xml高手进入，如何将Document对象变成String类型的xml呀

[meiscai]

ByteArrayOutputStream outStream = new ByteArrayOutputStream();
//OutputStream outStream = new OutputStream();
OutputStreamWriter outWriter = new OutputStreamWriter(outStream);
((XmlDocument)doc).write(outWriter, "GB2312");

String str = outStream.toString();

这样到write的时候就异常了。

[wqsea]

Document rootDocument = new Document(rootElement);
XMLOutputter XMLout = new XMLOutputter();
XMLout.setEncoding("UTF-8");
XMLout.setNewlines(true);
XMLout.setIndent(true);
mqString = XMLout.outputString(rootDocument);

[whyxx]

outputString

[xjdawu]

楼上用的是ora.jdom包，楼主用的是org.apache.crimson包，请问楼主是什么异常？