How can I get http request in Kotlin (Android Studio)

Question

I have problem with getting HTTP request on kotlin. I have a simple server written python and I want to write a client in kotlin (Android studio). I want to get a request than curl (curl localhost:8080/state). Can someone help me pls?

server:

import enum

from bottle import route, run, template


class Signs(enum.Enum):
    SCRISSORS = enum.auto()
    STONE = enum.auto()
    PAPER = enum.auto()
    NOTHING = enum.auto()


board_state = [Signs.NOTHING, Signs.NOTHING]

final_states = {
    (Signs.STONE, Signs.SCRISSORS): "Player 1 wins",
    (Signs.SCRISSORS, Signs.STONE): "Player 2 wins",
    (Signs.PAPER, Signs.STONE): "Player 1 wins",
    (Signs.STONE, Signs.PAPER): "Player 2 wins",
    (Signs.SCRISSORS, Signs.PAPER): "Player 1 wins",
    (Signs.PAPER, Signs.SCRISSORS): "Player 2 wins",
}


@route('/<raw_player>/<raw_sign>')
def play(raw_player, raw_sign):
    try:
        player = int(raw_player) - 1
    except:
        return "Invalid player, expecting int"

    try:
        sign = Signs[raw_sign.upper()]
    except:
        return "Invalid sign"

    if not player in {0, 1}:
        return "Invalid player number"

    board_state[player] = sign
    return "OK\n"


@route('/state')
def state():
    if board_state[0] is Signs.NOTHING and board_state[1] is Signs.NOTHING:
        return "Nobody played\n"

    if board_state[0] is Signs.NOTHING:
        return "Waiting for player 1\n"

    if board_state[1] is Signs.NOTHING:
        return "Waiting for player 2\n"

    if board_state[0] is board_state[1]:
        return "Draw\n"

    return final_states[tuple(board_state)] + "\n"


@route('/reset')
def reset():
    board_state[0] = Signs.NOTHING
    board_state[1] = Signs.NOTHING
    return "OK\n"


run(host='localhost', port=8080)

client:

package com.example.barcang

import android.content.Intent
import android.os.Bundle
import android.widget.ImageButton
import androidx.appcompat.app.AppCompatActivity
import java.util.*

class kmnActivity : AppCompatActivity() {
    val EXTRA_TEXT = "com.example.application.example.EXTRA_TEXT"
    var uuid = UUID.randomUUID().toString()

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_kmn)

        val kamenButton = findViewById<ImageButton>(R.id.kamen)
        val papierButton = findViewById<ImageButton>(R.id.papier)
        val nozniceButton = findViewById<ImageButton>(R.id.noznice)

        kamenButton.setOnClickListener {
            //here i want get 'curl localhost:8080/1/stone'
            openRollActivity()
        }

        papierButton.setOnClickListener {
            //here i want get 'curl localhost:8080/1/paper'
            openRollActivity()
        }

        nozniceButton.setOnClickListener {
            //here i want get 'curl localhost:8080/1/scrissors
            openRollActivity()
        }
    }

    fun openRollActivity() {
        val intent = Intent(this@kmnActivity, rollActivity::class.java)
        intent.putExtra("id", uuid)
        startActivity(intent)
    }
}

if i click on button papierButton(translate paperButton) i want get http request on my server (curl localhost:8080/1/paper)

Answer 1

One way is to use ktor http client .

Include it in your dependencies. ie build.gradle.kts :

implementation("io.ktor:ktor-client-core:1.3.2")
implementation("io.ktor:ktor-client-android:1.3.2")

Use it in your project:

runBlocking {
    val client = HttpClient() {
        engine {
            // this is an example how you can tweak client options
            followRedirects = true
        }
    }
    val response = client.get<String>("http://localhost:8080/1/stone")
}

In the above example I asked for the response as a string, but you could either get an HTTP response, or deserialised object . Refer to ktor's documentation for more examples.