Develop Reference

Android Login with HTTP post, get results

I am trying to create a Login function so i can verify the users. I pass the Username , Password variables to AsyncTask class but i don't know hot to get results in order to use them. Any help? (I am posting part of the source code due to website restrictions)
btnLogin.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
if(txtUsername.getText().toString().trim().length() > 0 && txtPassword.getText().toString().trim().length() > 0)
{
// Retrieve the text entered from the EditText
String Username = txtUsername.getText().toString();
String Password = txtPassword.getText().toString();
/*Toast.makeText(MainActivity.this,
Username +" + " + Password+" \n Ready for step to post data", Toast.LENGTH_LONG).show();*/
String[] params = {Username, Password};
// we are going to use asynctask to prevent network on main thread exception
new PostDataAsyncTask().execute(params);
// Redirect to dashboard / home screen.
login.dismiss();
}
else
{
Toast.makeText(MainActivity.this,
"Please enter Username and Password", Toast.LENGTH_LONG).show();
}
}
});
Then i use the AsynkTask to do the check but do not know how to get the results and store them in a variable. Any help?
public class PostDataAsyncTask extends AsyncTask<String, String, String> {
protected void onPreExecute() {
super.onPreExecute();
// do stuff before posting data
}
#Override
protected String doInBackground(String... params) {
try {
// url where the data will be posted
String postReceiverUrl = "http://server.com/Json/login.php";
Log.v(TAG, "postURL: " + postReceiverUrl);
String line = null;
String fail = "notok";
// HttpClient
HttpClient httpClient = new DefaultHttpClient();
// post header
HttpPost httpPost = new HttpPost(postReceiverUrl);
// add your data
List<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>(2);
nameValuePairs.add(new BasicNameValuePair("UserName", params[0]));
nameValuePairs.add(new BasicNameValuePair("Password", params[1]));
httpPost.setEntity(new UrlEncodedFormEntity(nameValuePairs));
// execute HTTP post request
HttpResponse response = httpClient.execute(httpPost);
HttpEntity resEntity = response.getEntity();
line = resEntity.toString();
Log.v(TAG, "Testing response: " + line);
if (resEntity != null) {
String responseStr = EntityUtils.toString(resEntity).trim();
Log.v(TAG, "Response: " + responseStr);
Intent Hotels_btn_pressed = new Intent(MainActivity.this, Hotels.class);
startActivity(Hotels_btn_pressed);
// you can add an if statement here and do other actions based on the response
Toast.makeText(MainActivity.this,
"Error! User does not exist", Toast.LENGTH_LONG).show();
}else{
finish();
}
} catch (NullPointerException e) {
e.printStackTrace();
} catch (Exception e) {
e.printStackTrace();
}
return null;
}
#Override
protected void onPostExecute(String lenghtOfFile) {
// do stuff after posting data
}
}

Not the best code refactoring, but just to give you a hint.
I would create an interface (lets call it 'LogInListener'):
public interface LoginListener {
void onSuccessfulLogin(String response);
void onFailedLogin(String response);
}
The 'MainActivity' class would implement that interface and set itself as a listener the 'PostDataAsyncTask'. So, creating the async task from the main activity would look like this:
String[] params = {Username, Password};
// we are going to use asynctask to prevent network on main thread exception
PostDataAsyncTask postTask = new PostDataAsyncTask(this);
postTask.execute(params);
I would move 'PostDataAsyncTask' class into a new file:
public class PostDataAsyncTask extends AsyncTask<String, String, String> {
private static final String ERROR_RESPONSE = "notok";
private LoginListener listener = null;
public PostDataAsyncTask(LoginListener listener) {
this.listener = listener;
}
#Override
protected String doInBackground(String... params) {
String postResponse = "";
try {
// url where the data will be posted
String postReceiverUrl = "http://server.com/Json/login.php";
// HttpClient
HttpClient httpClient = new DefaultHttpClient();
// post header
HttpPost httpPost = new HttpPost(postReceiverUrl);
// add your data
List<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>(2);
nameValuePairs.add(new BasicNameValuePair("UserName", params[0]));
nameValuePairs.add(new BasicNameValuePair("Password", params[1]));
httpPost.setEntity(new UrlEncodedFormEntity(nameValuePairs));
// execute HTTP post request
HttpResponse response = httpClient.execute(httpPost);
HttpEntity resEntity = response.getEntity();
postResponse = EntityUtils.toString(resEntity).trim();
} catch (NullPointerException e) {
e.printStackTrace();
} catch (Exception e) {
e.printStackTrace();
}
return postResponse;
}
#Override
protected void onPostExecute(String postResponse) {
if (postResponse.isEmpty() || postResponse.equals(ERROR_RESPONSE) ) {
listener.onFailedLogin(postResponse);
} else {
listener.onSuccessfulLogin(postResponse);
}
}
}
So, 'doInBackground' returns the response to 'onPostExecute' (which runs on the UI thread), and 'onPostExecute' routes the result (success or failure) to the MainActivity, which implements the 'LogInListener' methods:
#Override
public void onSuccessfulLogin(String response) {
// you have access to the ui thread here - do whatever you want on suscess
// I'm just assuming that you'd like to start that activity
Intent Hotels_btn_pressed = new Intent(this, Hotels.class);
startActivity(Hotels_btn_pressed);
}
#Override
public void onFailedLogin(String response) {
Toast.makeText(MainActivity.this,
"Error! User does not exist", Toast.LENGTH_LONG).show();
}
I just assumed that that's what you wanted to do on success: start a new activity, and show a toast on fail.

Can't show Toast inside AsyncTask inside a DialogFragment

I'm using a DialogFragment to show a simple form, which then is posted to a remote server and a success/fail code is sent back.
However whenever I want to show a Toast when an error occurred I get an exception in which getActivity() returns null. Any idea why this is?
This is a summary of the code:
private class UploadNewGroupToServer extends AsyncTask<String, Void, Void>
{
ProgressDialog createGroupProgressDialog;
#Override
protected Void doInBackground(String... params)
{
getActivity().runOnUiThread(new Runnable()
{
public void run()
{
createGroupProgressDialog = new ProgressDialog(getActivity());
createGroupProgressDialog.setTitle("Creating group...");
createGroupProgressDialog.show();
}
});
String encodedImage = params[0];
String groupTitle = params[1];
String groupDesc = params[2];
//Create a new HttpClient and Post Header
HttpClient httpclient = new DefaultHttpClient();
HttpPost httppost = new HttpPost(URL_API_CREATE_GROUP);
try
{
// Add data
ArrayList<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>();
if(encodedImage != null)
{
nameValuePairs.add(new BasicNameValuePair("picture", encodedImage));
}
nameValuePairs.add(new BasicNameValuePair("title", groupTitle));
nameValuePairs.add(new BasicNameValuePair("desc", groupDesc));
nameValuePairs.add(new BasicNameValuePair("token", "MY_TOKEN_HERE!"));
httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs));
// Execute HTTP Post Request
ResponseHandler<String> responseHandler = new BasicResponseHandler();
Log.d("APP", "Going to execute ");
final String responseBody = httpclient.execute(httppost, responseHandler);
Log.d("APP", "Back from execute, responseBody is " + responseBody);
//More business logic here
// . . . . .
throw new Exception(); //simulate an error
} catch (final Exception e)
{
Log.d("APP", "Exception es " + e.getMessage());
createGroupProgressDialog.dismiss();
getActivity().runOnUiThread(new Runnable() //App dies here!
{
public void run()
{
Toast.makeText(getActivity(), "Error!", Toast.LENGTH_LONG).show();
}
});
}
return null;
}
Here's the logcat:
11-04 00:16:18.414: E/AndroidRuntime(7229): Caused by: java.lang.NullPointerException
11-04 00:16:18.414: E/AndroidRuntime(7229): at com.myapp.android.GroupCreateDialogFragment$UploadNewGroupToServer.doInBackground(GroupCreateDialogFragment.java:204)
11-04 00:16:18.414: E/AndroidRuntime(7229): at com.myapp.android.GroupCreateDialogFragment$UploadNewGroupToServer.doInBackground(GroupCreateDialogFragment.java:1)
11-04 00:16:18.414: E/AndroidRuntime(7229): at android.os.AsyncTask$2.call(AsyncTask.java:287)
11-04 00:16:18.414: E/AndroidRuntime(7229): at java.util.concurrent.FutureTask.run(FutureTask.java:234)
11-04 00:16:18.414: E/AndroidRuntime(7229): ... 4 more

When you invoke asynctask use
new UploadNewGroupToServer(getActivity()).execute();.
Now in the constructor
Context mContext;
pulic void UploadNewGroupToServer(Context context)
{
mContext = context;
}
Also move your progressdialog initialization to the constructor
pulic void UploadNewGroupToServer(Context context)
{
createGroupProgressDialog = new ProgressDialog(context);
createGroupProgressDialog.setTitle("Creating group...");
}
In onPreExecute
public void onPreExecute()
{
super.onPreExecute();
createGroupProgressDialog.show();
}
Also instead of displaying toast in doInbackground return result and in onPostExecute dismiss dialog and show toast accordingly.

Could your create a handler in your async task? If handler created in UI thread(If use MainLooper) post method samely runOnUiThread.
private class UploadNewGroupToServer extends AsyncTask<String, Void, Void>
{
ProgressDialog createGroupProgressDialog;
Handler handler;
protected void onPreExecute(){
handler = new Handler();
}
#Override
protected Void doInBackground(String... params)
{
handler.post(new Runnable()
{
public void run()
{
createGroupProgressDialog = new ProgressDialog(getActivity());
createGroupProgressDialog.setTitle("Creating group...");
createGroupProgressDialog.show();
}
});
String encodedImage = params[0];
String groupTitle = params[1];
String groupDesc = params[2];
//Create a new HttpClient and Post Header
HttpClient httpclient = new DefaultHttpClient();
HttpPost httppost = new HttpPost(URL_API_CREATE_GROUP);
try
{
// Add data
ArrayList<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>();
if(encodedImage != null)
{
nameValuePairs.add(new BasicNameValuePair("picture", encodedImage));
}
nameValuePairs.add(new BasicNameValuePair("title", groupTitle));
nameValuePairs.add(new BasicNameValuePair("desc", groupDesc));
nameValuePairs.add(new BasicNameValuePair("token", "MY_TOKEN_HERE!"));
httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs));
// Execute HTTP Post Request
ResponseHandler<String> responseHandler = new BasicResponseHandler();
Log.d("APP", "Going to execute ");
final String responseBody = httpclient.execute(httppost, responseHandler);
Log.d("APP", "Back from execute, responseBody is " + responseBody);
//More business logic here
// . . . . .
throw new Exception(); //simulate an error
} catch (final Exception e)
{
Log.d("APP", "Exception es " + e.getMessage());
createGroupProgressDialog.dismiss();
handler.post(new Runnable() //App dies here!
{
public void run()
{
Toast.makeText(getActivity(), "Error!", Toast.LENGTH_LONG).show();
}
});
}
return null;
}

Connecting and getting data through web API in android

Can anybody please help me with this one. I am trying to get information in a server through web API, I believe, in my code below that I can already connect to the server (because no error appear). But when I am trying to display information that that I get, it display null value. I'm not sure where a forgot something or if my way of parsing it is right.
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
buttonGetData = (Button) findViewById(R.id.buttonGetData);
editTextSearchString = (EditText) findViewById(R.id.editTextSearchString);
textViewFirstName = (TextView) findViewById(R.id.textViewFirstName);
textViewLastName = (TextView) findViewById(R.id.textViewLastName);
display = (TextView) findViewById(R.id.display);
spn_Display = (Spinner)findViewById(R.id.spn_Display);
//Setup the Button's OnClickListener
buttonGetData.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
//Get the data
in = null;
DoPOST mDoPOST = new DoPOST(MainActivity.this, editTextSearchString.getText().toString());
Toast.makeText(getApplicationContext(), editTextSearchString.getText().toString(), 6).show();
mDoPOST.execute("");
buttonGetData.setEnabled(false);
}
});
}
public class DoPOST extends AsyncTask<String, Void, Boolean>
{
Context mContext = null;
String strNameToSearch = "";
//Result data
String strFirstName;
String strLastName;
int intAge;
int intPoints;
Exception exception = null;
DoPOST(Context context, String nameToSearch){
mContext = context;
strNameToSearch = nameToSearch;
}
#Override
protected Boolean doInBackground(String... arg0) {
try{
//Setup the parameters
ArrayList<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>();
nameValuePairs.add(new BasicNameValuePair("Username", "admin"));
nameValuePairs.add(new BasicNameValuePair("Password", "admin123"));
//Create the HTTP request
HttpParams httpParameters = new BasicHttpParams();
//Setup timeouts
HttpConnectionParams.setConnectionTimeout(httpParameters, 15000);
HttpConnectionParams.setSoTimeout(httpParameters, 15000);
HttpClient httpclient = new DefaultHttpClient(httpParameters);
HttpPost httppost = new HttpPost("http://examplesvr4.sample.com:1217/api/subbrands");
HttpGet httpget = new HttpGet("http://examplesvr4.sample.com:1217/api/subbrands");
httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs));
HttpResponse response = httpclient.execute(httpget);
HttpEntity entity = response.getEntity();
result = EntityUtils.toString(entity);
// Create a JSON object from the request response
JSONObject jsonObject = new JSONObject(result);
//Retrieve the data from the JSON object
strFirstName = jsonObject.getString("SubBrandId");
strLastName = jsonObject.getString("SubBrandName");
}catch (Exception e){
Log.e("ClientServerDemo", "Error:", e);
exception = e;
}
return true;
}
#Override
protected void onPostExecute(Boolean valid){
//Update the UI
textViewFirstName.setText("First Name: " + strFirstName);
textViewLastName.setText("Last Name: " + strLastName);
buttonGetData.setEnabled(true);
if(exception != null){
Toast.makeText(mContext, exception.getMessage(), Toast.LENGTH_LONG).show();
}
}
}

Abort image upload on a server

I have an AsyncTask which upload an image to my server. This part works fine, but I can't figure out how to handle an aborting process. I have a ProgressDialog which is cancelable, and a listener on cancel. In this listener I abort the http request and the the AsyncTask... But it seems it is not enough as the image is still uploaded.
Here is how my code looks like :
public class UploadCubeThread extends AsyncTask<Cube, Void, String> {
private static final String url = "http://www.mywebsite.com/upload_cube.php";
private volatile HttpPost httppost = new HttpPost(url);
private ProgressDialog waitSpinner;
private Context context;
private HashMap<String, Integer> feedback;
private boolean success = false;
public UploadCubeThread(Context context) {
this.context = context;
this.feedback = new HashMap<String, Integer>();
waitSpinner = new ProgressDialog(context);
// Cancelable
waitSpinner.setCancelable(true);
waitSpinner.setCanceledOnTouchOutside(false);
waitSpinner.setOnCancelListener(new OnCancelListener() {
public void onCancel(DialogInterface dialog) {
httppost.abort();
UploadCubeThread.this.cancel(true);
}
});
}
#Override
protected void onCancelled() {
super.onCancelled();
success = false;
feedback.put("cancelled", 0);
((UploadListener) context).onUploadComplete(success, feedback);
}
#Override
protected void onPreExecute() {
super.onPreExecute();
waitSpinner.setMessage(context.getString(R.string.uploading));
waitSpinner.show();
}
#Override
protected String doInBackground(Cube... arg0) {
Cube cube = arg0[0];
String result = null;
ByteArrayOutputStream stream = new ByteArrayOutputStream();
// Compression
cube.getImage().compress(Bitmap.CompressFormat.JPEG, 100, stream);
byte[] byte_arr = stream.toByteArray();
String image_str = Base64.encodeBytes(byte_arr);
ArrayList<BasicNameValuePair> nameValuePairs = new ArrayList<BasicNameValuePair>();
// Hash md5 pour l'intégrité
String hash = CubeUploader.encode(image_str);
nameValuePairs.add(new BasicNameValuePair("image", image_str));
nameValuePairs.add(new BasicNameValuePair("id_building", String
.valueOf(cube.getId_building())));
nameValuePairs.add(new BasicNameValuePair("title", cube.getTitle()));
nameValuePairs
.add(new BasicNameValuePair("content", cube.getContent()));
nameValuePairs.add(new BasicNameValuePair("hash", hash));
try {
HttpClient httpclient = new DefaultHttpClient();
httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs,
HTTP.UTF_8));
HttpResponse response = httpclient.execute(httppost);
// Utilisation de la réponse
BufferedReader reader = new BufferedReader(new InputStreamReader(
response.getEntity().getContent(), "UTF-8"));
result = reader.readLine();
} catch (UnknownHostException he) {
Log.e("CubeUpload", "Unknown Host : problem of connectivity ?");
result = "host_pb";
} catch (Exception e) {
Log.e("CubeUpload", "Error during upload: " + e.toString());
}
return result;
}
#Override
protected void onPostExecute(String result) {
super.onPostExecute(result);
//Some process
((UploadListener) context).onUploadComplete(success, feedback);
waitSpinner.dismiss();
}
}
Thank you very much for your help!

I think the point is that httppost.abort();
is not enough and the connection is not completely closed (it's what I want, it'll be handled server side) so I tried to add httpclient.getConnectionManager().shutdown(); after but it's not better, the image is still uploaded ! ... I don't understand

android http post asynctask

Please can anyone tell me how to make an http post to work in the background with AsyncTask and how to pass the parameters to the AsyncTask? All the examples that I found were not clear enough for me and they were about downloading a file.
I'm running this code in my main activity and my problem is when the code sends the info to the server the app slows down as if it is frozen for 2 to 3 sec's then it continues to work fine until the next send. This http post sends four variables to the server (book, libadd, and time) the fourth is fixed (name)
Thanks in advance
public void SticketFunction(double book, double libadd, long time){
Log.v("log_tag", "%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% SticketFunction()");
//HttpClient
HttpClient nnSticket = new DefaultHttpClient();
//Response handler
ResponseHandler<String> res = new BasicResponseHandler();
HttpPost postMethod = new HttpPost("http://www.books-something.com");
try {
List<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>(5);
nameValuePairs.add(new BasicNameValuePair("book", book+""));
nameValuePairs.add(new BasicNameValuePair("libAss", libass+""));
nameValuePairs.add(new BasicNameValuePair("Time", time+""));
nameValuePairs.add(new BasicNameValuePair("name", "jack"));
//Encode and set entity
postMethod.setEntity(new UrlEncodedFormEntity(nameValuePairs, HTTP.UTF_8));
//Execute
//manSticket.execute(postMethod);
String response =Sticket.execute(postMethod, res).replaceAll("<(.|\n)*?>","");
if (response.equals("Done")){
//Log.v("log_tag", "!!!!!!!!!!!!!!!!!! SticketFunction got a DONE!");
}
else Log.v("log_tag", "!!!!!!!?????????? SticketFunction Bad or no response: " + response);
} catch (ClientProtocolException e) {
// TODO Auto-generated catch block
//Log.v("log_tag", "???????????????????? SticketFunction Client Exception");
} catch (IOException e) {
// TODO Auto-generated catch block
//Log.v("log_tag", "???????????????????? IO Exception");
}
}
}

At first,
You put a class like following:
public class AsyncHttpPost extends AsyncTask<String, String, String> {
interface Listener {
void onResult(String result);
}
private Listener mListener;
private HashMap<String, String> mData = null;// post data
/**
* constructor
*/
public AsyncHttpPost(HashMap<String, String> data) {
mData = data;
}
public void setListener(Listener listener) {
mListener = listener;
}
/**
* background
*/
#Override
protected String doInBackground(String... params) {
byte[] result = null;
String str = "";
HttpClient client = new DefaultHttpClient();
HttpPost post = new HttpPost(params[0]);// in this case, params[0] is URL
try {
// set up post data
ArrayList<NameValuePair> nameValuePair = new ArrayList<NameValuePair>();
Iterator<String> it = mData.keySet().iterator();
while (it.hasNext()) {
String key = it.next();
nameValuePair.add(new BasicNameValuePair(key, mData.get(key)));
}
post.setEntity(new UrlEncodedFormEntity(nameValuePair, "UTF-8"));
HttpResponse response = client.execute(post);
StatusLine statusLine = response.getStatusLine();
if(statusLine.getStatusCode() == HttpURLConnection.HTTP_OK){
result = EntityUtils.toByteArray(response.getEntity());
str = new String(result, "UTF-8");
}
}
catch (UnsupportedEncodingException e) {
e.printStackTrace();
}
catch (Exception e) {
}
return str;
}
/**
* on getting result
*/
#Override
protected void onPostExecute(String result) {
// something...
if (mListener != null) {
mListener.onResult(result)
}
}
}
Now.
You just write some lines like following:
HashMap<String, String> data = new HashMap<String, String>();
data.put("key1", "value1");
data.put("key2", "value2");
AsyncHttpPost asyncHttpPost = new AsyncHttpPost(data);
asyncHttpPost.setListener(new AsyncHttpPost.Listener(){
#Override
public void onResult(String result) {
// do something, using return value from network
}
});
asyncHttpPost.execute("http://example.com");

First i would not recommend do a Http request in a AsyncTask, you better try a Service instead. Going back to the issue on how to pass parameter into an AsyncTask when you declared it you can defined each Object class of the AsyncTask like this.
public AsyncTask <Params,Progress,Result> {
}
so in your task you should go like this
public MyTask extends<String,Void,Void>{
public Void doInBackground(String... params){//those Params are String because it's declared like that
}
}
To use it, it's quite simple
new MyTask().execute("param1","param2","param3")