Introduction to Kotlin HTTP Client

Kotlin Http client is used in getting and post requests; this is used how we can send the get and post request in kotlin. Http is a hypertext transfer protocol that was used in collaborative and distributed information systems. Http is the data communication found in the whole world. We are using the ktor framework to make an http client request in kotlin, which helps to build the application.

Key Takeaways

• In Kotlin, we are sending the post request by using URLConnection.setDoOutput function by setting it true also, we are writing the post parameters to the connection of the output stream.
• The http url connection class is a subclass for the URL connection, which offers several features of http.

What is Kotlin HTTP Client?

We can use the ktor framework or any other framework to make an http client request to an API to get the response back from the application. Adding the network capabilities for an application that was developed for the toolkit of traditional UI is very straightforward in the kotlin framework. By using the ktor framework in kotlin we can post http client requests, which were asynchronous that were running on multiple platforms like android, JavaScript, IOS, and other platforms. We can send an http request in kotlin by using the java.net URL connection class. It is very useful and important to send the request.

Kotlin HTTP Client Requests

For sending the client request by using http client in kotlin, if suppose we are using the latest version of JDK, then we can make use of the new API of http client, which is fully compatible. It will support the version of http 2.0 also it will support the web sockets, and also it was fully synchronous, which was integrating the Coroutines.

Below we are creating the new request of the http client and passing the object of the http request as follows.

Code:

  fun main () {
  val kotlin_client = HttpClient.newBuilder().build();
  val client_request = HttpRequest.newBuilder()
  .uri (URI.create("https://test.com"))
  .build();
val client_response = kotlin_client.send(client_request, BodyHandlers.ofString());
  println(client_response.body())
  }

Output:

The API is also supporting to perform the request, which was asynchronous. If suppose we are using then we can use completion stage wait as follows.

Code:

fun main() {
suspend fun getData (): String {
val client_res = client.sendAsync (request, BodyHandlers.ofString ());
return client_res.await ().body()
}
val data = getData ()
process (data)
}

Output:

The most commonly used library in http client requests is fuel. This library is fully featured; we can also use the default settings of configuration to get it up and running. Fuel also makes the library result, which was returned from the same creator for bundling up the response and error conditions. The below example shows how fuel is working into the request.

Code:

when (res) {
is Res.Failure -> {
val exp = res.getException()
}
is Res.Success -> {
val data = res.get()
   } }
}

Output:

We can also use the ktor client to make the request of the http client. The below example shows how a ktor client will make requests in kotlin.

Code:

val kotlin_client = HttpClient (Apache) {
install (JsonFeature) {
serializer = GsonSerializer()
   }
}
val htmlContent = kotlin_client.get ("https://test.org/")

Output:

Suppose we are using the dedicated library, then we do not need to do any custom configuration as follows.

Code:

val response = try {
URL ("http://tes.com")
.openStream()
.bufferedReader()
.use { it.readText() }

Output:

Configuration

To use the http client in kotlin, we need to add an http dependency.

The below steps shows the configuration of the http client as follows.:

1. For using the library in our project, we need to add the below dependency as follows.

Code:

 khttp 
 khttp 
 0.1.0 

Output:

2. After adding the dependency, we are adding the repository directive as follows.

Code:

 kotlin  http://test.com 

Output:

3. After adding the repository directive now in the below example, we are configuring the http client request as follows.

Code:

fun main() {
val kot_client = HttpClient.newBuilder().build();
val req = HttpRequest.newBuilder()
.uri(URI.create("http://test.me"))
.build();
val res = kot_client.send(req, HttpResponse.BodyHandlers.ofString ());
println(res.body ())
}

Output:

Kotlin HTTP Client Methods

Basically, there are two types of methods available for http client i.e. http get and http post. Below is the example of those methods as follows:

1. HTTP GET

The http get method requests the specified resource representation. Request by using get it will only retrieve the data.

The below example shows get request with http client as follows:

Code:

fun main() {
val http_client = HttpClient.newBuilder().build ();
val request = HttpRequest.newBuilder()
.uri (URI.create ("http://example.me"))
.build ();
val res = http_client.send(request, HttpResponse.BodyHandlers.ofString ());
println (res.body())
}

Output:

2. HTTP POST

The http post method will send data to the server. This method is used at the time of uploading the file or submitting any web form. The below example shows the http post request method as follows.

Code:

fun main() {
val stud = mapOf("stud_name" to "ABC")
val map = ObjectMapper()
val req: String = map
.writeValueAsString (stud)
val http_client = HttpClient.newBuilder().build();
val req = HttpRequest.newBuilder()
.uri(URI.create("https://post.org"))
.POST(HttpRequest.BodyPublishers.ofString(req))
.build()
val res = http_client.send(req, HttpResponse.BodyHandlers.ofString());
println(res.body())
}

Output:

FAQ

Given below is the FAQ mentioned:

Q1. What is the type of http client request method available in kotlin?

Answer:

Basically, there are two types of http client request methods available in kotlin i.e. HTTP GET and HTTP POST.

Q2. What is HttpUrlConnection?

Answer:

The http url connection is the subclass of a URL connection which was offering several features of the http. For getting the http url connection, we can cast the instance of URL connection.

Q3. What is kotlin http client API?

Answer:

The http client API is used to perform the asynchronous requests. Using the http client API, we create a new http client and pass the object of the http request.

Conclusion

Using the ktor framework, we can post the http client request, which was asynchronous and running on multiple platforms like android and other platforms. It is used in get and post requests; this is used as how we can send the get and post request in kotlin.

Recommended Articles

This is a guide to Kotlin HTTP Client. Here we discuss the introduction, requests, kotlin HTTP client configuration, methods, and FAQ. You may also have a look at the following articles to learn more –

1. Kotlin Web Framework
2. Kotlin Internal
3. Kotlin print
4. Kotlin Queue

The post Kotlin HTTP Client appeared first on EDUCBA.