net.sf.ehcache.Element;
import net.sf.ehcache.management.ManagementService;

public class EHCacheTest {

public static void main(String[] args) {
InputStream is = EHCacheTest.class
.getResourceAsStream("/my/test/ehcache1/ehcache.xml");
//读入配置
CacheManager cacheManager = new CacheManager(is);
//打印初始缓存
String[] cacheNames = cacheManager.getCacheNames();
printNames(cacheNames);
//移除缓存
cacheManager.removeCache("sampleDistributedCache1");
cacheNames = cacheManager.getCacheNames();
printNames(cacheNames);

//新建缓存
Cache cache = new Cache("Test1", 100, true, false, 10, 10);
cacheManager.addCache(cache);
cacheNames = cacheManager.getCacheNames();
printNames(cacheNames);
cache.put(new Element("test1", "value1"));

//得到缓存并插入值（这里监听器被调用）
cache = cacheManager.getCache("sampleCache3");
for (int i = 0; i < 20; i++) {
cache.put(new Element("key" + i, "value" + i));
}
cache.get("key10");

// distributed -- rmi同步
cache = cacheManager.getCache("sampleDistributedCache2");
for (int i = 0; i < 100; i++) {
cache.put(new Element("key" + i , "value" + i));
}

//注册被管理的Bean
// JMX -- jconsole(MBeanServer)
MBeanServer mBeanServer = ManagementFactory.getPlatformMBeanServer();
ManagementService.registerMBeans(cacheManager, mBeanServer, true, true,
true, true);

for (int i = 0; i < 10; i++) {
Element temp = cache.get("ehcache");
if (temp != null) {
System.out.println(temp.getValue());
} else {
System.out.println("NotFound");
}
try {
Thread.sleep(10000);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}

private static void printNames(String[] names) {
System.out.println("=======================");
for (int i = 0; i < names.length; i++) {
System.out.println(names[i]);
}
}

}

Cache事件监听器工厂类：

package my.test.ehcache1;

import java.util.Properties;

import net.sf.ehcache.event.CacheEventListener;
import net.sf.ehcache.event.CacheEventListenerFactory;

public class CacheEvtLstnFac extends CacheEventListenerFactory {

@Override
public CacheEventListener createCacheEventListener(Properties arg0) {
return new CacheEvtLstn();
}

}

Cache事件监听器类：

package my.test.ehcache1;

import net.sf.ehcache.CacheException;
import net.sf.ehcache.Ehcache;
import net.sf.ehcache.Element;
import net.sf.ehcache.event.CacheEventListener;

public class CacheEvtLstn implements CacheEventListener {

public Object clone() {
return this;
}

public void dispose() {
// TODO Auto-generated method stub

}

public void notifyElementEvicted(Ehcache arg0, Element arg1) {
System.out.println(arg1.getKey() + "=" + arg1.getValue()
+ " has been evicted");
}

public void notifyElementExpired(Ehcache arg0, Element arg1) {
// TODO Auto-generated method stub

}

public void notifyElementPut(Ehcache arg0, Element arg1)
throws CacheException {
System.out.println(arg1.getKey() + "=" + arg1.getValue()
+ " has been added");
}

public void notifyElementRemoved(Ehcache arg0, Element arg1)
throws CacheException {
// TODO Auto-generated method stub

}

public void notifyElementUpdated(Ehcache arg0, Element arg1)
throws CacheException {
// TODO Auto-generated method stub

}

public void notifyRemoveAll(Ehcache arg0) {
// TODO Auto-generated method stub

}

}

xml配置文件：更改官方包中的样例文件ehcache.xml中的sampleCache3为如下形式：

<cache name="sampleCache3"
maxElementsInMemory="10"
eternal="false"
overflowToDisk="false"
timeToIdleSeconds="300"
timeToLiveSeconds="600"
diskPersistent="false"
diskExpiryThreadIntervalSeconds="1"
memoryStoreEvictionPolicy="LFU">
<cacheEventListenerFactory class="my.test.ehcache1.CacheEvtLstnFac" properties=""/>
</cache>

输出结果：

2009-12-13 11:36:02 net.sf.ehcache.distribution.RMICacheManagerPeerListener <init>
警告: Explicitly setting the listener hostname to 'localhost' is not recommended. It will only work if all CacheManager peers are on the same machine.
=======================
sampleDistributedCache2
sampleCache2
sampleCache1
sample/DistributedCache3
sampleDistributedCache1
sampleCache3
=======================
sampleDistributedCache2
sampleCache2
sampleCache1
sample/DistributedCache3
sampleCache3
=======================
sampleDistributedCache2
sampleCache2
Test1
sampleCache1
sample/DistributedCache3
sampleCache3
key0=value0 has been added
key1=value1 has been added
key2=value2 has been added
key3=value3 has been added
key4=value4 has been added
key5=value5 has been added
key6=value6 has been added
key7=value7 has been added
key8=value8 has been added
key9=value9 has been added
key0=value0 has been evicted
key10=value10 has been added
key2=value2 has been evicted
key11=value11 has been added
key1=value1 has been evicted
key12=value12 has been added
key4=value4 has been evicted
key13=value13 has been added
key9=value9 has been evicted
key14=value14 has been added
key7=value7 has been evicted
key15=value15 has been added
key5=value5 has been evicted
key16=value16 has been added
key14=value14 has been evicted
key17=value17 has been added
key12=value12 has been evicted
key18=value18 has been added
key8=value8 has been evicted
key19=value19 has been added
NotFound

解释：

首先打印配置文件中的cache名

接着移除了名为“sampleDistributedCache1”的cache，再打印cache名

再添加"Test1"cache，再打印cache名

接着向sampleCache3插入值，因为这个注册了监听器，所以监听器的会输出相应信息

这里配置了maxElementsInMemory="10"，overflowToDisk="false"，表明最多只能存10个条目在内存中，并且不能使用磁盘，因此从10-19添加的条目，会将之前存储的条目从缓存中移除。

由于将CacheManager注册到了本地管理BeanServer，所以可以通过jdk的jconsole命令查看管理Bean，如图：