dubbo调用服务出现如下异常

dubbo调⽤服务出现如下异常
log4j:WARN No appenders could be found for logger (org.springframework.context.support.ClassPathXmlApplicationContext).
log4j:WARN Please initialize the log4j system properly.
log4j:WARN See /log4j/1.2/faq.html#noconfig for more info.
Exception in thread "main" com.alibaba.dubbo.rpc.RpcException: Failed to invoke the method IFtpHdfsFileTransfer in the service com.cetc.di.io.manager.IFTPtoHDFSDubboService. Tried 3 times of the providers [172.28.3.40:21000] (1/1) from ng.IllegalStateException: Serialized class com.cetc.di.io.manager.FTPtoHDFSReturn must implement java.io.Serializable
at .caucho.hessian.io.SerializerFactory.getDefaultSerializer(SerializerFactory.java:261)
at .caucho.hessian.io.SerializerFactory.getSerializer(SerializerFactory.java:233)
at .caucho.hessian.io.Hessian2Output.writeObject(Hessian2Output.java:406)
at mon.serialize.support.hessian.Hessian2ObjectOutput.writeObject(Hessian2ObjectOutput.java:92)
at com.alibaba.dubbo.rpc.protocol.dubbo.DubboCodec.encodeResponseData(DubboCodec.java:200)
at com.alibaba.dubbo.remoting.exchange.codec.ExchangeCodec.encodeResponse(ExchangeCodec.java:273)
at com.alibaba.dubbo.remoting.exchange.codec.ExchangeCodec.encode(ExchangeCodec.java:77)
at com.alibaba.dubbo.rpc.protocol.dubbo.DubboCountCodec.encode(DubboCountCodec.java:41)
at tyCodecAdapter$InternalEncoder.encode(NettyCodecAdapter.java:82)
at ty.handler.codec.oneone.OneToOneEncoder.doEncode(OneToOneEncoder.java:66)
at ty.handler.codec.oneone.OneToOneEncoder.handleDownstream(OneToOneEncoder.java:59)
at ty.channel.DefaultChannelPipeline.sendDownstream(DefaultChannelPipeline.java:591)
at ty.channel.DefaultChannelPipeline$DefaultChannelHandlerContext.sendDownstream(DefaultChannelPipeline.java:784)
at ty.channel.SimpleChannelHandler.writeRequested(SimpleChannelHandler.java:292)
at tyHandler.writeRequested(NettyHandler.java:99)
at ty.channel.SimpleChannelHandler.handleDownstream(SimpleChannelHandler.java:254)
at ty.channel.DefaultChannelPipeline.sendDownstream(DefaultChannelPipeline.java:591)
at ty.channel.DefaultChannelPipeline.sendDownstream(DefaultChannelPipeline.java:582)
at ty.channel.Channels.write(Channels.java:704)
at ty.channel.Channels.write(Channels.java:671)
at ty.channel.AbstractChannel.write(AbstractChannel.java:248)
at tyChannel.send(NettyChannel.java:98)
at com.alibaba.dubbo.remoting.transport.AbstractPeer.send(AbstractPeer.java:51)
at com.alibaba.dubbo.remoting.exchange.support.header.HeaderExchangeHandler.received(HeaderExchangeHandler.java:171)
at com.alibaba.dubbo.remoting.transport.DecodeHandler.received(DecodeHandler.java:52)
at com.alibaba.dubbo.remoting.transport.dispather.ChannelEventRunnable.run(ChannelEventRunnable.java:82)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
at ng.Thread.run(Thread.java:745)
at com.alibaba.dubbo.rpc.cluster.support.FailoverClusterInvoker.doInvoke(FailoverClusterInvoker.java:101)
at com.alibaba.dubbo.rpc.cluster.support.AbstractClusterInvoker.invoke(AbstractClusterInvoker.java:226)
at com.alibaba.dubbo.rpc.cluster.support.wrapper.MockClusterInvoker.invoke(MockClusterInvoker.java:72)
at com.alibaba.dubbo.rpc.proxy.InvokerInvocationHandler.invoke(InvokerInvocationHandler.java:52)
at mon.bytecode.proxy0.IFtpHdfsFileTransfer(proxy0.java)
at com.cetc.di.io.manager.Consumer.main(Consumer.java:20)
Caused by: com.alibaba.dubbo.remoting.RemotingException: Failed to send response: Response [id=2, version=2.0.0, status=20, event=false, error=null, result=RpcResult [result=com.cetc.di.io.manager.FTPtoHDFSReturn@46c79a0c, except ng.IllegalStateException: Serialized class com.cetc.di.io.manager.FTPtoHDFSReturn must implement java.io.Serializable
at .caucho.hessian.io.SerializerFactory.getDefaultSerializer(SerializerFactory.java:261)
at .caucho.hessian.io.SerializerFactory.getSerializer(SerializerFactory.java:233)
at .caucho.hessian.io.Hessian2Output.writeObject(Hessian2Output.java:406)
at mon.serialize.support.hessian.Hessian2ObjectOutput.writeObject(Hessian2ObjectOutput.java:92)
at com.alibaba.dubbo.rpc.protocol.dubbo.DubboCodec.encodeResponseData(DubboCodec.java:200)
at com.alibaba.dubbo.remoting.exchange.codec.ExchangeCodec.encodeResponse(ExchangeCodec.java:273)
at com.alibaba.dubbo.remoting.exchange.codec.ExchangeCodec.encode(ExchangeCodec.java:77)
at com.alibaba.dubbo.rpc.protocol.dubbo.DubboCountCodec.encode(DubboCountCodec.java:41)
at tyCodecAdapter$InternalEncoder.encode(NettyCodecAdapter.java:82)
at ty.handler.codec.oneone.OneToOneEncoder.doEncode(OneToOneEncoder.java:66)
at ty.handler.codec.oneone.OneToOneEncoder.handleDownstream(OneToOneEncoder.java:59)
at ty.channel.DefaultChannelPipeline.sendDownstream(DefaultChannelPipeline.java:591)
at ty.channel.DefaultChannelPipeline$DefaultChannelHandlerContext.sendDownstream(DefaultChannelPipeline.java:784)
at ty.channel.SimpleChannelHandler.writeRequested(SimpleChannelHandler.java:292)
at tyHandler.writeRequested(NettyHandler.java:99)
at ty.channel.SimpleChannelHandler.handleDownstream(SimpleChannelHandler.java:254)
at ty.channel.DefaultChannelPipeline.sendDownstream(DefaultChannelPipeline.java:591)
at ty.channel.DefaultChannelPipeline.sendDownstream(DefaultChannelPipeline.java:582)
at ty.channel.Channels.write(Channels.java:704)
at ty.channel.Channels.write(Channels.java:671)
at ty.channel.AbstractChannel.write(AbstractChannel.java:248)
at tyChannel.send(NettyChannel.java:98)
at com.alibaba.dubbo.remoting.transport.AbstractPeer.send(AbstractPeer.java:51)
at com.alibaba.dubbo.remoting.exchange.support.header.HeaderExchangeHandler.received(HeaderExchangeHandler.java:171)
at com.alibaba.dubbo.remoting.transport.DecodeHandler.received(DecodeHandler.java:52)
at com.alibaba.dubbo.remoting.transport.dispather.ChannelEventRunnable.run(ChannelEventRunnable.java:82)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
at ng.Thread.run(Thread.java:745)
at com.alibaba.dubbo.remoting.exchange.support.DefaultFuture.returnFromResponse(DefaultFuture.java:190)
at com.alibaba.dubbo.remoting.exchange.support.DefaultFuture.get(DefaultFuture.java:110)
at com.alibaba.dubbo.remoting.exchange.support.DefaultFuture.get(DefaultFuture.java:84)
at com.alibaba.dubbo.rpc.protocol.dubbo.DubboInvoker.doInvoke(DubboInvoker.java:96)
at com.alibaba.dubbo.rpc.protocol.AbstractInvoker.invoke(AbstractInvoker.java:144)
at com.alibaba.dubbo.rpc.listener.ListenerInvokerWrapper.invoke(ListenerInvokerWrapper.java:74)
at com.alibaba.dubbo.rpc.protocol.dubbo.filter.FutureFilter.invoke(FutureFilter.java:53)
at com.alibaba.dubbo.rpc.protocol.ProtocolFilterWrapper$1.invoke(ProtocolFilterWrapper.java:91)
at com.alibaba.dubbo.monitor.support.MonitorFilter.invoke(MonitorFilter.java:75)
at com.alibaba.dubbo.rpc.protocol.ProtocolFilterWrapper$1.invoke(ProtocolFilterWrapper.java:91)
at com.alibaba.dubbo.rpc.filter.ConsumerContextFilter.invoke(ConsumerContextFilter.java:48)
at com.alibaba.dubbo.rpc.protocol.ProtocolFilterWrapper$1.invoke(ProtocolFilterWrapper.java:91)
at com.alibaba.dubbo.rpc.protocol.InvokerWrapper.invoke(InvokerWrapper.java:53)
at com.alibaba.dubbo.rpc.cluster.support.FailoverClusterInvoker.doInvoke(FailoverClusterInvoker.java:77)
... 5 more
解决⽅案：。