Android Kotlin and PHP Retrofit code to log in and Logout

Introduction

Most of the population in the world have smartphones which they mainly use to access social media, follow the news, and as a source of entertainment, As developers, as we develop those applications being used by the growing smartphone population we need to have a look at the most critical aspect which is log in and Logout Functionalities. In the example, we will be implementing login and logout functionality in an Android app using Kotlin and PHP Retrofit.

What is Retrofit?

Retrofit is a type-safe HTTP client for Android and Java. It makes it easy to consume RESTful web services by translating the API into Java or Kotlin interfaces. Retrofit simplifies the process of making network requests by abstracting the details of the HTTP client and providing a clean API for developers to work with.

Implementing Login Functionality

for us To implement login functionality in our Android app, we need to create a login API on the server side. The API will help us to check the user’s credentials (username and password) and return a response indicating if the login was successful or not. example of a PHP implemented login API:

<?php
if ($_SERVER['REQUEST_METHOD'] == 'POST') {
    $username = $_POST['username'];
    $password = $_POST['password'];
    // Check if the username and password are correct
    if ($username == 'admin' && $password == 'password') {
        // Return a success response
        echo json_encode(array('status' => 'success'));
    } else {
        // Return an error response
        echo json_encode(array('status' => 'error', 'message' => 'Invalid username or password'));
    }
}
?>

Once the login API is ready, we can use Retrofit to make a network request to the API from our Android app. Here is an example of how to create a Retrofit client and make a login request:

val retrofit = Retrofit.Builder()
    .baseUrl("http://example.com/")
    .addConverterFactory(GsonConverterFactory.create())
    .build()

val api = retrofit.create(LoginApi::class.java)
val call = api.login("admin", "password")

call.enqueue(object : Callback<LoginResponse> {
    override fun onResponse(call: Call<LoginResponse>, response: Response<LoginResponse>) {
        if (response.isSuccessful) {
            val loginResponse = response.body()
            // Handle success response
        } else {
            // Handle error response
        }
    }

    override fun onFailure(call: Call<LoginResponse>, t: Throwable) {
        // Handle network error
    }
})

In this example, we first create a Retrofit client with the base URL of our server. We also add a Gson converter factory to parse the JSON response from the server. We then create an instance of our login API interface and make a network request using the enqueue method. The PHP onResponse method is called when the server sends a response, and we can handle the success or error response accordingly. The onFailure method is called when there is a network error.

Implementing Logout Functionality

we need to create a logout API on the server side to implement the logout functionality. This API will assist us to invalidate the user’s session and return a response informing us that the logout was successful as well as notify us if not successful. example of a PHP-implemented logout API :

<?php
if ($_SERVER['REQUEST_METHOD'] == 'POST') {
    // Invalidate the user's session
    session_destroy();
    // Return a success response
    echo json_encode(array('status' => 'success'));
}
?>

Once we have the logout API ready, we can use Retrofit to make a network request to the API from our Android app. Here is an example of how to make a logout request:

val retrofit = Retrofit.Builder()
    .baseUrl("http://example.com/")
    .addConverterFactory(GsonConverterFactory.create())
    .build()

val api = retrofit.create(LogoutApi::class.java)
val call = api.logout()

call.enqueue(object : Callback<LogoutResponse> {
    override fun onResponse(call: Call<LogoutResponse>, response: Response<LogoutResponse>) {
        if (response.isSuccessful) {
            val logoutResponse = response.body()
            // Handle success response
        } else {
            // Handle error response
        }
    }

    override fun onFailure(call: Call<LogoutResponse>, t: Throwable) {
        // Handle network error
    }
})

In this example, we create a Retrofit client and an instance of our logout API interface. We then make a network request using the enqueue method. The onResponse method is called when we receive a response from the server, and we can handle the success or error response accordingly. The onFailure method is called when there is a network error.

Conclusion

In our example, we showed how to implement login and logout functionality in an Android app using Kotlin and PHP Retrofit. We saw how to create login and logout APIs on the server side and how to make network requests using Retrofit. By implementing login and logout functionality in your Android app, you can provide your users with a secure and personalized experience.

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