Obtain session information from the logon process

private static final String loginUrl = "http://42.120.50.206/apr/login.php";private String sessionId;public boolean login(String username, String password) {                                                       Map<String, String> params = new HashMap<String, String>();        params.put("username", username);        params.put("password", password);                                                       HttpURLConnection connection = null;                                               try {            connection = doPost2(loginUrl, params);            if (connection == null) {                return false;            }                                                       String key = "";                                                       if (connection != null) {                for (int i = 1; (key = connection.getHeaderFieldKey(i)) != null; i++) {                    //System.out.println("key: " + key);                    if (key.equalsIgnoreCase("set-cookie")) {                        sessionId = connection.getHeaderField(key);                        sessionId = sessionId.substring(0, sessionId.indexOf(";"));                        //System.out.println("sessionId: " + sessionId);                    }                 }                                                               InputStream is = connection.getInputStream();                String result = getResult(is);                System.out.println("result: " + result);                                                               if (sessionId != null) {                    return true;                }            }        } catch (IOException e) {            e.printStackTrace();        } finally {            if (connection != null) {                connection.disconnect();            }          }                                               return false;    }

Public HttpURLConnection doPost2 (String urlStr, Map <String, String> params) throws IOException {StringBuilder sb = new StringBuilder (); for (Map. entry <String, String> param: params. entrySet () {sb. append (param. getKey ()). append ("= "). append (param. getValue ()). append ("&");} int len = sb. length (); if (len> 0) {sb. deleteCharAt (len-1);} String args = sb. toString (); // System. out. println ("args:" + Args); return doPost2 (urlStr, args);}/*** @ param args * @ throws IOException * @ throws UnsupportedEncodingException */public HttpURLConnection doPost2 (String urlStr, String args) throws IOException {URL url = null; try {url = new URL (urlStr);} catch (MalformedURLException e) {e. printStackTrace (); return null;} HttpURLConnection connection = (HttpURLConnection) url. openConnection (); // simulates the browser, Can have no connection. setRequestProperty ("User-Agent", "Mozilla/5.0 (X11; Linux i686; rv: 7.0.1) Gecko/20100101 Firefox/7.0.1"); // This line is critical, this line of connection is required for login. setInstanceFollowRedirects (false); connection. setConnectTimeout (10000);/*** then set the connection to the output mode. URLConnection is usually used as input, such as downloading a Web page. * By setting URLConnection as output, you can transmit data to your web page. How to do this: */connection. setDoOutput (true); // connection. setRequestMethod ("POST");/*** finally, to get OutputStream, put it in Writer and put it into POST information for simplicity, for example :... */OutputStreamWriter out = new OutputStreamWriter (connection. getOutputStream (), "UTF-8"); out. write (args); // transmits data to the page. The key to post! // Remember to clean up out. flush (); out. close (); return connection ;}

private static String getResult(InputStream is) throws IOException {    StringBuilder sb = new StringBuilder();                               BufferedReader br = new BufferedReader(new InputStreamReader(               is));                                  String line = null;    while ((line = br.readLine()) != null) {           sb.append(line).append("\r\n");       }                                  return sb.toString();}

This article is from "recalling the past ..." Blog, please be sure to keep this source http://memory.blog.51cto.com/6054201/1288701