¿Cómo publicar datos en la API usando Retrofit en Android?

Hemos visto leer datos de API en nuestra aplicación de Android en Android Studio. Para leer datos de la API, usamos la solicitud GET para leer nuestros datos que están en formato JSON . En este artículo, veremos cómo agregar datos a la API REST en nuestra aplicación de Android en Android Studio. 

¿Qué vamos a construir en este artículo? 

Construiremos una aplicación simple en la que agregaremos datos a nuestra API REST utilizando la biblioteca Retrofit con POST Request. Agregaremos los datos a través de campos de texto de edición y verificaremos a través del código de respuesta si nuestros datos se agregaron a la API o no. Cuando agreguemos datos a nuestra API, veremos 201 como un código de respuesta. El código de respuesta 201 significa que se han agregado datos a nuestra API. A continuación se muestra un video de muestra para tener una idea de lo que vamos a hacer en este artículo. Tenga en cuenta que vamos a implementar este proyecto utilizando el  lenguaje Java  . 

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

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context=".MainActivity">
  
    <!--edit text field for adding name-->
    <EditText
        android:id="@+id/idEdtName"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_margin="10dp"
        android:layout_marginTop="40dp"
        android:hint="Enter your name" />
  
    <!--edit text for adding job-->
    <EditText
        android:id="@+id/idEdtJob"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_margin="10dp"
        android:hint="Enter your job" />
  
    <!--button for adding data-->
    <Button
        android:id="@+id/idBtnPost"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_margin="20dp"
        android:text="Send Data to API"
        android:textAllCaps="false" />
  
    <!--text view for displaying our API response-->
    <TextView
        android:id="@+id/idTVResponse"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_margin="10dp"
        android:gravity="center_horizontal"
        android:text="Response"
        android:textAlignment="center"
        android:textSize="15sp" />
  
    <!--progress bar for loading -->
    <ProgressBar
        android:id="@+id/idLoadingPB"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center"
        android:visibility="gone" />
  
</LinearLayout>

public class DataModal {
      
    // string variables for our name and job
    private String name;
    private String job;
  
    public DataModal(String name, String job) {
        this.name = name;
        this.job = job;
    }
  
    public String getName() {
        return name;
    }
  
    public void setName(String name) {
        this.name = name;
    }
  
    public String getJob() {
        return job;
    }
  
    public void setJob(String job) {
        this.job = job;
    }
      
}

import retrofit2.Call;
import retrofit2.http.Body;
import retrofit2.http.POST;
  
public interface RetrofitAPI {
      
    // as we are making a post request to post a data
    // so we are annotating it with post
    // and along with that we are passing a parameter as users
    @POST("users")
      
    //on below line we are creating a method to post our data.
    Call<DataModal> createPost(@Body DataModal dataModal);
}

import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ProgressBar;
import android.widget.TextView;
import android.widget.Toast;
  
import androidx.appcompat.app.AppCompatActivity;
  
import retrofit2.Call;
import retrofit2.Callback;
import retrofit2.Response;
import retrofit2.Retrofit;
import retrofit2.converter.gson.GsonConverterFactory;
  
public class MainActivity extends AppCompatActivity {
  
    // creating variables for our edittext, 
    // button, textview and progressbar.
    private EditText nameEdt, jobEdt;
    private Button postDataBtn;
    private TextView responseTV;
    private ProgressBar loadingPB;
  
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
          
        // initializing our views
        nameEdt = findViewById(R.id.idEdtName);
        jobEdt = findViewById(R.id.idEdtJob);
        postDataBtn = findViewById(R.id.idBtnPost);
        responseTV = findViewById(R.id.idTVResponse);
        loadingPB = findViewById(R.id.idLoadingPB);
          
        // adding on click listener to our button.
        postDataBtn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                // validating if the text field is empty or not.
                if (nameEdt.getText().toString().isEmpty() && jobEdt.getText().toString().isEmpty()) {
                    Toast.makeText(MainActivity.this, "Please enter both the values", Toast.LENGTH_SHORT).show();
                    return;
                }
                // calling a method to post the data and passing our name and job.
                postData(nameEdt.getText().toString(), jobEdt.getText().toString());
            }
        });
    }
  
    private void postData(String name, String job) {
          
        // below line is for displaying our progress bar.
        loadingPB.setVisibility(View.VISIBLE);
          
        // on below line we are creating a retrofit 
        // builder and passing our base url
        Retrofit retrofit = new Retrofit.Builder()
                .baseUrl("https://reqres.in/api/")
                // as we are sending data in json format so 
                // we have to add Gson converter factory
                .addConverterFactory(GsonConverterFactory.create())
                // at last we are building our retrofit builder.
                .build();
        // below line is to create an instance for our retrofit api class.
        RetrofitAPI retrofitAPI = retrofit.create(RetrofitAPI.class);
          
        // passing data from our text fields to our modal class.
        DataModal modal = new DataModal(name, job);
          
        // calling a method to create a post and passing our modal class.
        Call<DataModal> call = retrofitAPI.createPost(modal);
          
        // on below line we are executing our method.
        call.enqueue(new Callback<DataModal>() {
            @Override
            public void onResponse(Call<DataModal> call, Response<DataModal> response) {
                // this method is called when we get response from our api.
                Toast.makeText(MainActivity.this, "Data added to API", Toast.LENGTH_SHORT).show();
                  
                // below line is for hiding our progress bar.
                loadingPB.setVisibility(View.GONE);
                  
                // on below line we are setting empty text
                // to our both edit text.
                jobEdt.setText("");
                nameEdt.setText("");
                  
                // we are getting response from our body 
                // and passing it to our modal class.
                DataModal responseFromAPI = response.body();
                  
                // on below line we are getting our data from modal class and adding it to our string.
                String responseString = "Response Code : " + response.code() + "\nName : " + responseFromAPI.getName() + "\n" + "Job : " + responseFromAPI.getJob();
                 
                // below line we are setting our 
                // string to our text view.
                responseTV.setText(responseString);
            }
  
            @Override
            public void onFailure(Call<DataModal> call, Throwable t) {
                // setting text to our text view when 
                // we get error response from API.
                responseTV.setText("Error found is : " + t.getMessage());
            }
        });
    }
}