有沒有辦法可以避免這種情況，並乾淨地關閉？
15:06:35.054 [pool-7-thread-2] | ERROR o.a.ftpserver.impl.DefaultFtpHandler - Exception caught, closing session java.lang.AbstractMethodError: org.apache.ftpserver.listener.nio.FtpHandlerAdapter.inputClosed(Lorg/apache/mina/core/session/IoSession;)V at org.apache.mina.core.filterchain.DefaultIoFilterChain$TailFilter.inputClosed(DefaultIoFilterChain.java:834) ~[mina-core-2.0.8.jar:na] at org.apache.mina.core.filterchain.DefaultIoFilterChain.callNextInputClosed(DefaultIoFilterChain.java:611) ~[mina-core-2.0.8.jar:na] at org.apache.mina.core.filterchain.DefaultIoFilterChain.access$1200(DefaultIoFilterChain.java:48) ~[mina-core-2.0.8.jar:na] at org.apache.mina.core.filterchain.DefaultIoFilterChain$EntryImpl$1.inputClosed(DefaultIoFilterChain.java:938) ~[mina-core-2.0.8.jar:na] at org.apache.mina.core.filterchain.IoFilterAdapter.inputClosed(IoFilterAdapter.java:134) ~[mina-core-2.0.8.jar:na] at org.apache.mina.core.filterchain.DefaultIoFilterChain.callNextInputClosed(DefaultIoFilterChain.java:611) ~[mina-core-2.0.8.jar:na] at org.apache.mina.core.filterchain.DefaultIoFilterChain.access$1200(DefaultIoFilterChain.java:48) ~[mina-core-2.0.8.jar:na] at org.apache.mina.core.filterchain.DefaultIoFilterChain$EntryImpl$1.inputClosed(DefaultIoFilterChain.java:938) ~[mina-core-2.0.8.jar:na] at org.apache.mina.core.filterchain.IoFilterAdapter.inputClosed(IoFilterAdapter.java:134) ~[mina-core-2.0.8.jar:na] at org.apache.mina.core.filterchain.DefaultIoFilterChain.callNextInputClosed(DefaultIoFilterChain.java:611) ~[mina-core-2.0.8.jar:na] at org.apache.mina.core.filterchain.DefaultIoFilterChain.access$1200(DefaultIoFilterChain.java:48) ~[mina-core-2.0.8.jar:na] at org.apache.mina.core.filterchain.DefaultIoFilterChain$EntryImpl$1.inputClosed(DefaultIoFilterChain.java:938) ~[mina-core-2.0.8.jar:na] at org.apache.mina.core.filterchain.IoFilterAdapter.inputClosed(IoFilterAdapter.java:134) ~[mina-core-2.0.8.jar:na] at org.apache.mina.core.filterchain.DefaultIoFilterChain.callNextInputClosed(DefaultIoFilterChain.java:611) ~[mina-core-2.0.8.jar:na] at org.apache.mina.core.filterchain.DefaultIoFilterChain.access$1200(DefaultIoFilterChain.java:48) ~[mina-core-2.0.8.jar:na] at org.apache.mina.core.filterchain.DefaultIoFilterChain$EntryImpl$1.inputClosed(DefaultIoFilterChain.java:938) ~[mina-core-2.0.8.jar:na] at org.apache.mina.core.filterchain.IoFilterAdapter.inputClosed(IoFilterAdapter.java:134) ~[mina-core-2.0.8.jar:na] at org.apache.mina.core.filterchain.DefaultIoFilterChain.callNextInputClosed(DefaultIoFilterChain.java:611) ~[mina-core-2.0.8.jar:na] at org.apache.mina.core.filterchain.DefaultIoFilterChain.access$1200(DefaultIoFilterChain.java:48) ~[mina-core-2.0.8.jar:na] at org.apache.mina.core.filterchain.DefaultIoFilterChain$EntryImpl$1.inputClosed(DefaultIoFilterChain.java:938) ~[mina-core-2.0.8.jar:na] at org.apache.mina.core.filterchain.IoFilterAdapter.inputClosed(IoFilterAdapter.java:134) ~[mina-core-2.0.8.jar:na] at org.apache.mina.core.filterchain.DefaultIoFilterChain.callNextInputClosed(DefaultIoFilterChain.java:611) ~[mina-core-2.0.8.jar:na] at org.apache.mina.core.filterchain.DefaultIoFilterChain.access$1200(DefaultIoFilterChain.java:48) ~[mina-core-2.0.8.jar:na] at org.apache.mina.core.filterchain.DefaultIoFilterChain$EntryImpl$1.inputClosed(DefaultIoFilterChain.java:938) ~[mina-core-2.0.8.jar:na] at org.apache.mina.core.filterchain.IoFilterAdapter.inputClosed(IoFilterAdapter.java:134) ~[mina-core-2.0.8.jar:na] at org.apache.mina.core.filterchain.DefaultIoFilterChain.callNextInputClosed(DefaultIoFilterChain.java:611) ~[mina-core-2.0.8.jar:na] at org.apache.mina.core.filterchain.DefaultIoFilterChain.fireInputClosed(DefaultIoFilterChain.java:604) ~[mina-core-2.0.8.jar:na] at org.apache.mina.core.polling.AbstractPollingIoProcessor.read(AbstractPollingIoProcessor.java:729) ~[mina-core-2.0.8.jar:na] at org.apache.mina.core.polling.AbstractPollingIoProcessor.process(AbstractPollingIoProcessor.java:668) ~[mina-core-2.0.8.jar:na] at org.apache.mina.core.polling.AbstractPollingIoProcessor.process(AbstractPollingIoProcessor.java:657) ~[mina-core-2.0.8.jar:na] at org.apache.mina.core.polling.AbstractPollingIoProcessor.access$600(AbstractPollingIoProcessor.java:67) ~[mina-core-2.0.8.jar:na] at org.apache.mina.core.polling.AbstractPollingIoProcessor$Processor.run(AbstractPollingIoProcessor.java:1121) ~[mina-core-2.0.8.jar:na] at org.apache.mina.util.NamePreservingRunnable.run(NamePreservingRunnable.java:64) ~[mina-core-2.0.8.jar:na] at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145) ~[na:1.7.0_67] at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615) ~[na:1.7.0_67] at java.lang.Thread.run(Thread.java:745) [na:1.7.0_67]