How do I send JSon as BODY In a POST request to server from an Android application?

Sending JSON as BODY in a POST Request from Android

This article explains how to send JSON data as the body of a POST request from an Android application to a server.

1. Prepare the JSON Data

1.1 Create a JSON Object

First, you need to create a JSON object containing the data you want to send to the server. You can use libraries like Gson or Jackson to convert Java objects to JSON strings.

import com.google.gson.Gson;
import com.google.gson.JsonObject;

// Create a Java object representing the data
class User {
  String name;
  int age;
  // ... other fields
}

// Create a JSON object from the Java object
User user = new User();
user.name = "John Doe";
user.age = 30;
Gson gson = new Gson();
String jsonString = gson.toJson(user);

// Output: {"name":"John Doe","age":30} 

1.2 Create a JSON String

Alternatively, you can manually create a JSON string using the StringBuilder class.

StringBuilder sb = new StringBuilder();
sb.append("{");
sb.append("\"name\": \"John Doe\",");
sb.append("\"age\": 30");
sb.append("}");
String jsonString = sb.toString();

// Output: {"name":"John Doe","age":30}

2. Send the POST Request

2.1 Using OkHttp

OkHttp is a popular HTTP client library for Android. Here’s how to send a POST request with JSON data using OkHttp:

import okhttp3.MediaType;
import okhttp3.OkHttpClient;
import okhttp3.Request;
import okhttp3.RequestBody;
import okhttp3.Response;

// Create an OkHttp client
OkHttpClient client = new OkHttpClient();

// Set the request body
MediaType JSON = MediaType.parse("application/json; charset=utf-8");
RequestBody body = RequestBody.create(JSON, jsonString);

// Create the POST request
Request request = new Request.Builder()
    .url("https://your-api-endpoint")
    .post(body)
    .build();

// Send the request and handle the response
try {
    Response response = client.newCall(request).execute();
    // Handle the response
} catch (IOException e) {
    // Handle the error
}

2.2 Using Volley

Volley is another widely used library for network communication in Android. Here’s how to send a POST request with JSON data using Volley:

import com.android.volley.Request;
import com.android.volley.RequestQueue;
import com.android.volley.Response;
import com.android.volley.VolleyError;
import com.android.volley.toolbox.JsonObjectRequest;
import com.android.volley.toolbox.Volley;

// Create a Volley request queue
RequestQueue queue = Volley.newRequestQueue(this);

// Create a JsonObjectRequest with the JSON data
JsonObjectRequest jsonObjectRequest = new JsonObjectRequest(
    Request.Method.POST,
    "https://your-api-endpoint",
    new JSONObject(jsonString),
    new Response.Listener() {
        @Override
        public void onResponse(JSONObject response) {
            // Handle the response
        }
    },
    new Response.ErrorListener() {
        @Override
        public void onErrorResponse(VolleyError error) {
            // Handle the error
        }
    }
);

// Add the request to the queue
queue.add(jsonObjectRequest);

3. Server-Side Handling

On the server-side, you need to handle the POST request and parse the incoming JSON data. This involves:

• Receiving the request
• Reading the JSON data from the request body
• Processing the data and responding to the client

The specific implementation will vary depending on the server-side technology you’re using (e.g., Node.js, Java, Python).

4. Example: Sending User Data

Here’s a complete example of sending user data as a JSON object in a POST request using OkHttp:

// Android application code
import android.os.AsyncTask;
import okhttp3.*;

public class SendUserData extends AsyncTask {

    @Override
    protected String doInBackground(Void... voids) {
        try {
            // Create the JSON data
            User user = new User();
            user.name = "John Doe";
            user.age = 30;
            Gson gson = new Gson();
            String jsonString = gson.toJson(user);

            // Create an OkHttp client
            OkHttpClient client = new OkHttpClient();

            // Set the request body
            MediaType JSON = MediaType.parse("application/json; charset=utf-8");
            RequestBody body = RequestBody.create(JSON, jsonString);

            // Create the POST request
            Request request = new Request.Builder()
                    .url("https://your-api-endpoint")
                    .post(body)
                    .build();

            // Send the request and get the response
            Response response = client.newCall(request).execute();
            return response.body().string();
        } catch (Exception e) {
            return e.getMessage();
        }
    }

    @Override
    protected void onPostExecute(String result) {
        // Handle the response from the server
        // ...
    }
}

You’ll need to replace “https://your-api-endpoint” with the actual URL of your server endpoint.

Comparison: OkHttp vs Volley

Conclusion

This article covered how to send JSON data as the body of a POST request from an Android application using OkHttp and Volley. Remember to choose the library that best suits your needs and follow the server-side instructions for processing the data.