开发环境的Undertow下运行中发生这个错误，但进程未受影响：
- 2018-12-15 14:26:35
- [DEBUG]-[Thread: XNIO-1 task-21]-[io.undertow.servlet.spec.HttpServletResponseImpl.responseDone()]: UT005013: An IOException occurred
- java.io.IOException: 你的主机中的软件中止了一个已建立的连接。
- at sun.nio.ch.SocketDispatcher.write0(Native Method)
- at sun.nio.ch.SocketDispatcher.write(SocketDispatcher.java:51)
- at sun.nio.ch.IOUtil.writeFromNativeBuffer(IOUtil.java:93)
- at sun.nio.ch.IOUtil.write(IOUtil.java:65)
- at sun.nio.ch.SocketChannelImpl.write(SocketChannelImpl.java:471)
- at org.xnio.nio.NioSocketConduit.write(NioSocketConduit.java:164)
- at io.undertow.server.protocol.http.HttpResponseConduit.write(HttpResponseConduit.java:609)
- at io.undertow.conduits.ChunkedStreamSinkConduit.flush(ChunkedStreamSinkConduit.java:270)
- at org.xnio.conduits.ConduitStreamSinkChannel.flush(ConduitStreamSinkChannel.java:162)
- at io.undertow.channels.DetachableStreamSinkChannel.flush(DetachableStreamSinkChannel.java:119)
- at org.xnio.channels.Channels.flushBlocking(Channels.java:63)
- at io.undertow.servlet.spec.ServletOutputStreamImpl.close(ServletOutputStreamImpl.java:618)
- at io.undertow.servlet.spec.HttpServletResponseImpl.closeStreamAndWriter(HttpServletResponseImpl.java:486)
- at io.undertow.servlet.spec.HttpServletResponseImpl.responseDone(HttpServletResponseImpl.java:575)
- at io.undertow.servlet.handlers.ServletInitialHandler.handleFirstRequest(ServletInitialHandler.java:346)
- at io.undertow.servlet.handlers.ServletInitialHandler.access$100(ServletInitialHandler.java:81)
- at io.undertow.servlet.handlers.ServletInitialHandler$2.call(ServletInitialHandler.java:138)
- at io.undertow.servlet.handlers.ServletInitialHandler$2.call(ServletInitialHandler.java:135)
- at io.undertow.servlet.core.ServletRequestContextThreadSetupAction$1.call(ServletRequestContextThreadSetupAction.java:48)
- at io.undertow.servlet.core.ContextClassLoaderSetupAction$1.call(ContextClassLoaderSetupAction.java:43)
- at io.undertow.servlet.handlers.ServletInitialHandler.dispatchRequest(ServletInitialHandler.java:272)
- at io.undertow.servlet.handlers.ServletInitialHandler.access$000(ServletInitialHandler.java:81)
- at io.undertow.servlet.handlers.ServletInitialHandler$1.handleRequest(ServletInitialHandler.java:104)
- at io.undertow.server.Connectors.executeRootHandler(Connectors.java:360)
- at io.undertow.server.HttpServerExchange$1.run(HttpServerExchange.java:830)
- at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
- at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
- at java.lang.Thread.run(Thread.java:745)
是否没什么关系？
项目：JFinal
这个是 debug 信息，不算错误。 原因主要有两种：
1：客户端在发请求的时候，当前请求还没完事，就断开连接，这种你无法控制
2：下载文件的时候，下载到一半，客户不想下载了，中断了连接，这种事情都很常见