Jsoup Logging into websites with Jsoup A more comprehensive authentication POST request with Jsoup

Example

Most websites require a much more complicated process than the one demonstrated above.

Common steps for logging into a website are:

1. Get the unique cookie from the initial login form.
2. Inspect the login form to see what the destination url is for the authentication request
3. Parse the login form to check for any security token that needs to be sent along with username and password.
4. Send the request.

Below is an example request that will log you into the GitHub website

// # Constants used in this example
final String USER_AGENT = "Mozilla/5.0 (Windows NT 10.0; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/51.0.2704.103 Safari/537.36"; 
final String LOGIN_FORM_URL = "https://github.com/login";  
final String LOGIN_ACTION_URL = "https://github.com/session";  
final String USERNAME = "yourUsername";  
final String PASSWORD = "yourPassword";  

// # Go to login page and grab cookies sent by server
Connection.Response loginForm = Jsoup.connect(LOGIN_FORM_URL)
                                     .method(Connection.Method.GET)
                                     .userAgent(USER_AGENT)
                                     .execute();  
Document loginDoc = loginForm.parse(); // this is the document containing response html
HashMap<String, String> cookies = new HashMap<>(loginForm.cookies()); // save the cookies to be passed on to next request  

// # Prepare login credentials 
String authToken = loginDoc.select("#login > form > div:nth-child(1) > input[type=\"hidden\"]:nth-child(2)")  
                           .first()  
                           .attr("value");  

HashMap<String, String> formData = new HashMap<>();
formData.put("commit", "Sign in");  
formData.put("utf8", "e2 9c 93");  
formData.put("login", USERNAME);  
formData.put("password", PASSWORD);  
formData.put("authenticity_token", authToken);  

// # Now send the form for login
Connection.Response homePage = Jsoup.connect(LOGIN_ACTION_URL)  
     .cookies(cookies)  
     .data(formData)  
     .method(Connection.Method.POST)  
     .userAgent(USER_AGENT)  
     .execute();

System.out.println(homePage.parse().html());