Tomcat 拋出 Cannot serialize session attribute 異常

今天team成員遇到個很奇怪的問題，在啟動和關閉Tomcat 6時, 拋出如下異常：Cannot serialize session attribute XXX  for 。我很是納悶，到apache官網查看了下，發現tomcat 會試圖 serialize存在的session資源. 如果 sessions中相關的對象沒有實現 serializable 介面, 就會出現Cannot serialize session attribute XXX  for  異常。由於開始對某個類實現了Serializable介面，啟動了tomcat，然後又取消實現Serializable介面，重啟tomcat就報錯了。原文如下：

Because when you shutdown tomcat, it tries to serial all objects within
the session scope.  The
class you are referring to
'org.apache.commons.fileupload.DeferredFileOutputStream' does not
implement 'java.io.Serializable' and therefore tomcat throws this
exception when trying to serialize it.

Whilst I don't know what the class
'org.apache.catalina.session.StandardManager' does, presumably is
performs a check to see if an object stored within the session is
serializable before trying to
write it disk, or it might remove non-serializable object from the
session scope on shutdown.

如果你不想看到該異常, 也不想儲存session. 那麼你可以在項目部署描述檔案中(如. test.xml,)(instead of just exploding the war)  的  <Context> tags中間 加上 :

<Manager className="org.apache.catalina.session.PersistentManager"saveOnRestart="false"/>

這樣 tomcat 在關閉的時候就不會儲存session資源了.你也可以在server.xml中指定上面的值. 這也所有的程式都使用這個設定了.