dom4j 输出UTF-8 XML时中文乱码

使用DOM4J的XMLWriter输出UTF-8编码的XML文件时，出现乱码。 

 XMLWriter xmlWriter = null;
  try {
   FileWriter fw = new FileWriter("message.xml");
   OutputFormat outFormat = OutputFormat.createPrettyPrint();
   outFormat.setEncoding("UTF-8");
   outFormat.setTrimText(false);
   xmlWriter= new XMLWriter(fw,outFormat);
   xmlWriter.write(doc);
   
  } catch (IOException e) {
   e.printStackTrace();
  }finally{
   if(xmlWriter!=null)
    xmlWriter.close();
  }
doc如果含有中文，会出现乱码的问题，将上面的FileWriter改成FileOutputStream便可以了。

XMLWriter xmlWriter = null;
  try {
   OutputFormat outFormat = OutputFormat.createPrettyPrint();
   outFormat.setEncoding("UTF-8");
   outFormat.setTrimText(false);
   xmlWriter= new XMLWriter(new FileOutputStream("message.xml"),outFormat);
   xmlWriter.write(doc);
   
  } catch (IOException e) {
   e.printStackTrace();
  }finally{
   if(xmlWriter!=null)
    xmlWriter.close();
  }