android retrofit2

https://square.github.io/retrofit/

Retrofit

libs.versions.toml

[versions]
....
retrofit2 = "2.11.0"
kotlinx-serialization-json = "1.6.3"

[libraries]
....
retrofit2 = { group = "com.squareup.retrofit2", name = "retrofit", version.ref = "retrofit2" }
retrofit2-converter-gson = { group = "com.squareup.retrofit2", name = "converter-gson", version.ref = "retrofit2" }
retrofit2-converter-jackson = { group = "com.squareup.retrofit2", name = "converter-jackson", version.ref = "retrofit2" }
kotlinx-serialization-json = { group = "org.jetbrains.kotlinx", name = "kotlinx-serialization-json", version.ref = "kotlinx-serialization-json" }

....

build.gradle.kts(Module)

dependencies {
    ....
    implementation(libs.retrofit2)
    implementation(libs.retrofit2.converter.gson)
    implementation(libs.retrofit2.converter.jackson)
    implementation(libs.kotlinx.serialization.json)
    ....
}

data class(dto) > Service(interface) > Builder instance 순서

https://koreanjson.com/

Korean JSON

위 api사이트에서 user목록을 읽어 본다.

User.kts(DTO)

package com.dbility.myretrofi

import com.fasterxml.jackson.annotation.JsonProperty
import kotlinx.serialization.Serializable

@Serializable
data class User(
    @JsonProperty("id") val id : Long,
    @JsonProperty("name") val name : String,
    @JsonProperty("username") val userName : String,
    @JsonProperty("email") val email : String,
    @JsonProperty("phone") val phone : String?,
    @JsonProperty("website") val website : String?,
    @JsonProperty("province") val province : String?,
    @JsonProperty("city") val city : String?,
    @JsonProperty("district") val district : String?,
    @JsonProperty("street") val street : String?,
    @JsonProperty("zipcode") val zipcode : String?,
    @JsonProperty("createdAt") val createdAt : String,
    @JsonProperty("updatedAt") val updatedAt : String?
)

UserService(interface)

package com.dbility.myretrofi

import retrofit2.Call
import retrofit2.http.GET
import retrofit2.http.Path

interface UserService {

    @GET("users/{id}")
    fun getUsers(@Path("id") id:String): Call<List<User>>
}

package com.dbility.myretrofi

import android.os.Bundle
import android.util.Log
import android.widget.ArrayAdapter
import android.widget.TextView
import android.widget.Toast
import androidx.activity.enableEdgeToEdge
import androidx.appcompat.app.AppCompatActivity
import androidx.core.view.ViewCompat
import androidx.core.view.WindowInsetsCompat
import com.dbility.myretrofi.databinding.ActivityMainBinding
import retrofit2.Call
import retrofit2.Callback
import retrofit2.Response
import retrofit2.Retrofit
import retrofit2.converter.jackson.JacksonConverterFactory

class MainActivity : AppCompatActivity() {

    companion object {
        private const val TAG: String = "MainActivity"
    }

    private val binding by lazy {
        ActivityMainBinding.inflate(layoutInflater)
    }

    private val retrofit by lazy {
        Retrofit.Builder()
            .baseUrl("https://koreanjson.com/")
            .addConverterFactory(JacksonConverterFactory.create())
            .build()
    }

    private val userService by lazy {
        retrofit.create(UserService::class.java)
    }

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        enableEdgeToEdge()
        setContentView(binding.root)
        ViewCompat.setOnApplyWindowInsetsListener(binding.root) { v, insets ->
            val systemBars = insets.getInsets(WindowInsetsCompat.Type.systemBars())
            v.setPadding(systemBars.left, systemBars.top, systemBars.right, systemBars.bottom)
            insets
        }

        with(binding) {
            activityMainButtonGet.setOnClickListener {
                userService.getUsers("").enqueue(object : Callback<List<User>> {
                    override fun onResponse(
                        call: Call<List<User>>,
                        response: Response<List<User>>
                    ) {
                        if (response.isSuccessful.not()) {
                            Log.d(TAG, "Response Failure")
                            Toast.makeText(
                                this@MainActivity,
                                "Response Failure",
                                Toast.LENGTH_SHORT
                            ).show()
                            return
                        }
                        response.body()?.let {
                            Log.d(TAG,it.toString())                            
                        } ?: run {
                            Log.d(TAG, "response body is empty")
                        }
                    }

                    override fun onFailure(call: Call<List<User>>, throwable: Throwable) {
                        Log.d(TAG, throwable.toString())
                    }
                })
            }
        }

    }
}