Retrofit 2.0 Android | Web service using Retrofit.

Retrofit is developed by Square, Inc. It is one of the most popular HTTP Client Library for Android as a result of its simplicity and its great performance compare to the others.

A part from development,Old method to using web service which is quite lengthy and time consuming.

Here retrofit set everything for you automatically. Now Lets implement Retrofit in our code.

Step 1 : Create studio project.

Now we will Add Retrofit library to our project : Visit Retrofit Official Site
For Android Studio you just need to paste below line of code under dependency of  build.gradle file.

compile 'com.squareup.retrofit2:retrofit:2.0.1'

Now, Add Another library called Okhttp to our project

compile 'com.squareup.okhttp:okhttp:2.4.0' 

Now, Add two more Library Gson and GsonConverter to build.gradle

compile 'com.google.code.gson:gson:1.7.2' 

compile 'com.squareup.retrofit:converter-gson:2.0.0-beta2'

Now, Add one more lib to display log of request and response from retrofit.

compile 'com.squareup.okhttp:logging-interceptor:2.6.0'

SERVICE : 

Let's take Login service to implement using retrofit. below is the service for user login which have two parameter Username and password.

http://xyz/service/userlogin?Username=xyz&password=abc

Step 2: Create POJO/Class

Now we will make all POJO of JSON data coming from server. in my case here is the JSON response of the server.

{"status":"true","message":"Login successfully","data":{"id":1,"first_name":"Hasmukh","last_name":"Bhadani"}}

POJO class in Retrofit by Most Easiest Way :

• Visit pojo.sodhanalibrary - This is Official website to Convert JSON Data into POJO class. Just You have to Copy Paste all the Codes. Rename pojo as per your requirement.

Here I am creating Three POJO : (1)BaseResponse (2)LoginResponse. (3)UserInfo

BaseResponse :

It contain common filed which is used for whole server in the project.

  public class BaseResponse {

    private String message;

    private String status;

    public String getMessage ()
    {
        return message;
    }

    public void setMessage (String message)
    {
        this.message = message;
    }

    public boolean getStatus ()
    {
        return status.equalsIgnoreCase("true");
    }

    public void setStatus (boolean status)
    {
        this.status = String.valueOf(status);
    }
}

LoginResponse :

   public class LoginResponse extends BaseResponse
{
    private Data data;
    public Data getData ()
    {
        return data;
    }
    public void setData (Data data)
    {
        this.data = data;
    }
   
}

UserInfo: 

   public class UserInfo
{
     private String id;

    private String first_name;

    private String last_name;

    public String getId ()
    {
        return id;
    }

    public void setId (String id)
    {
        this.id = id;
    }

    public String getFirst_name ()
    {
        return first_name;
    }

    public void setFirst_name (String first_name)
    {
        this.first_name = first_name;
    }

    public String getLast_name ()
    {
        return last_name;
    }

    public void setLast_name (String last_name)
    {
        this.last_name = last_name;
    }
   
}

Step 3: Create RestClient.java

import com.squareup.okhttp.OkHttpClient;
import com.squareup.okhttp.logging.HttpLoggingInterceptor;
import com.truckforload.app.AppUrls;
import java.util.concurrent.TimeUnit;
import retrofit.GsonConverterFactory;
import retrofit.Retrofit;

public class RestClient
{
    private static ApiInterface restClient;
    static
    {
        setupRestClient();
    }
    private RestClient() {}

    public static ApiInterface get()
    {
        return restClient;
    }
    private static void setupRestClient()
    {
        OkHttpClient client = new OkHttpClient();
        client.setConnectTimeout(10, TimeUnit.SECONDS);

        HttpLoggingInterceptor interceptor = new HttpLoggingInterceptor();
        interceptor.setLevel(HttpLoggingInterceptor.Level.BASIC);

        HttpLoggingInterceptor interceptorBody = new HttpLoggingInterceptor();
        interceptor.setLevel(HttpLoggingInterceptor.Level.BODY);

        client.interceptors().add(interceptor);
        client.interceptors().add(interceptorBody);

        Retrofit retrofit = new Retrofit.Builder()
                .baseUrl(AppUrls.BASE_URL)
                .client(client)
                .addConverterFactory(GsonConverterFactory.create())
                .build();

        restClient = retrofit.create(ApiInterface.class);
    }
}

Step 4: Create ApiInterface.java

Now create an Interface for all http methods and parameter.

import retrofit.Call;
import retrofit.http.Body;
import retrofit.http.GET;
import retrofit.http.POST;
import retrofit.http.Query;

public interface ApiInterface
{
    // Login
    @GET("service/userlogin")
    Call<LoginResponse> login( @Query("Username") String strUsername, @Query("password") String strpassword);

}

Step 5: Create AppWs.java

It contain all method of project which are used for service.And it will provide response using call back listener.

import retrofit.Call;
import retrofit.Callback;
import retrofit.Response;
import retrofit.Retrofit;

public class AppWs
{
    private static final String TAG = "AppWs";

    public static String login( final LoginRequest request, final Context context, final WsListener listener )
    {
        String unm= request.getUsername();
        String password = request.getPassword();

        Call<LoginResponse> call = RestClient.get().login(unm, password);
        try
        {
            call.enqueue(new Callback<LoginResponse>()
            {
                @Override
                public void onResponse( Response<LoginResponse> response, Retrofit retrofit )
                {
                    LoginResponse baseResponse = response.body();
                    if ( baseResponse != null && response.isSuccess() )
                    {
                        if ( listener != null )
                        {
                            listener.onResponseSuccess(baseResponse);
                        }
                    }
                    else
                    {
                        if ( listener != null )
                        {
                            ResponseBody errorBody = response.errorBody();

                            if ( errorBody != null )
                            {
                                listener.notifyResponseFailed(errorBody.toString(), null);
                            }
                        }

                    }
                }

                @Override
                public void onFailure( Throwable t )
                {
                    retrofitError(t, listener, context);
                }

            });

        }
        catch ( Exception e )
        {
            e.printStackTrace();
        }
        return "";
    }


    public static void retrofitError( Throwable t, WsListener listener, Context context )
    {
        if ( listener != null )
        {
            t.printStackTrace();
            listener.notifyResponseFailed(null, null);
        }
    }

    public interface WsListener
    {
        void onResponseSuccess( BaseResponse baseResponse );

        void notifyResponseFailed( String message, BaseRequest request );
    }
}

Step 6: Create MainActivity.java

Below is the Method which is call on SignIn Button in the activity

private void callServiceLogin()
    {
  ProgressDialog progressDialog = new ProgressDialog(this);
  progressDialog.setMessage("Loading...");
  progressDialog.setCancelable(false);

        LoginRequest loginRequest = new LoginRequest();

        String phone = etUserName.getText().toString();
        loginRequest.setUsername(phone);

        String password = etPassword.getText().toString();
        loginRequest.setPassword(password);

        AppWs.login(loginRequest, this, new AppWs.WsListener()
        {
            @Override
            public void onResponseSuccess( BaseResponse baseResponse )
            {
  if (progressDialog != null && progressDialog.isShowing())
             {
                 progressDialog.dismiss();
             }

                if ( baseResponse instanceof LoginResponse )
                {
                    LoginResponse loginResponse = (LoginResponse) baseResponse;

                    boolean status = loginResponse.getStatus();
                    UserInfo userInfo = loginResponse.getData();
                }
            }

            @Override
            public void notifyResponseFailed( String message, BaseRequest request )
            {
                dismissProgressDialog();                
            }
        });

    }

Here is the official site to get more API interface declaration for service. Visit here.

Find following are the reference links to go in deep for retrofi 2.0 :
https://guides.codepath.com/android/Consuming-APIs-with-Retrofit
http://www.iayon.com/consuming-rest-api-with-retrofit-2-0-in-android/

I will be happy if you will provide your feedback or follow this blog. Any suggestion and help will be appreciated.

Thank you :)