How to call a RESTful web service from Android?

Question

I have written a REST web service in Netbean IDE using Jersey Framework and Java.

For every request the user needs to provide a username and a password, I know that this authentication is not a best practice (using a curl command like: curl -u username:password -X PUT http://localhsot:8080/user).

Now I want to call a REST web service from an Android Class.

How should I do it?

I have an Android Class which uses DefaultHttpClient and CredentialUsernameAndPassword, but when I run it in Eclipse, sometimes I get a runtime exception or SDK exception.

score 19 · Answer 1 · edited Mar 22 '16 at 15:26

This is an sample restclient class

public class RestClient
{
    public enum RequestMethod
    {
        GET,
        POST
    }
    public int responseCode=0;
    public String message;
    public String response;
    public void Execute(RequestMethod method,String url,ArrayList<NameValuePair> headers,ArrayList<NameValuePair> params) throws Exception
    {
        switch (method)
        {
            case GET:
            {
                // add parameters
                String combinedParams = "";
                if (params!=null)
                {
                    combinedParams += "?";
                    for (NameValuePair p : params)
                    {
                        String paramString = p.getName() + "=" + URLEncoder.encode(p.getValue(),"UTF-8");
                        if (combinedParams.length() > 1)
                            combinedParams += "&" + paramString;
                        else
                            combinedParams += paramString;
                    }
                }
                HttpGet request = new HttpGet(url + combinedParams);
                // add headers
                if (headers!=null)
                {
                    headers=addCommonHeaderField(headers);
                    for (NameValuePair h : headers)
                        request.addHeader(h.getName(), h.getValue());
                }
                executeRequest(request, url);
                break;
            }
            case POST:
            {
                HttpPost request = new HttpPost(url);
                // add headers
                if (headers!=null)
                {
                    headers=addCommonHeaderField(headers);
                    for (NameValuePair h : headers)
                        request.addHeader(h.getName(), h.getValue());
                }
                if (params!=null)
                    request.setEntity(new UrlEncodedFormEntity(params, HTTP.UTF_8));
                executeRequest(request, url);
                break;
            }
        }
    }
    private ArrayList<NameValuePair> addCommonHeaderField(ArrayList<NameValuePair> _header)
    {
        _header.add(new BasicNameValuePair("Content-Type","application/x-www-form-urlencoded"));
        return _header;
    }
    private void executeRequest(HttpUriRequest request, String url)
    {
        HttpClient client = new DefaultHttpClient();
        HttpResponse httpResponse;
        try
        {
            httpResponse = client.execute(request);
            responseCode = httpResponse.getStatusLine().getStatusCode();
            message = httpResponse.getStatusLine().getReasonPhrase();
            HttpEntity entity = httpResponse.getEntity();

            if (entity != null)
            {
                InputStream instream = entity.getContent();
                response = convertStreamToString(instream);
                instream.close();
            }
        }
        catch (Exception e)
        { }
    }

    private static String convertStreamToString(InputStream is)
    {
        BufferedReader reader = new BufferedReader(new InputStreamReader(is));
        StringBuilder sb = new StringBuilder();
        String line = null;
        try
        {
            while ((line = reader.readLine()) != null)
            {
                sb.append(line + "\n");
            }
            is.close();
        }
        catch (IOException e)
        { }
        return sb.toString();
    }
}

Adding a class's source code without comments or summarizing what is happening at which point is confusing to someone new to RESTful services such as myself. — J. Schei, Feb 09 '17 at 02:53

score 14 · Answer 2 · answered May 09 '14 at 07:49

Recently discovered that a third party library - Square Retrofit can do the job very well.

Defining REST endpoint

public interface GitHubService {
   @GET("/users/{user}/repos")
   List<Repo> listRepos(@Path("user") String user,Callback<List<User>> cb);
}

Getting the concrete service

RestAdapter restAdapter = new RestAdapter.Builder()
    .setEndpoint("https://api.github.com")
    .build();
GitHubService service = restAdapter.create(GitHubService.class);

Calling the REST endpoint

List<Repo> repos = service.listRepos("octocat",new Callback<List<User>>() { 
    @Override
    public void failure(final RetrofitError error) {
        android.util.Log.i("example", "Error, body: " + error.getBody().toString());
    }
    @Override
    public void success(List<User> users, Response response) {
        // Do something with the List of Users object returned
        // you may populate your adapter here
    }
});

The library handles the json serialization and deserailization for you. You may customize the serialization and deserialization too.

Gson gson = new GsonBuilder()
    .setFieldNamingPolicy(FieldNamingPolicy.LOWER_CASE_WITH_UNDERSCORES)
    .registerTypeAdapter(Date.class, new DateTypeAdapter())
    .create();

RestAdapter restAdapter = new RestAdapter.Builder()
    .setEndpoint("https://api.github.com")
    .setConverter(new GsonConverter(gson))
    .build();

is there any real example about this? i don't quite understand in detail. — Gatunox, Mar 15 '15 at 02:15
Retrofit generates the Restful web services clients for you. You just need to define interfaces with some annotations. For details, see http://square.github.io/retrofit/ — Tianhai, Mar 15 '15 at 09:57
I already look at it. But o still dont get it. Trats why im looking for an real example. No just a few pieces of code — Gatunox, Mar 15 '15 at 13:47
https://github.com/square/retrofit/blob/master/samples/github-client/src/main/java/com/example/retrofit/GitHubClient.java — Tianhai, Mar 15 '15 at 13:52
I have been using Retrofit for a few months and have never had better success with a Java library in my life. I recommend using [Google's Gson library](https://github.com/google/gson) with it, as it makes JSON (de)serialization really really easy. — Chris Cirefice, Aug 04 '15 at 21:24

score 6 · Answer 3 · answered May 31 '13 at 08:01

Stop with whatever you were doing ! :)

Implement the RESTful client as a SERVICE and delegate the intensive network stuff to activity independent component: a SERVICE.

Watch this insightful video http://www.youtube.com/watch?v=xHXn3Kg2IQE where Virgil Dobjanschi is explaining his approach(es) to this challenge...

Igor Vuković · Answer 4 · 2016-08-23T07:36:00.580

2

Using Spring for Android with RestTemplate https://spring.io/guides/gs/consuming-rest-android/

// The connection URL 
String url = "https://ajax.googleapis.com/ajax/" + 
    "services/search/web?v=1.0&q={query}";

// Create a new RestTemplate instance
RestTemplate restTemplate = new RestTemplate();

// Add the String message converter
restTemplate.getMessageConverters().add(new StringHttpMessageConverter());

// Make the HTTP GET request, marshaling the response to a String
String result = restTemplate.getForObject(url, String.class, "Android");

edited Aug 23 '16 at 07:36

answered Aug 22 '16 at 14:53

Igor Vuković

742
12
25

3

Those who down-voted should explain what is wrong with this answer. – jk7 Mar 14 '17 at 16:58

taynguyen · Answer 5 · 2016-11-09T14:15:48.913

1

I used OkHttpClient to call restful web service. It's very simple.

OkHttpClient httpClient = new OkHttpClient();
Request request = new Request.Builder()
                .url(url)
                .build();

Response response = httpClient.newCall(request).execute();
String body = response.body().string()

edited Nov 09 '16 at 14:15

answered Jun 10 '16 at 03:12

taynguyen

2,961
1
26
26

3

That's not a _built-in_ component of Android. – Czechnology Oct 09 '16 at 20:49

score 0 · Answer 6 · answered Jun 21 '14 at 04:57

0

What back-end? If JAVA then you can use REST with Java (JAX-RS) using Jersey.

On the Android side you can use this simple RestClient to work with that REST service.

For JSON <--> Object mapping on both sides (Android, Java back-end) you can use GSON.

answered Jun 21 '14 at 04:57

Komal Nikhare

252
1
4
9

score 0 · Answer 7 · answered Jun 25 '15 at 05:07

Perhaps am late or maybe you've already used it before but there is another one called ksoap and its pretty amazing.. It also includes timeouts and can parse any SOAP based webservice efficiently. I also made a few changes to suit my parsing.. Look it up

score 0 · Answer 8 · answered Apr 12 '16 at 11:37

Follow the below steps to consume RestFul in android.

Step1

Create a android blank project.

Step2

Need internet access permission. write the below code in AndroidManifest.xml file.

 <uses-permission android:name="android.permission.INTERNET">
</uses-permission>

Step3

Need RestFul url which is running in another server or same machine.

Step4

Make a RestFul Client which will extends AsyncTask. See RestFulPost.java.

Step5

Make DTO class for RestFull Request and Response.

RestFulPost.java

package javaant.com.consuming_restful.restclient;
import android.app.ProgressDialog;
import android.content.Context;
import android.os.AsyncTask;
import android.util.Log;
import com.google.gson.Gson;
import org.apache.http.HttpResponse;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.entity.StringEntity;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.util.EntityUtils;
import java.util.Map;
import javaant.com.consuming_restful.util.Util;
/**
 * Created by Nirmal Dhara on 29-10-2015.
 */
public class RestFulPost extends AsyncTask<map, void,="" string=""> {
    RestFulResult restFulResult = null;
    ProgressDialog Asycdialog;
    String msg;
    String task;
    public RestFulPost(RestFulResult restFulResult, Context context, String msg,String task) {
        this.restFulResult = restFulResult;
        this.task=task;
        this.msg = msg;
        Asycdialog = new ProgressDialog(context);
    }
    @Override
    protected String doInBackground(Map... params) {
        String responseStr = null;
        Object dataMap = null;
        HttpPost httpost = new HttpPost(params[0].get("url").toString());

        try {
            dataMap = (Object) params[0].get("data");
            Gson gson = new Gson();
            Log.d("data  map", "data map------" + gson.toJson(dataMap));
            httpost.setEntity(new StringEntity(gson.toJson(dataMap)));
            httpost.setHeader("Accept", "application/json");
            httpost.setHeader("Content-type", "application/json");
            DefaultHttpClient httpclient= Util.getClient();
            HttpResponse response = httpclient.execute(httpost);
            int statusCode = response.getStatusLine().getStatusCode();
            Log.d("resonse code", "----------------" + statusCode);

            if (statusCode == 200)
                responseStr = EntityUtils.toString(response.getEntity());
            if (statusCode == 404) {
                responseStr = "{\n" +
                        "\"status\":\"fail\",\n" +
                        " \"data\":{\n" +
                        "\"ValidUser\":\"Service not available\",\n" +
                        "\"code\":\"404\"\n" +
                        "}\n" +
                        "}";
            }

        } catch (Exception e) {
            e.printStackTrace();
        }
        return responseStr;
    }
    @Override
    protected void onPreExecute() {
        Asycdialog.setMessage(msg);
        //show dialog
        Asycdialog.show();
        super.onPreExecute();
    }
    @Override
    protected void onPostExecute(String s) {
        Asycdialog.dismiss();
        restFulResult.onResfulResponse(s,task);
    }
}

For more details and complete code please visit http://javaant.com/consume-a-restful-webservice-in-android/#.VwzbipN96Hs

score 0 · Answer 9 · answered Feb 22 '17 at 09:53

Here is my Library That I have created for simple Webservice Calling,

You can use this by adding a one line gradle dependency -

compile 'com.scantity.ScHttpLibrary:ScHttpLibrary:1.0.0'

Here is the demonstration of using.

https://github.com/vishalchhodwani1992/httpLibrary

How to call a RESTful web service from Android?

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