HttpURLConnection Closing IO Streams

问题:

I am new to Java and HttpURLConnection. Should I close the opened IO streams before dropping the connection. If I close the streams, should I need to drop the connection as well? Which is the proper way of implementation?

try {
String uri = "http://localhost:8081/RESTEASY/saju/post/text";
URL url = new URL(uri);
connection =
    (HttpURLConnection) url.openConnection();
connection.setRequestMethod("POST");
connection.setRequestProperty("Accept", "text/plain");
connection.setRequestProperty("Content-Type", "text/plain");
connection.setDoOutput(true);

OutputStream os = connection.getOutputStream();

//bla bla

System.out.println(connection.getResponseCode());
InputStream iStream = connection.getInputStream();

//bla bla

} catch (MalformedURLException e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
} catch (IOException e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
}finally{
    // os.close(); - IS THIS REQUIRED
    // iStream.close(); - IS THIS REQUIRED
    connection.disconnect();    
}
}

回答1:

You should call close() on the input/output/error streams when you are finished using them.

Disconnect is more complicated. According to the javadoc for disconnect():

"Indicates that other requests to the server are unlikely in the near future."

This is recognizing the fact that HTTP 1.1 spec has a "persistent connection" feature that allows the same TCP/IP connection to be used in a sequence of requests to the same server. (This happens transparently.) When you call disconnect, it is likely to be taken as a hint to close the connection.

So from a resource and performance perspective:

• it is good idea to call disconnect if you aren't likely to send another request to the same server,
• it is a bad idea if another request is likely in the near future.