Retrofit 2 Kotlin Example, Imgur upload image example.

ImgurApiService.kt

package com.your.packagename

import com.txwstudio.app.roadreport.json.imgurupload.ImgurUploadJson
import okhttp3.MultipartBody
import okhttp3.OkHttpClient
import retrofit2.Call
import retrofit2.Retrofit
import retrofit2.converter.gson.GsonConverterFactory
import retrofit2.http.Header
import retrofit2.http.Multipart
import retrofit2.http.POST
import retrofit2.http.Part
import java.util.concurrent.TimeUnit

private const val BASE_URL = "https://api.imgur.com"

private val okHttpClient = OkHttpClient.Builder()
    .connectTimeout(15, TimeUnit.SECONDS)
    .writeTimeout(30, TimeUnit.SECONDS)
    .readTimeout(15, TimeUnit.SECONDS)
    .build()

private val retrofit = Retrofit.Builder().client(okHttpClient)
    .addConverterFactory(GsonConverterFactory.create())
    .baseUrl(BASE_URL)
    .build()

interface ImgurApiService {

    /**
     * Imgur upload API.
     *
     * @param clientId Imgur Client ID
     * @param image The image want to upload
     */
    @Multipart
    @POST("/3/upload")
    fun postImage(
        @Header("Authorization") clientId: String,
        @Part image: MultipartBody.Part
    ):
            Call<ImgurUploadJson>
}

object ImgurApi {
    val retrofitService: ImgurApiService by lazy {
        retrofit.create(ImgurApiService::class.java)
    }
}

ImgurUplaodJson.kt

package com.your.packagename

import com.google.gson.annotations.SerializedName

data class ImgurUploadJson(
    @SerializedName("data") val data: Data?,
    @SerializedName("status") val status: Int?,
    @SerializedName("success") val success: Boolean?
) {
    fun getImageLink(): String? {
        return data?.link
    }
}


// ----------
// Another kt file
// ----------
package com.your.packagename

data class Data(
    val account_id: Int,
    val account_url: String,
    val ad_type: Any,
    val ad_url: Any,
    val animated: Boolean,
    val bandwidth: Int,
    val datetime: Int,
    val deletehash: String,
    val description: Any,
    val favorite: Boolean,
    val has_sound: Boolean,
    val height: Int,
    val hls: String,
    val id: String,
    val in_gallery: Boolean,
    val in_most_viral: Boolean,
    val is_ad: Boolean,
    val link: String,
    val mp4: String,
    val name: String,
    val nsfw: Any,
    val section: Any,
    val size: Int,
    val tags: List<Any>,
    val title: Any,
    val type: String,
    val views: Int,
    val vote: Any,
    val width: Int
)

WeatherViewModel.kt

private fun sendImageAndGetLink(body: MultipartBody.Part) {
  
        val imgurApi = ImgurApi.retrofitService.postImage("YOUR_CLIENT_ID_HERE", body)
  
        imgurApi.enqueue(object : Callback<ImgurUploadJson> {
            override fun onResponse(call: Call<ImgurUploadJson>, response: Response<ImgurUploadJson>) {
                binding.progressbarEventEditorImageProgress.visibility = View.GONE
                if (response.isSuccessful) {
                    // Prevent "Error 429 Too many requests", when run into it, the link will be null.
                    if (response.body()?.getImageLink() == null || response.body()?.getImageLink() == "null") {
                        eventEditorViewModel.imageUrl.value = ""
                        Util().snackBarShort(
                                requireActivity().findViewById(R.id.coordinatorLayout_eventEditor),
                                getString(R.string.accidentEvent_imageUploadFail_server)
                        )
                    } else {
                        Log.i("TESTTT", "圖片連結為 " + response.body()?.getImageLink())
                        eventEditorViewModel.imageUrl.value = response.body()?.getImageLink()
                    }
                } else {
                    Util().snackBarShort(
                            requireActivity().findViewById(R.id.coordinatorLayout_eventEditor),
                            "Imgur Error ${response.code().toString()}"
                    )
                }
            }

            override fun onFailure(call: Call<ImgurUploadJson>, t: Throwable) {
                binding.progressbarEventEditorImageProgress.visibility = View.GONE

                val errMsg: String = when (t) {
                    is SocketTimeoutException -> {
                        getString(R.string.accidentEvent_imageUploadFail_timeout)
                    }
                    is IOException -> {
                        getString(R.string.accidentEvent_imageUploadFail_IO)
                    }
                    else -> getString(R.string.accidentEvent_imageUploadFail_unknown)
                }
                Util().snackBarShort(
                        requireActivity().findViewById(R.id.coordinatorLayout_eventEditor),
                        errMsg
                )
            }
        })
}