URL url = new URL("http://www.example.com/comment");
HttpURLConnection connection = (HttpURLConnection) url.openConnection();
connection.setDoOutput(true);
connection.setRequestMethod("POST");
Is
connection.setRequestProperty(key, value);
the same as
OutputStreamWriter writer = new OutputStreamWriter(connection.getOutputStream());
writer.write("key=" + value);
writer.close();
?
If not, please correct me.
No, it is not. The URLConnection#setRequestProperty() sets a request header. For HTTP requests you can find all possible headers here.
The writer just writes the request body. In case of POST with urlencoded content, you'd normally write the query string into the request body instead of appending it to the request URI like as in GET.
That said, connection.setDoOutput(true); already implicitly sets the request method to POST in case of a HTTP URI (because it's implicitly required to write to the request body then), so doing an connection.setRequestMethod("POST"); afterwards is unnecessary.
来源：https://stackoverflow.com/questions/2560150/connection-setrequestproperty-and-excplicitly-writing-to-the-urloutputstream-are