java.lang.NullPointerException

Question

2011-01-24 10:09:44 [net.sf.ehcache.distribution.RMIAsynchronousCacheReplicator]-[WARN] Exception on flushing of replication queue: null. Continuing...
java.lang.NullPointerException
at net.sf.ehcache.distribution.RMISynchronousCacheReplicator.listRemoteCachePeers(RMISynchronousCacheReplicator.java:313)
at net.sf.ehcache.distribution.RMIAsynchronousCacheReplicator.flushReplicationQueue(RMIAsynchronousCacheReplicator.java:305)
at net.sf.ehcache.distribution.RMIAsynchronousCacheReplicator.replicationThreadMain(RMIAsynchronousCacheReplicator.java:122)
at net.sf.ehcache.distribution.RMIAsynchronousCacheReplicator.access$100(RMIAsynchronousCacheReplicator.java:55)
at net.sf.ehcache.distribution.RMIAsynchronousCacheReplicator$ReplicationThread.run(RMIAsynchronousCacheReplicator.java:372)系统经常出现这个异常“是随机什么时候出得没有规律”，但不影响系统使用。
求解释这什么错

Answer 1

RMI是调远程的方法，你什么地方用到net.sf.ehcache.distribution.*的包了 ，贴完整代码看看

Answer 2

<ehcache xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:noNamespaceSchemaLocation="ehcache.xsd">   
    <diskStore path="java.io.tmpdir"/>
   
    <cacheManagerPeerProviderFactory class=
                          "net.sf.ehcache.distribution.RMICacheManagerPeerProviderFactory"
                          properties="peerDiscovery=manual,
                          rmiUrls=//192.168.1.100:40000/sampleCache1|//192.168.1.101:40000/sampleCache1"
                          propertySeparator="," /><cacheManagerPeerListenerFactory 
class="net.sf.ehcache.distribution.RMICacheManagerPeerListenerFactory" 
properties="port=40001, socketTimeoutMillis=2000"/>   
    <defaultCache
            maxElementsInMemory="10000"
            eternal="false"
            timeToIdleSeconds="120"
            timeToLiveSeconds="120"
            overflowToDisk="true"
            diskSpoolBufferSizeMB="30"
            maxElementsOnDisk="10000000"
            diskPersistent="false"
            diskExpiryThreadIntervalSeconds="120"
            memoryStoreEvictionPolicy="LRU"
            />
  
    <cache name="sampleCache11"
           maxElementsInMemory="10000"
           maxElementsOnDisk="1000"
           eternal="false"
           overflowToDisk="true"
           diskSpoolBufferSizeMB="20"
           timeToIdleSeconds="300"
           timeToLiveSeconds="600"
           memoryStoreEvictionPolicy="LFU"
            />    <cache name="sampleCache2"
           maxElementsInMemory="1000"
           eternal="true"
           overflowToDisk="false"
           memoryStoreEvictionPolicy="FIFO"
            />
  
    <cache name="sampleCache3"
           maxElementsInMemory="500"
           eternal="false"
           overflowToDisk="true"
           timeToIdleSeconds="300"
           timeToLiveSeconds="600"
           diskPersistent="true"
           diskExpiryThreadIntervalSeconds="1"
           memoryStoreEvictionPolicy="LFU"
            />    <cache name="sampleCache1"
           maxElementsInMemory="10"
           eternal="false"
           timeToIdleSeconds="100"
           timeToLiveSeconds="100"
           overflowToDisk="false">
        <cacheEventListenerFactory
                class="net.sf.ehcache.distribution.RMICacheReplicatorFactory"/>
        <bootstrapCacheLoaderFactory
                class="net.sf.ehcache.distribution.RMIBootstrapCacheLoaderFactory"/>
    </cache>    <cache name="sampleDistributedCache2"
           maxElementsInMemory="10"
           eternal="false"
           timeToIdleSeconds="100"
           timeToLiveSeconds="100"
           overflowToDisk="false">
        <cacheEventListenerFactory
                class="net.sf.ehcache.distribution.RMICacheReplicatorFactory"
                properties="replicateAsynchronously=false, replicatePuts=false,
                            replicateUpdates=true, replicateUpdatesViaCopy=true,
                            replicateRemovals=false"/>
    </cache>
   
    <cache name="sampleDistributedCache3"
           maxElementsInMemory="10"
           eternal="false"
           timeToIdleSeconds="100"
           timeToLiveSeconds="100"
           overflowToDisk="false">
        <cacheEventListenerFactory
                class="net.sf.ehcache.distribution.RMICacheReplicatorFactory"
                properties="asynchronousReplicationIntervalMillis=200"/>
    </cache>
</ehcache>