您好，我的java服务器连接用户遇到此问题。
如何解决此问题？服务器是linux centos 7
服务器具有2 GB内存和2个核心2500MHz
Caused by: org.xml.sax.SAXParseException: Document root element is missing.
at org.apache.crimson.parser.Parser2.fatal(Parser2.java:3182)
at org.apache.crimson.parser.Parser2.fatal(Parser2.java:3170)
at org.apache.crimson.parser.Parser2.parseInternal(Parser2.java:501)
at org.apache.crimson.parser.Parser2.parse(Parser2.java:305)
at org.apache.crimson.parser.XMLReaderImpl.parse(XMLReaderImpl.java:442)
at org.jdom.input.SAXBuilder.build(SAXBuilder.java:453)
at org.jdom.input.SAXBuilder.build(SAXBuilder.java:770)
at jQ.a(Unknown Source)
at bp.a(Unknown Source)
at kw.decode(Unknown Source)
at org.jboss.netty.handler.codec.oneone.OneToOneDecoder.handleUpstream(OneToOneDecoder.java:67)
at org.jboss.netty.channel.DefaultChannelPipeline.sendUpstream(DefaultChannelPipeline.java:564)
at org.jboss.netty.channel.DefaultChannelPipeline$DefaultChannelHandlerContext.sendUpstream(DefaultChannelPipeline.java:792)
at org.jboss.netty.channel.Channels.fireMessageReceived(Channels.java:296)
at org.jboss.netty.handler.codec.frame.FrameDecoder.unfoldAndFireMessageReceived(FrameDecoder.java:352)
at org.jboss.netty.handler.codec.frame.FrameDecoder.callDecode(FrameDecoder.java:334)
at org.jboss.netty.handler.codec.frame.FrameDecoder.messageReceived(FrameDecoder.java:207)
at org.jboss.netty.channel.SimpleChannelUpstreamHandler.handleUpstream(SimpleChannelUpstreamHandler.java:75)
at org.jboss.netty.channel.DefaultChannelPipeline.sendUpstream(DefaultChannelPipeline.java:564)
at org.jboss.netty.channel.DefaultChannelPipeline.sendUpstream(DefaultChannelPipeline.java:559)
at org.jboss.netty.channel.Channels.fireMessageReceived(Channels.java:268)
at org.jboss.netty.channel.Channels.fireMessageReceived(Channels.java:255)
at org.jboss.netty.channel.socket.nio.NioWorker.read(NioWorker.java:94)
at org.jboss.netty.channel.socket.nio.AbstractNioWorker.processSelectedKeys(AbstractNioWorker.java:372)
at org.jboss.netty.channel.socket.nio.AbstractNioWorker.run(AbstractNioWorker.java:246)
at org.jboss.netty.channel.socket.nio.NioWorker.run(NioWorker.java:38)
at org.jboss.netty.util.ThreadRenamingRunnable.run(ThreadRenamingRunnable.java:102)
at org.jboss.netty.util.internal.DeadLockProofWorker$1.run(DeadLockProofWorker.java:42)
at org.jboss.netty.handler.execution.MemoryAwareThreadPoolExecutor$MemoryAwareRunnable.run(MemoryAwareThreadPoolExecutor.java:613)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)