The getHeaderField()
method doesn't work for me
You're asking this in the context of java.net.URLConnection
, is it? No, obtaining the raw HTTP response headers is not possible with URLconnection
. You'll need to fall back to low-level Socket programming. Here's an SSCCE, just copy'n'paste'n'run it.
package com.stackoverflow.q2307291;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.net.Socket;
public class Test {
public static void main(String[] args) throws IOException {
String hostname = "stackoverflow.com";
int port = 80;
Socket socket = null;
PrintWriter writer = null;
BufferedReader reader = null;
try {
socket = new Socket(hostname, port);
writer = new PrintWriter(new OutputStreamWriter(socket.getOutputStream()));
writer.println("GET / HTTP/1.1");
writer.println("Host: " + hostname);
writer.println("Accept: */*");
writer.println("User-Agent: Java"); // Be honest.
writer.println(""); // Important, else the server will expect that there's more into the request.
writer.flush();
reader = new BufferedReader(new InputStreamReader(socket.getInputStream()));
for (String line; (line = reader.readLine()) != null;) {
if (line.isEmpty()) break; // Stop when headers are completed. We're not interested in all the HTML.
System.out.println(line);
}
} finally {
if (reader != null) try { reader.close(); } catch (IOException logOrIgnore) {}
if (writer != null) { writer.close(); }
if (socket != null) try { socket.close(); } catch (IOException logOrIgnore) {}
}
}
}
To avoid SO being overloaded by everyone trying this snippet, here's how the output will look like:
HTTP/1.1 200 OK
Cache-Control: private
Content-Type: text/html; charset=utf-8
Expires: Sun, 21 Feb 2010 20:39:08 GMT
Server: Microsoft-IIS/7.5
Date: Sun, 21 Feb 2010 20:39:07 GMT
Connection: close
Content-Length: 208969
To learn more about sending HTTP requests the low-level way, read the HTTP specification.
However, you probably want to make use of getHeaderFields()
method instead to retrieve a header with multiple values. The getHeaderField()
namely only returns the last value, as per the linked API doc.
List<String> cookies = connection.getHeaderFields().get("Set-Cookie");
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