出现错误--文件提前结束

package com.imooc.dom4j;

import java.io.FileOutputStream;
import java.io.OutputStreamWriter;
import java.io.Writer;
import java.util.List;

import org.dom4j.Document;
import org.dom4j.DocumentException;
import org.dom4j.Element;
import org.dom4j.io.SAXReader;

public class HrWrite {
     public void writeXml() {
      String file = "e:/xml/src/hr.xml";
      SAXReader reader =new SAXReader();
      try {
   Document document = reader.read(file);
   Element root = document.getRootElement();
   Element employee = root.addElement("employee");
   employee.addAttribute("num","311");
   employee.addElement("name").setText("李铁娃");
   employee.addElement("age").setText("55");
   employee.addElement("salary").setText("6000");
   Element apartment = employee.addElement("apartment");
   apartment.addElement("apartment-name").setText("人事部");
   apartment.addElement("address").setText("光腚大厦");
   Writer writer = new OutputStreamWriter(new FileOutputStream(file),"UTF-8");
   document.write(writer);
  } catch (Exception e) {
   // TODO Auto-generated catch block
   e.printStackTrace();
  }
     }
     public static void main(String[] args) {
   // TODO Auto-generated method stub
         HrWrite hrr = new HrWrite();
         hrr.writeXml();
  }
}

运行之后，原hr.xml文件成一片空白出现下列错误提示。

org.dom4j.DocumentException: Error on line 1 of document file:///e:/xml/src/hr.xml : 文件提前结束。
 at org.dom4j.io.SAXReader.read(SAXReader.java:462)
 at org.dom4j.io.SAXReader.read(SAXReader.java:303)
 at com.imooc.dom4j.HrWrite.writeXml(HrWrite.java:18)
 at com.imooc.dom4j.HrWrite.main(HrWrite.java:38)
Caused by: org.xml.sax.SAXParseException; systemId: file:///e:/xml/src/hr.xml; lineNumber: 1; columnNumber: 1; 文件提前结束。
 at com.sun.org.apache.xerces.internal.util.ErrorHandlerWrapper.createSAXParseException(Unknown Source)
 at com.sun.org.apache.xerces.internal.util.ErrorHandlerWrapper.fatalError(Unknown Source)
 at com.sun.org.apache.xerces.internal.impl.XMLErrorReporter.reportError(Unknown Source)
 at com.sun.org.apache.xerces.internal.impl.XMLErrorReporter.reportError(Unknown Source)
 at com.sun.org.apache.xerces.internal.impl.XMLScanner.reportFatalError(Unknown Source)
 at com.sun.org.apache.xerces.internal.impl.XMLDocumentScannerImpl$PrologDriver.next(Unknown Source)
 at com.sun.org.apache.xerces.internal.impl.XMLDocumentScannerImpl.next(Unknown Source)
 at com.sun.org.apache.xerces.internal.impl.XMLNSDocumentScannerImpl.next(Unknown Source)
 at com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl.scanDocument(Unknown Source)
 at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(Unknown Source)
 at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(Unknown Source)
 at com.sun.org.apache.xerces.internal.parsers.XMLParser.parse(Unknown Source)
 at com.sun.org.apache.xerces.internal.parsers.AbstractSAXParser.parse(Unknown Source)
 at com.sun.org.apache.xerces.internal.jaxp.SAXParserImpl$JAXPSAXParser.parse(Unknown Source)
 at org.dom4j.io.SAXReader.read(SAXReader.java:445)
 ... 3 more