How to implement login in an Android application

Question

I'm a beginner and I just can't find a solution that would work.

What I want to do: User types in username and password, and the application logs in to a website. If the login is unsuccessful it returns false and a proper message, otherwise it returns true and proceeds to the next activity (gets another site, parses html, and displays content).

Where I'm stuck at: How to detect a successful login?

Here's my code

Relevant code from LoginActivity:

    Authentication auth = new Authentication();                     
    boolean loginSuccess = auth.authenticateUser(username, pass);

    if (!loginSuccess) {
        Toast.makeText(getBaseContext(), 
                "Invalid username or password.", 
                Toast.LENGTH_SHORT).show();                                                 
    }

    else {
        Intent intent = new Intent(LoginActivity.this, MenuActivity.class);
        LoginActivity.this.startActivity(intent);
    }

Method from Authentication class:

public boolean authenticateUser(String username, String pass) {

boolean loginSuccess = false;       
HttpRequest httpRequest = new HttpRequest();        
String result = "";

try {           
    result = httpRequest.getResult(username, pass);
    Log.d("RESULT", result);            

        // Checking if it was a successful login    
    if (**SOMETHING**) loginSuccess = true;         
    } catch (ParseException e) {            
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    }           

return loginSuccess;                
}

Since I get 200 (OK) status, I think the code for POST works ok, so I won't put the whole HttpRequest class here, just the most important methods:

public String getResult(String username, String pass) throws ParseException, IOException {
    String result = "";
    response = postData(username, pass);
    entity = response.getEntity();
    if (entity != null) {
        result = EntityUtils.toString(response.getEntity());                    
    }   

    return result;
}       

public HttpResponse postData(String username, String password) throws ClientProtocolException, IOException {
    HttpPost httpPost = getHttpPost(username, password);            
    HttpClient httpClient = getHttpClient();
    return httpClient.execute(httpPost);                
}

private HttpPost getHttpPost(String username, String password) throws UnsupportedEncodingException {
    String url = "https://www.sitename.com/login.aspx";
    HttpPost httpPost = new HttpPost(url);      

    List<NameValuePair> parameters = new ArrayList<NameValuePair>(2);
    parameters.add(new BasicNameValuePair("txtUsername", username));
    parameters.add(new BasicNameValuePair("txtPassword", password));                
    httpPost.setEntity(new UrlEncodedFormEntity(parameters));

    return httpPost;        
}

So, what I'm missing is part of the code from Authentication class, where I need to see if it was a successful login. I don't know what to do with result variable that I got (or response, or entity).

score 0 · Answer 1 · edited Jun 06 '17 at 09:10

0

I think 200 (OK) status is sufficient to say that the login is successful. Otherwise, you should get 401 denied status code. Please see this question RESTful Login Failure: Return 401 or Custom Response. You might modify the getResult to return Boolean and change your getResult to return true if the status is ok.

edited Jun 06 '17 at 09:10

Felix

571
14
34

answered Sep 10 '12 at 22:54

patrick

138
1
7

The thing is I checked the status both for invalid and valid login data, and it returned the same 200 code (I will recheck, but I'm pretty sure I didn't make some mistake). Also, I tried typing correct username and pass and then fetching the next web site, but all I got was the same login page (though that might have something to do with cookies?) – dronevil Sep 11 '12 at 13:58
Yes I checked, 200 status is not enough, since I get it for invalid username and password. Any other suggestions? I have no idea. I tried reading response content, but all I get is some html and css, with nothing that would indicate login status. – dronevil Sep 11 '12 at 19:13

How to implement login in an Android application

1 Answers1

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