java HttpUrlConnection POST：需要请求提交POST的响应吗？

Question

I'm trying to post data on a server using java HttpUrlConnection class. It seems that if I somehow read the response of the server, the post works fine, but if I don't, the information is never posted.

This kind of behaviour is not mentionned in the HttpUrlConnection doc and all examples I've seen of HttUrlConnection ask for a response from the server.

I want to know if I made a mistake in my code or if this is a normal behaviour of HttpUrlConnection, and if it's the case, can someone with a better understanding of how this class works explain to me why it's so?

Thanks a lot!

Here is the code, the commented line is the one that makes the POST either work or fail:

URL url=new URL("myUrl");
HttpURLConnection connection = (HttpURLConnection) url.openConnection();
connection.setRequestMethod("POST");
connection.setRequestProperty("Content-Type", "application/x-www-form-urlencoded;charset=utf-8");
connection.setRequestProperty("Host", "myHost");
connection.setDoOutput(true);
os.write(staffToPost.getBytes("utf-8"));
os.flush();
os.close();
//System.out.println(connection.getResponseCode()+" "+connection.getResponseMessage());

Answer 1

URLCOnnection类需要完全握手才能发生POST。这意味着，一旦打开连接，就必须回读POST实际发生的响应。

Answer 2

You can explicitly call URLConnection.connect() or get any information about the HTTP response such as HttpURLConnection.getResponseCode etc to trigger HTTP request.

You should go through this comprehensive post on How to use java.net.URLConnection to fire and handle HTTP requests for better understanding.