我正在使用某些应用程序的API下载文档。 问题是，当我尝试解析inputStream时，它将引发响应代码409异常。 但是最大的问题是它有时会抛出此异常。 此异常的原因是什么？

这是我的代码；

URL url = new URL(urlStr);

HttpsURLConnection conn = (HttpsURLConnection) url.openConnection();

conn.setReadTimeout(10000);

conn.setConnectTimeout(15000);

conn.setRequestMethod("GET");

conn.setDoOutput(true);

conn.setDoInput(true);

conn.setUseCaches(false);

conn.setAllowUserInteraction(false);

if (conn != null) {

try {

InputStream inputStream = conn.getInputStream();//this line throws exception

MyXmlParser myXmlParser = new MyXmlParser();

MyClientData myClientData = myXmlParser.parseMyOutput(inputStream);

return myClientData;

} catch (IOException e) {

throw e;

}

}

这是我的XML解析器；

public class MyXmlParser {

private final JAXBContext myOutputContext;

private final XMLInputFactory xif;

public MyXmlParser() throws JAXBException {

xif = XMLInputFactory.newFactory();

xif.setProperty(XMLInputFactory.IS_SUPPORTING_EXTERNAL_ENTITIES, false);

xif.setProperty(XMLInputFactory.SUPPORT_DTD, false);

myOutputContext = JAXBContext.newInstance(MyClientData.class);

}

public MyClientData parseMyOutput(InputStream inputStream) throws JAXBException {

Unmarshaller jaxbUnmarshaller = myOutputContext.createUnmarshaller();

return (MyClientData) jaxbUnmarshaller.unmarshal(createStreamReader(inputStream));

}

private XMLStreamReader createStreamReader(InputStream inputStream) throws JAXBException {

try {

return xif.createXMLStreamReader(inputStream);

} catch (XMLStreamException ex) {

throw new JAXBException(ex);

}

}

}

这是从应用程序的API中获取的，用于下载文档；

HTTP Request GET /{file_id}/download

我遇到错误了；

java.io.IOException: Server returned HTTP response code: 409 for URL: https://5.5.5.5:443/4144444/download