来自HttpURLConnection的InputStream：何时断开连接？

Question

The following constructor method should read an XML from an URL into a XML Document object. While it already works, I still doubt it is correct.

// Basic constructor method without exception handling
Feed(URL url) throws IOException, ParserConfigurationException, SAXException {
    HttpURLConnection httpcon = (HttpURLConnection) url.openConnection();
    httpcon.addRequestProperty("User-Agent", "Some User-Agent");

    InputStream inStream = httpcon.getInputStream();

    httpcon.disconnect();

    DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
    DocumentBuilder builder = factory.newDocumentBuilder();
    doc = builder.parse(inStream);
}

Questions:

• Shouldn't one first parse the InputStream and then close the HttpURLConnection ?
• Shouldn't there be a httpcon.connect() before I try to get something from httpcon ?

Answer 1

Shouldn't one first parse the InputStream and then close the HttpURLConnection?

Yes, or rather close the InputStream.

Shouldn't there be a http on.connect() before I try to get something from httpcon?

No. It's implicit in getting the input stream.

The code you posted is incorrect and should not work. The input stream should be read before the disconnect. Actually the disconnect is only necessary if you want o prevent connection pooling.