读取XML文件时出现异常，Connection reset Nested exception: Connection reset

在程序里执行到这句时
Document document = reader.read(new File(fileName));
出现下面异常，请帮忙，是何故？ 非常感谢org.dom4j.DocumentException: Connection reset Nested exception: Connection reset
at org.dom4j.io.SAXReader.read(SAXReader.java:484)
at org.dom4j.io.SAXReader.read(SAXReader.java:365)
at app.XMLSample.modifyDocument(XMLSample.java:103)
at app.XMLSample.main(XMLSample.java:28)
Nested exception: 
java.net.SocketException: Connection reset
at java.net.SocketInputStream.read(SocketInputStream.java:168)
at java.io.BufferedInputStream.fill(BufferedInputStream.java:218)
at java.io.BufferedInputStream.read(BufferedInputStream.java:235)
at sun.net.TransferProtocolClient.readServerResponse(TransferProtocolClient.java:49)
at sun.net.ftp.FtpClient.readReply(FtpClient.java:217)
at sun.net.ftp.FtpClient.openServer(FtpClient.java:489)
at sun.net.ftp.FtpClient.openServer(FtpClient.java:475)
at sun.net.www.protocol.ftp.FtpURLConnection.connect(FtpURLConnection.java:270)
at sun.net.www.protocol.ftp.FtpURLConnection.getInputStream(FtpURLConnection.java:352)
at org.apache.xerces.impl.XMLEntityManager.setupCurrentEntity(Unknown Source)
at org.apache.xerces.impl.XMLEntityManager.startEntity(Unknown Source)
at org.apache.xerces.impl.XMLEntityManager.startDTDEntity(Unknown Source)
at org.apache.xerces.impl.XMLDTDScannerImpl.setInputSource(Unknown Source)
at org.apache.xerces.impl.XMLDocumentScannerImpl$DTDDispatcher.dispatch(Unknown Source)
at org.apache.xerces.impl.XMLDocumentFragmentScannerImpl.scanDocument(Unknown Source)
at org.apache.xerces.parsers.XML11Configuration.parse(Unknown Source)
at org.apache.xerces.parsers.XML11Configuration.parse(Unknown Source)
at org.apache.xerces.parsers.XMLParser.parse(Unknown Source)
at org.apache.xerces.parsers.AbstractSAXParser.parse(Unknown Source)
at org.dom4j.io.SAXReader.read(SAXReader.java:465)
at org.dom4j.io.SAXReader.read(SAXReader.java:365)
at app.XMLSample.modifyDocument(XMLSample.java:103)
at app.XMLSample.main(XMLSample.java:28)
Nested exception: java.net.SocketException: Connection reset
at java.net.SocketInputStream.read(SocketInputStream.java:168)
at java.io.BufferedInputStream.fill(BufferedInputStream.java:218)
at java.io.BufferedInputStream.read(BufferedInputStream.java:235)
at sun.net.TransferProtocolClient.readServerResponse(TransferProtocolClient.java:49)
at sun.net.ftp.FtpClient.readReply(FtpClient.java:217)
at sun.net.ftp.FtpClient.openServer(FtpClient.java:489)
at sun.net.ftp.FtpClient.openServer(FtpClient.java:475)
at sun.net.www.protocol.ftp.FtpURLConnection.connect(FtpURLConnection.java:270)
at sun.net.www.protocol.ftp.FtpURLConnection.getInputStream(FtpURLConnection.java:352)
at org.apache.xerces.impl.XMLEntityManager.setupCurrentEntity(Unknown Source)
at org.apache.xerces.impl.XMLEntityManager.startEntity(Unknown Source)
at org.apache.xerces.impl.XMLEntityManager.startDTDEntity(Unknown Source)
at org.apache.xerces.impl.XMLDTDScannerImpl.setInputSource(Unknown Source)
at org.apache.xerces.impl.XMLDocumentScannerImpl$DTDDispatcher.dispatch(Unknown Source)
at org.apache.xerces.impl.XMLDocumentFragmentScannerImpl.scanDocument(Unknown Source)
at org.apache.xerces.parsers.XML11Configuration.parse(Unknown Source)
at org.apache.xerces.parsers.XML11Configuration.parse(Unknown Source)
at org.apache.xerces.parsers.XMLParser.parse(Unknown Source)
at org.apache.xerces.parsers.AbstractSAXParser.parse(Unknown Source)
at org.dom4j.io.SAXReader.read(SAXReader.java:465)
at org.dom4j.io.SAXReader.read(SAXReader.java:365)
at app.XMLSample.modifyDocument(XMLSample.java:103)
at app.XMLSample.main(XMLSample.java:28)