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

User · Answer

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

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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 lt NameValuePair gt  headers ArrayList lt NameValuePair gt  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    gt  1                              combinedParams      amp     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 lt NameValuePair gt  addCommonHeaderField ArrayList lt NameValuePair gt   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

User · Answer

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     lt uses-permission android name  android permission INTERNET  gt   lt  uses-permission gt    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 lt map  void     string    gt        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

User · Answer

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 lt Repo gt  listRepos  Path  user   String user Callback lt List lt User gt  gt  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 lt Repo gt  repos   service listRepos  octocat  new Callback lt List lt User gt  gt            Override     public void failure final RetrofitError error            android util Log i  example    Error  body      error getBody   toString                Override     public void success List lt User gt  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

User · Answer

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

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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

User · Answer

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 amp 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

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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

User · Answer

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  lt --  Object mapping on both sides  Android  Java back-end  you can use GSON

[java] How to call a RESTful web service from Android?

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