如何检查通过HttpsURLConnection发送的HTTP请求标头？

Question

The simple Java code below works. Is there an easy way to find out / inspect the HTTP request (not the response) headers actually sent?

import java.net.URL;
import java.io.*;
import javax.net.ssl.HttpsURLConnection;

public class Test {
    public static void main(String[] args) throws Exception {
        String httpsURL = "https://api.gdax.com/products/BTC-USD/book?level=1";
        URL myurl = new URL(httpsURL);
        HttpsURLConnection con = (HttpsURLConnection) myurl.openConnection();
        InputStream ins = con.getInputStream();
        InputStreamReader isr = new InputStreamReader(ins);
        BufferedReader in = new BufferedReader(isr);

        String inputLine;

        while ((inputLine = in.readLine()) != null) {
            System.out.println(inputLine);
        }

        in.close();
    }
}

Answer 1

I think you can not do it programaticaly, you could use some kind of proxy like TCP/IP monitor in Eclipse. Or enable the debbug option for java adding these options:

-Djava.util.logging.config.file=logging.properties

And put in logging.properties (by default in JRE_HOME\\lib) the following property

sun.net.www.protocol.http.HttpsURLConnection.level = ALL