Mybatis配置ehcache报错（说未序列化），求解！~！！?报错

VO类已经序列化（部分代码如下）：

import java.io.Serializable;




public class Products implements Serializable{


/**
* 
*/
private static final long serialVersionUID = -6193310436318894856L;

ehcache.xml文件配置如下：

<ehcache xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="../config/ehcache.xsd">


    <diskStore path="java.io.tmpdir"/>

    <defaultCache
            maxElementsInMemory="10000"
            eternal="false"
            timeToIdleSeconds="120"
            timeToLiveSeconds="120"
            overflowToDisk="true"
            maxElementsOnDisk="10000000"
            diskPersistent="false"
            diskExpiryThreadIntervalSeconds="120"
            memoryStoreEvictionPolicy="LRU"
            />
</ehcache>

报错：

2013-11-13 13:53:12,901 - net.sf.ehcache.store.disk.DiskStorageFactory -78860 [org%002emapper%002e%0050roducts.data] ERROR net.sf.ehcache.store.disk.DiskStorageFactory  - Disk Write of 1744313901:5183834706:org.mapper.Products.selectAllByOneBusid:0:2147483647:SELECT * 
        FROM PRODUCTS 
        WHERE BUSINESSID=?
        ORDER BY PROLIKE DESC:5 failed:  
java.io.NotSerializableException: org.apache.ibatis.cache.CacheKey
at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1156)
at java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1509)
at java.io.ObjectOutputStream.defaultWriteObject(ObjectOutputStream.java:416)
at net.sf.ehcache.Element.writeObject(Element.java:835)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at java.io.ObjectStreamClass.invokeWriteObject(ObjectStreamClass.java:945)
at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1461)
at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1392)
at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1150)
at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:326)
at net.sf.ehcache.util.MemoryEfficientByteArrayOutputStream.serialize(MemoryEfficientByteArrayOutputStream.java:97)
at net.sf.ehcache.store.disk.DiskStorageFactory.serializeElement(DiskStorageFactory.java:405)
at net.sf.ehcache.store.disk.DiskStorageFactory.write(DiskStorageFactory.java:384)
at net.sf.ehcache.store.disk.DiskStorageFactory$DiskWriteTask.call(DiskStorageFactory.java:485)
at net.sf.ehcache.store.disk.DiskStorageFactory$PersistentDiskWriteTask.call(DiskStorageFactory.java:1088)
at net.sf.ehcache.store.disk.DiskStorageFactory$PersistentDiskWriteTask.call(DiskStorageFactory.java:1072)
at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:303)
at java.util.concurrent.FutureTask.run(FutureTask.java:138)
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$301(ScheduledThreadPoolExecutor.java:98)
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:207)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
at java.lang.Thread.run(Thread.java:619)

请问除了vo类要序列化，还有什么需要序列化？

==================update==========================

报错点在这里：

不明白的是居然该对象不是Serializable对象，但是我明明已经实现了Serializable接口，但是却实例化失败了，这究竟是怎么回事，弄了很久没想明白？恳请各位帮忙。。