1. public class AutomaticLogin {
2.  
3.     private List<String> cookies;
4.     private HttpsURLConnection conn;
5.  
6.     private final String USER_AGENT = "Mozilla/5.0 (Windows NT 6.1; Win64; x64; rv:25.0) Gecko/20100101 Firefox/25.0";
7.  
8.     public static void main(String[] args) throws Exception {
9.  
10.         String url = "https://accounts.craigslist.org/login";
11.         String gmail = "https://accounts.craigslist.org/login/home?show_tab=postings";
12.  
13.  
14.         AutomaticLogin http = new AutomaticLogin();
15.  
16.  
17.         CookieHandler.setDefault(new CookieManager());
18.  
19.         String page = http.GetPageContent(url);
20.  
21.         String postParams = http.getFormParams(page, "username", "password");
22.  
23.         String anotherString = null;
24.         anotherString = postParams.substring(0, 93);
25.  
26.         System.out.println(postParams);
27.         System.out.println();
28.  
29.  
30.         http.sendPost(url, postParams);
31.  
32.         String result = http.GetPageContent(gmail);
33.         System.out.println(result);
34.  
35.     }
36.  
37.     private void sendPost(String url, String postParams) throws Exception {
38.  
39.         URL obj = new URL(url);
40.         conn = (HttpsURLConnection) obj.openConnection();
41.  
42.  
43.  
44.         conn.setUseCaches(false);
45.         conn.setRequestMethod("POST");
46.         conn.setRequestProperty("Host", "craigslist.org");
47.         conn.setRequestProperty("User-Agent", USER_AGENT);
48.         conn.setRequestProperty("Accept","text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8");
49.         conn.setRequestProperty("Accept-Language", "en-US,en;q=0.5");
50.         conn.setAllowUserInteraction(true);
51.  
52.         conn.setRequestProperty("Connection", "keep-alive");
53.         conn.setRequestProperty("Referer", "https://accounts.craigslist.org/login/home");
54.         conn.setRequestProperty("Content-Type", "x-www-form-urlencoded");
55.  
56.         conn.setFixedLengthStreamingMode(postParams.getBytes().length);
57.  
58.         conn.setInstanceFollowRedirects(false);
59.  
60.         conn.setDoOutput(true);
61.         conn.setDoInput(true);
62.         if (cookies != null) {
63.             for (String cookie : this.cookies) {
64.                 conn.addRequestProperty("Cookie", cookie.split(" ", 2)[0]);
65.             }
66.         }
67.  
68.  
69.         DataOutputStream wr = new DataOutputStream(conn.getOutputStream());
70.         wr.writeBytes(postParams);
71.         wr.flush();
72.         wr.close();
73.  
74.         int responseCode = conn.getResponseCode();
75.         String msg = conn.getResponseMessage();
76.         System.out.println("\nSending 'POST' request to URL : " + url);
77.         System.out.println("Post parameters : " + postParams);
78.         System.out.println("Response Code : " + responseCode);
79.         System.out.println(msg);
80.  
81.  
82.         BufferedReader in =
83.                 new BufferedReader(new InputStreamReader(conn.getInputStream()));
84.         String inputLine;
85.         StringBuffer response = new StringBuffer();
86.  
87.         while ((inputLine = in.readLine()) != null) {
88.             response.append(inputLine);
89.  
90.  
91.         }
92.         in.close();
93.         System.out.println(response.toString());
94.  
95.     }
96.  
97.     private String GetPageContent(String url) throws UnexpectedException, Exception  {
98.  
99.         URL obj = new URL(url);
100.         conn = (HttpsURLConnection) obj.openConnection();
101.  
102.         conn.setRequestMethod("GET");
103.  
104.         conn.setUseCaches(false);
105.  
106.         // act like a browser
107.         conn.setRequestProperty("User-Agent", USER_AGENT);
108.         conn.setRequestProperty("Accept","text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8");
109.         conn.setRequestProperty("Accept-Language", "en-US,en;q=0.5");
110.         if (cookies != null) {
111.             for (String cookie : this.cookies) {
112.                 conn.addRequestProperty("Cookie", cookie.split(" ", 1)[0]);
113.             }
114.         }
115.         int responseCode = conn.getResponseCode();
116.         String msg = conn.getResponseMessage();
117.         System.out.println("\nSending 'GET' request to URL : " + url);
118.         System.out.println("Response Code : " + responseCode);
119.         System.out.println(msg);
120.  
121.         BufferedReader in =
122.                 new BufferedReader(new InputStreamReader(conn.getInputStream()));
123.         String inputLine;
124.         StringBuffer response = new StringBuffer();
125.  
126.  
127.         while ((inputLine = in.readLine()) != null) {
128.             response.append(inputLine);
129.         }
130.  
131.         in.close();
132.  
133.         // Get the response cookies
134.  
135.         setCookies(conn.getHeaderFields().get("Set-Cookie"));
136.  
137.         return response.toString();
138.  
139.     }
140.  
141.     public String getFormParams(String html, String username, String password)
142.             throws UnsupportedEncodingException {
143.  
144.         System.out.println("Extracting form's data...");
145.  
146.         Document doc = Jsoup.parse(html);
147.  
148.         // Google form id
149.         Element loginform = doc.getElementById("pagecontainer");
150.         Elements inputElements = loginform.getElementsByTag("input");
151.         int count = 0;
152.         List<String> paramList = new ArrayList<String>();
153.         for (Element inputElement : inputElements) {
154.             String key = inputElement.attr("name");
155.             String value = inputElement.attr("value");
156.  
157.             if(key.equals("emailAddress"))
158.                 break;
159.             if (key.equals("inputEmailHandle"))
160.                 value = username;
161.             else if (key.equals("inputPassword"))
162.                 value = password;
163.  
164.             paramList.add(key + "=" + URLEncoder.encode(value, "UTF-8"));
165.         }
166.  
167.  
168.         // build parameters list
169.         StringBuilder result = new StringBuilder();
170.  
171.         for (String param : paramList) {
172.  
173.             if (result.length() == 0) {
174.                 result.append(param);
175.             } else {
176.                 result.append("&" + param);
177.             }
178.         }
179.         return result.toString();
180.     }
181.     public List<String> getCookies() {
182.         return cookies;
183.     }
184.     public void setCookies(List<String> cookies) {
185.         this.cookies = cookies;
186.     }
187. }