HttpURLConnection is subclass of URLConnection with support for HTTP-specific features, for example: open a connection, retrieve message and post data to server.
First of all, we need declare a global variable cookie:
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public static String cookie = null; |
Secondly, create a method GetCookieFromURL, open a URL connection, read the cookie from opened connection and assign to global variable cookie:
Please note the connection will be closed when method is finished(it’s one-off connection).
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public static String GetCookieFromURL() { String result = null; HttpURLConnection con = null; try { URL url = new URL(urlName); con = (HttpURLConnection) (url.openConnection()); con.setConnectTimeout(40000); con.setReadTimeout(40000); con.setRequestMethod("POST"); con.setRequestProperty("User-Agent", "Mozilla/4.0 (compatible; MSIE 6.0; Windows 2000)"); con.setFollowRedirects(true); con.setDoOutput(true); con.setDoInput(true); con.setUseCaches(false); con.setAllowUserInteraction(false); con.setRequestProperty("Content-Type", "application/x-www-form-urlencoded"); con.setRequestProperty("Content-Language", "en-US"); result = con.getHeaderField("Set-Cookie"); } catch (Exception e) { e.printStackTrace(); } finally { con.disconnect(); con = null; } return result; } |
Third, we will open a different HTTP connection with cookies we got previously, prior to opening collection, use urlConn.setRequestProperty set the cookie value, by this way, we are able to pass-by session across multiple requests, it’s very useful, for example, after login, we need use login session for a while to read and modify data.
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public static byte[] getByteFromFile(String urlName) throws AvException { InputStream input = null; HttpURLConnection urlConn = null; try { urlConn = (HttpURLConnection) (new URL(urlName).openConnection()); urlConn.setRequestMethod("POST"); urlConn.setRequestProperty("User-Agent", "Mozilla/4.0 (compatible; MSIE 6.0; Windows 2000)"); urlConn.setFollowRedirects(true); urlConn.setDoOutput(true); urlConn.setDoInput(true); urlConn.setUseCaches(false); urlConn.setAllowUserInteraction(false); urlConn.setRequestProperty("Content-Type", "application/x-www-form-urlencoded"); urlConn.setRequestProperty("Content-Language", "en-US"); urlConn.setRequestProperty("Cookie", cookie); input = urlConn.getInputStream(); ByteArrayOutputStream baos = new ByteArrayOutputStream(); int bytesRead = 0; byte[] buffer = new byte[8192]; while ((bytesRead = input.read(buffer, 0, buffer.length)) != -1) { baos.write(buffer, 0, bytesRead); } return baos.toByteArray(); } catch (Exception e) { throw new AvException("maybe the internet is disable", AvException.Type.INTERNET_DENIED); } finally { urlConn.disconnect(); urlConn = null; } } |