Develop Reference

Http get pass parameters

Im new to Android development but Im trying to do an application for Opencart to allow users to enter in their own store to administrate it.
Lets go to the point. In order to get the information from the store i created a page where all the information is presented in XML, so the idea is that the user login, and then redirects to this page and with the http response, parse the xml and voilá!.
I have already the xml parser, but Im having some difficulties with the http connection. Let me explain a little bit more:
Basically, to log into any store, you need to go to www.example.com/admin (I will be using my testing online address to see if someone is able to help me), in this case http://www.onlineshop.davisanchezplaza.com/admin . Once we arrive to the page we arrive to the login system. The login system uses post to send the username: admin and password:admin and redirects to http://onlineshop.davidsanchezplaza.com/admin/index.php?route=common/login and once it verify your identity, it gives you a Token (here I start having some problems). http://onlineshop.davidsanchezplaza.com/admin/index.php?route=common/home&token=8e64583e003a4eedf54aa07cb3e48150 . Well, till here, im very okay, and actually developed an app that can do till here, actually i can "hardcode" read the token from the http response it sends me (what is actually not very good).
Here comes my first question: HOW TO GET FROM THE HTTPresponse the token value? (by now, as I said, I can only get the token by reading all the response, and if we find the string token=, take what comes next ... not good).
HttpClient httpClient = new DefaultHttpClient();
HttpConnectionParams.setConnectionTimeout(httpClient.getParams(), TIMEOUT_MS);
HttpConnectionParams.setSoTimeout(httpClient.getParams(), TIMEOUT_MS);
HttpPost httpPost = new HttpPost("http://onlineshop.davidsanchezplaza.com/admin/index.php?route=common/login");
List<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>();
nameValuePairs.add(new BasicNameValuePair("username", "admin"));
nameValuePairs.add(new BasicNameValuePair("password", "admin"));
try{
Log.d(DEBUG_TAG, "Try ");
httpPost.setEntity(new UrlEncodedFormEntity(nameValuePairs));
HttpResponse response = httpClient.execute(httpPost);
BufferedReader br = new BufferedReader(new InputStreamReader(response.getEntity().getContent()), 8096);
Log.d(DEBUG_TAG, "br :" + br);
String line;
while ((line = br.readLine()) != null) {
Log.d(DEBUG_TAG, "br :" + line);
if(line.contains("token=")){
int index = line.indexOf("token=");
String aux = line.substring(index + "token=".length(), index + 32 + "token=".length());
token = aux; //Yes, I know, its not the best way.
break;
}
}
} catch (IOException e) {
Log.d(DEBUG_TAG, "Finally");
}
Second question, (and more important), now having the token (in the example 8e64583e003a4eedf54aa07cb3e48150), I need to go to the route android/home where is the xml information generated. (http://onlineshop.davidsanchezplaza.com/admin/index.php?route=android/home2&token=8e64583e003a4eedf54aa07cb3e48150). As I was reading, in httpget, we can either set the parameters, or directly send the url with the parameters already inside the url. Is in this step where it stops. Maybe is the internet connexion in China, maybe (most sure) im doing something wrong. Sometimes it just come the timeout connexion, others it just send me back to the login page.
Here is the code how i do (edit: I was a noob, and didnt create the httpclient to receive the answer, sorry!):
String s = "http://onlineshop.davidsanchezplaza.com/admin/index.php?route=common/home&token=";
String tot = s.concat(token);
HttpClient httpClient = new DefaultHttpClient();
HttpConnectionParams.setConnectionTimeout(httpClient.getParams(), TIMEOUT_MS);
HttpConnectionParams.setSoTimeout(httpClient.getParams(), TIMEOUT_MS);
HttpGet httpget = new HttpGet(tot);
try{
Log.d(DEBUG_TAG, "Try ");
HttpResponse response = httpClient.execute(httpget);
BufferedReader br = new BufferedReader(new InputStreamReader(response.getEntity().getContent()), 8096);
Log.d(DEBUG_TAG, "br :" + br);
} catch (IOException e) {
Log.d(DEBUG_TAG, "Finally");
}
I dont need someone to tell me how to do it, just need a little guidance to solve the issue, I really appreciate any comment or help you can offer, or extra documentation :).
As a bonus, if someone can give me further details about how can I test the http get, I will appreciate, I only know how to write it in the web browser, and works fine.

It's a while since I last did something for Android, but here is my advice:
for the login purpose from Android application into the OpenCart administration I recommend creating a new mobile login page, e.g. instead of accessing http://yourstore.com/admin/ which redirects You to http://.../admin/index.php?route=common/login create Your own action e.g. androidLogin() within this controller (admin/controller/common/login.php and You will access it directly via http://yourstore.com/admin/index.php?route=common/login/androidLogin. Why special action? Because the default login action redirects the user (using normal browser) to the home while setting the security token into the URL within the query string part. In Your own action You won't redirect but respond with XML containing this security token so that You can easily extract that token using Your XML parser.
I cannot address second problem exactly but from what I remember I was passing a query string in different way (now I cannot find any similar solution on the internet).

Here is my 5 cents for the second question :
After playing a bit with the browser I realized :
Set Cookies
Your request to ...?route=android/home2&token= seems to be rejected if you are missing cookies. That is, you probably need to extract cookies from first server response and set them for further requests either manually (via conn.setRequestProperty("Cookie", cookie); or using Android CookieManager
User agent
Some server may reject your request just because you are missing "User-Agent" property in request header. To be safe, you could set it to something like conn.setRequestProperty("User-Agent", "Mozilla/5.0");
Extra note - I suggest that you also handle redirects correctly, as for example when you POST your admin/admin credentials you get 302 response and redirected to ...?route=common/home page
Also, you don't need to set conn.setDoInput(true) for UrlConnection while doing GET request.
Hope that helps.

I don't see any catch statement for the try in the second question, this catch may have the info you need to know what's going on.
For the first question try to convert InputStreamReader to a String, and use the String for a
url constructor, with the url (or uri i'm not sure right now, and can't test it) object try .getQueryParameter("parameter").

For your second question when i tried to login using the token that you have provided, the web page replied with invalid token. Can you login with the token that you have provided? If not, try to get a new token. Maybe the token have expired.

Consuming Web service from Android Application

I am a beginner on Android app development. I want to confirm if my approach is correct and as per best practices in Android world.
I have an android application that needs textual data (no graphic, video). The data comes from REST based web service as JSON string. I consume this web service using HttpGet object, parse json string using JSONArray and display data.
All this happens in a button click.
My questions are:
Is there a better (or android-style) approach to do the same?
What is the preferred approach to retrieve and post graphic contents to REST based web service?
Any help is most appreciated.
Thanks

Please find my inline commnets,
All this happens in a button click.
My questions are:
Is there a better (or android-style) approach to do the same?
Ideal approach to trigger the Webservice calls in Async task or in a service, so your UI thread will not be blocked till HTTP fires and get the response.
What is the preferred approach to retrieve and post graphic contents to REST based web service?
The graphics content will be usually base64 when you try to retrieve it from the backend.
Refer this example : http://androidtrainningcenter.blogspot.in/2012/03/how-to-convert-string-to-bitmap-and.html
for the posting the graphics to the server
I'm going to assume that you know the path and filename of the image that you want to upload. Add this string to your NameValuePair using image as the key-name.
Sending images can be done using the HttpComponents libraries. Download the latest HttpClient (currently 4.0.1) binary with dependencies package and copy apache-mime4j-0.6.jar and httpmime-4.0.1.jar to your project and add them to your Java build path.
You will need to add the following imports to your class.
import org.apache.http.entity.mime.HttpMultipartMode;
import org.apache.http.entity.mime.MultipartEntity;
import org.apache.http.entity.mime.content.FileBody;
import org.apache.http.entity.mime.content.StringBody;
Now you can create a MultipartEntity to attach an image to your POST request. The following code shows an example of how to do this:
public void post(String url, List nameValuePairs) {
HttpClient httpClient = new DefaultHttpClient();
HttpContext localContext = new BasicHttpContext();
HttpPost httpPost = new HttpPost(url);
try {
MultipartEntity entity = new MultipartEntity(HttpMultipartMode.BROWSER_COMPATIBLE);
for(int index=0; index < nameValuePairs.size(); index++) {
if(nameValuePairs.get(index).getName().equalsIgnoreCase("image")) {
// If the key equals to "image", we use FileBody to transfer the data
entity.addPart(nameValuePairs.get(index).getName(), new FileBody(new File (nameValuePairs.get(index).getValue())));
} else {
// Normal string data
entity.addPart(nameValuePairs.get(index).getName(), new StringBody(nameValuePairs.get(index).getValue()));
}
}
httpPost.setEntity(entity);
HttpResponse response = httpClient.execute(httpPost, localContext);
} catch (IOException e) {
e.printStackTrace();
}
}
Hope this helps!

Hey refer this link which will train you better in parsing json data as you required in Android App. Loading the graphic required some lazy loading mechanism which you can refer it from here.

Can I send a Android HttpGet (not HttpPost) with 1 string param?

Im coding a RESTful API & Android client at the same time as I go and im currently working on pulling the users profile from the server. I feel like this should definitely be a get request being that im only pulling existing data and im not adding/editing anything to my database, but I do need a user_id param to be able to query for the appropriate profile. Can I send just one tiny little variable along with my HttpGet some how or am i supposed to use a HttpPost in this situation regardless?

Android uses Apache's HTTPClient. So, copying their tutorial code:
public void sendStringTo(String remoteUrl, String myString) {
DefaultHttpClient httpclient = new DefaultHttpClient();
HttpGet httpGet = new HttpGet(remoteUrl+"?string1="+myString);
HttpResponse response1 = httpclient.execute(httpGet);
// The underlying HTTP connection is still held by the response object
// to allow the response content to be streamed directly from the network socket.
// In order to ensure correct deallocation of system resources
// the user MUST either fully consume the response content or abort request
// execution by calling HttpGet#releaseConnection().
try {
System.out.println(response1.getStatusLine());
HttpEntity entity1 = response1.getEntity();
// do something useful with the response body
// and ensure it is fully consumed
EntityUtils.consume(entity1);
} finally {
httpGet.releaseConnection();
}
return;
}

GET can support adding variables/parameters. For example you could make a Url that looks like this:
http://yourwebsite.com/script.php?user_id=19898424

Download Data from Server in android 2.1

I want to download some contacts saved on my online server and then display them in my activity. I have written a service and I am giving the code snippet from onStartCommand function, where this downloading is being done.
public int onStartCommand(Intent intent, int flags, int startId)
{
String responseStr = "";
try
{
DefaultHttpClient httpClient = new DefaultHttpClient();
HttpPost httpPost = new HttpPost(URL);
List<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>(2);
nameValuePairs.add(new BasicNameValuePair("action", "get_contact"));
nameValuePairs.add(new BasicNameValuePair("uId", uId + ""));
httpPost.setEntity(new UrlEncodedFormEntity(nameValuePairs));
HttpResponse httpResponse = httpClient.execute(httpPost);
BufferedReader in = new BufferedReader (new InputStreamReader(httpResponse.getEntity().getContent()));
responseStr = in.readLine();
in.close();
}
catch (ClientProtocolException e)
{
Log.e("EXCEPTION", "ClientProtocolException");
}
catch (IOException e)
{
Log.e("EXCEPTION", "IOException");
}
this.stopSelf();
return Service.START_STICKY;
}
But the problem with this code is that it takes too much time to download the data. Kindly suggest me any way to download and display this data in my activity quickly.
Thanks in advance for your help.

Well, if your server or connection is slow, there is not much you can do with your client code.
But, you should definitely consider compressing the responses from your web server and on the client code, add the header:
Accept-Encoding: gzip

There is no guarantee that you will not experience slow download or timeouts even after you enable compression at the HTTP level. At the end of the day you are dealing with unbounded data set and what works in your development environment may not work in the field with a very slow connection where a user may have 25000 contacts all with very long name.
It might be worth looking at the problem in general, considering whether you really need to load all the data right away. You may want to use some sort of pagination (see this question for example and/or use EndlessAdapter).

Try using a socket connection instead.

The thing I notice is you are not doing the download as a background task. Unless your service is running as a separate process from your main activity then this code will execute in the main application (UI) thread of the application and will negatively affect your users. I would recommend you move the code to a AsyncTask or thread launched from onStartCommand. I would then utilize a callback from the service to notify the activity that data is available to display. Also as Dmitry recommends, pagination could help you out as well for the actual download duration.

Uploading images to a PHP server from Android

I need to upload an image to a remote PHP server which expects the following parameters in HTTPPOST:
*$_POST['title']*
*$_POST['caption']*
*$_FILES['fileatt']*
Most of the internet searches suggested either :
Download the following classes and trying MultiPartEntity to send the request:
apache-mime4j-0.5.jar
httpclient-4.0-beta2.jar
httpcore-4.0-beta3.jar
httpmime-4.0-beta2.jar
OR
Use URLconnection and handle multipart data myself.
Btw, I am keen on using HttpClient class rather than java.net(or is it android.net) classes. Eventually, I downloaded the Multipart classes from the Android source code and used them in my project instead.
Though this can be done by any of the above mentioned methods, I'd like to make sure if these are the only ways to achieve the said objective. I skimmed through the documentation and found a FileEntity class but I could not get it to work.
What is the correct way to get this done in an Android application?
Thanks.

The Android source seems to come with an internal multipart helper library. See this post. At a quick glance, it's better documented than plenty of public APIs (cough cough, SoundPool, cough cough), so it should be a pretty good place to start, or possibly fine to just use a drop-in solution.

Maybe this post on the official Android group helps. The guy is using mime4j.
Another helpful resource could be this example in the Pro Android book.

I do exactly that to interact with an image hosting server (implemented also in php) that expects parameters as if they were posted from an html page.
I build a List<NameValuePair> of my keys and values something like this:
List<NameValuePair> params = new ArrayList<NameValuePair>(2);
params.add(new BasicNameValuePair(key1, value1));
params.add(new BasicNameValuePair(key2, value2));
and then I pass it to my http helper class that sets the HttpEntity property of my HttpPost request. Here's the method straight out of my helper class:
public static HttpResponse Post(String url, List<NameValuePair> params, Context context)
{
HttpResponse response = null;
try
{
HttpPost request = new HttpPost();
request.setURI(new URI(url));
if(params != null)
request.setEntity(new UrlEncodedFormEntity(params));
HttpClient client = ((ApplicationEx)context.getApplicationContext()).getHttpClient();
response = client.execute(request);
}
catch(Exception ex)
{
// log, etc
}
return response;
}