在android中创建EHCache实例时的EHCache

Question

我试图在Android中使用ehCache，并得到以下错误

java.lang.ExceptionInInitializerError
    at net.sf.ehcache.EhcacheDefaultClassLoader.getInstance(EhcacheDefaultClassLoader.java:29)
    at net.sf.ehcache.config.Configuration.<init>(Configuration.java:208)
    at net.sf.ehcache.config.ConfigurationFactory.parseConfiguration(ConfigurationFactory.java:152)
    at net.sf.ehcache.config.ConfigurationFactory.parseConfiguration(ConfigurationFactory.java:103)
    at net.sf.ehcache.config.ConfigurationFactory.parseConfiguration(ConfigurationFactory.java:140)
    at net.sf.ehcache.CacheManager.newInstance(CacheManager.java:892)
    at net.sf.ehcache.CacheManager.create(CacheManager.java:873)
    at net.sf.ehcache.CacheManager.getInstance(CacheManager.java:907)

Caused by: java.lang.NullPointerException: parentLoader == null && !nullAllowed
    at java.lang.ClassLoader.<init>(ClassLoader.java:210)
    at java.lang.ClassLoader.<init>(ClassLoader.java:202)
    at net.sf.ehcache.EhcacheDefaultClassLoader.<init>(EhcacheDefaultClassLoader.java:35)
    at net.sf.ehcache.EhcacheDefaultClassLoader.<clinit>(EhcacheDefaultClassLoader.java:26)
    at net.sf.ehcache.EhcacheDefaultClassLoader.getInstance(EhcacheDefaultClassLoader.java:29) 
    at net.sf.ehcache.config.Configuration.<init>(Configuration.java:208) 
    at net.sf.ehcache.config.ConfigurationFactory.parseConfiguration(ConfigurationFactory.java:152) 
    at net.sf.ehcache.config.ConfigurationFactory.parseConfiguration(ConfigurationFactory.java:103) 
    at net.sf.ehcache.config.ConfigurationFactory.parseConfiguration(ConfigurationFactory.java:140) 
    at net.sf.ehcache.CacheManager.newInstance(CacheManager.java:892) 
    at net.sf.ehcache.CacheManager.create(CacheManager.java:873) 
    at net.sf.ehcache.CacheManager.getInstance(CacheManager.java:907)

下面是我试图初始化的代码

private static Cache getCache(String cacheName) throws IllegalStateException{
    CacheManager cacheManager = CacheManager.getInstance();
    Cache cache;
    if(!cacheManager.cacheExists(cacheName)) {
        cacheManager.addCache(cacheName);
    }
    cache = cacheManager.getCache(cacheName);
    return cache;
}

看起来EHCache不能在安卓系统中工作？有人能给这个放点光吗？在得到错误后，我还在res/xml/ ehcache.xml 中放置了一个配置为

<ehcache xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"  xsi:noNamespaceSchemaLocation="ehcache.xsd" updateCheck="true"  monitoring="autodetect" dynamicConfig="true">

    <!-- By default, Ehcache stored the cached files in temp folder. -->    <!-- <diskStore path="java.io.tmpdir" /> -->

    <!-- Ask Ehcache to store cache in this path -->    <!--<diskStore path="c:\\cache" /> -->

    <!-- Sample cache named cache1
    This cache contains a maximum in memory of 10000 elements, and will expire
    an element if it is idle for more than 5 minutes and lives for more than
    10 minutes.

    If there are more than 10000 elements it will overflow to the
    disk cache, which in this configuration will go to wherever java.io.tmp is
    defined on your system. On a standard Linux system this will be /tmp" 
    -->     
    <cache name="cache1" maxEntriesLocalHeap="10000" maxEntriesLocalDisk="1000" eternal="false" diskSpoolBufferSizeMB="20" timeToIdleSeconds="300" timeToLiveSeconds="600" memoryStoreEvictionPolicy="LFU" transactionalMode="off">         
        <persistence strategy="localTempSwap" />
    </cache>

</ehcache>

Answer 1

Ehcache无法找到ehcach.xml文件。它不知道res/xml文件夹。

因此，尝试以这种方式以编程方式配置缓存(ehcache 2.10)：

// create default CacheManager
Configuration config = new Configuration();
config.setName("Mngmt");
// [...]
CacheManager cacheManager = CacheManager.create(config);

int maxEntriesLocalHeap = 100;
String cachName = "cacheName";
Cache cache = new Cache(
  new CacheConfiguration(cachName, maxEntriesLocalHeap)
    .memoryStoreEvictionPolicy(MemoryStoreEvictionPolicy.LFU)
    .eternal(false)
    .timeToLiveSeconds(120)
    .timeToIdleSeconds(60)
    .diskExpiryThreadIntervalSeconds(0));
cacheManager.addCache(cache);

更多信息，您可以在这里找到：以编程方式创建缓存