Upload images from Android Kotlin to Web Api .NET Core - second Example

Details
Written by: Stanko Milosev
Category: Android
Hits: 918
In this example I will upload pictures directly from builtIn gallery using this example.

Prepare virtual device like I already explained here.

Controller looks same as here.

In AndroidManifest.xml I need only retrofit permissions: 

<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
Api service: 
import com.google.gson.annotations.SerializedName
import okhttp3.MultipartBody
import retrofit2.Call
import retrofit2.http.Multipart
import retrofit2.http.POST
import retrofit2.http.Part

interface IWebApiService {
    @Multipart
    @POST("api/UploadPictures/UploadImage")
    fun uploadImage(
        @Part image: MultipartBody.Part?
    ): Call<UploadResponse>
}

data class UploadResponse(
    @SerializedName("message")
    val message: String
)
This time I will create Retrofit using dependency injection: 
import android.util.Log
import okhttp3.OkHttpClient
import retrofit2.Retrofit
import retrofit2.converter.gson.GsonConverterFactory
import java.security.cert.X509Certificate
import javax.net.ssl.SSLContext
import javax.net.ssl.TrustManager
import javax.net.ssl.X509TrustManager

internal class CreateRetrofitBuilder : ICreateRetrofitBuilder {
    override fun createRetrofitBuilder(baseUrl: String): Retrofit {
        return Retrofit.Builder()
            .baseUrl(baseUrl)
            .client(trustAllCertificates())
            .addConverterFactory(GsonConverterFactory.create())
            .build()
    }

    private fun trustAllCertificates(): OkHttpClient {
        val trustAllCerts = arrayOf<TrustManager>(object : X509TrustManager {
            override fun checkClientTrusted(chain: Array<out X509Certificate>?, authType: String?) {
                Log.i(MainActivity::class.simpleName, "checkClientTrusted")
            }

            override fun checkServerTrusted(chain: Array<out X509Certificate>?, authType: String?) {
                Log.i(MainActivity::class.simpleName, "checkServerTrusted")
            }

            override fun getAcceptedIssuers() = arrayOf<X509Certificate>()
        })
        val sslContext = SSLContext.getInstance("SSL")
        sslContext.init(null, trustAllCerts, java.security.SecureRandom())

// Create an ssl socket factory with our all-trusting manager
        val sslSocketFactory = sslContext.socketFactory

// connect to server
        return OkHttpClient.Builder()
            .sslSocketFactory(sslSocketFactory, trustAllCerts[0] as X509TrustManager)
            .hostnameVerifier { _, _ -> true }.build()
    }
}
Here notice that I am using "GsonConverterFactory" which means that Retrofit expects JSON anwer from the server, which is why I need UploadResponse class, and from server I will respond with: 
return Ok(new { message = "Image uploaded successfully." });
Otherwise I would receive error like: 

com.google.gson.stream.MalformedJsonException: Use JsonReader.setLenient(true) to accept malformed JSON at line 1 column 1 path $

Where ICreateRetrofitBuilder looks like: 

import retrofit2.Retrofit

interface ICreateRetrofitBuilder {
    fun createRetrofitBuilder(baseUrl: String): Retrofit
}
onResponse and onFailure I will also inject and use the like call backs: 
import android.app.AlertDialog
import retrofit2.Call
import retrofit2.Response

class UploadImageRetrofitCallBacks(private val alertDialogBuilder: AlertDialog.Builder) :
    IUploadImageRetrofitCallBacks {

    override fun onResponse(call: Call<UploadResponse>, response: Response<UploadResponse>) {
        if (!response.isSuccessful) {
            alertDialogBuilder.setMessage(response.errorBody()!!.charStream().readText())
                .setCancelable(false)
                .setNeutralButton("OK") { dialog, _ ->
                    dialog.dismiss()
                }

            val alert = alertDialogBuilder.create()
            alert.setTitle("Error")
            alert.show()
        } else {
            alertDialogBuilder.setMessage("Response: ${response.body()?.message.toString()}")
                .setCancelable(false)
                .setNeutralButton("OK") { dialog, _ ->
                    dialog.dismiss()
                }

            val alert = alertDialogBuilder.create()
            alert.setTitle("Success")
            alert.show()
        }
    }

    override fun onFailure(call: Call<UploadResponse>, t: Throwable) {
        alertDialogBuilder.setMessage(t.message)
            .setCancelable(false)
            .setNeutralButton("OK") { dialog, _ ->
                dialog.dismiss()
            }

        val alert = alertDialogBuilder.create()
        alert.setTitle("Error")
        alert.show()
    }
}
Where interface looks like: 
import retrofit2.Call
import retrofit2.Response

interface IUploadImageRetrofitCallBacks {
    fun onResponse(call: Call<UploadResponse>, response: Response<UploadResponse>)
    fun onFailure(call: Call<UploadResponse>, t: Throwable)
}
Upload image: 
import android.content.Context
import android.net.Uri
import okhttp3.MediaType.Companion.toMediaTypeOrNull
import okhttp3.MultipartBody
import okhttp3.RequestBody.Companion.toRequestBody
import retrofit2.Call
import retrofit2.Callback
import retrofit2.Response

class UploadImageRetrofit(private val uploadImageRetrofitCallBacks: IUploadImageRetrofitCallBacks, private val webApiService: IWebApiService) {
    fun uploadImage(imgUri: Uri, context: Context): String? {

        val inputStream = context.contentResolver.openInputStream(imgUri)
        val mediaType = context.contentResolver.getType(imgUri)?.toMediaTypeOrNull()
        val requestFile = inputStream?.use {
            it.readBytes().toRequestBody(mediaType)
        }
        val imagePart: MultipartBody.Part? = requestFile?.let {
            MultipartBody.Part.createFormData("image", "image.jpg", it)
        }

        val webApiRequest = webApiService.uploadImage(imagePart)

        webApiRequest.enqueue(object : Callback<UploadResponse> {
            override fun onResponse(call: Call<UploadResponse>, response: Response<UploadResponse>) {
                uploadImageRetrofitCallBacks.onResponse(call, response)
            }

            override fun onFailure(call: Call<UploadResponse>, t: Throwable) {
                uploadImageRetrofitCallBacks.onFailure(call, t)
            }
        })

        return null
    }
}
At the end, MainActivity looks like this: 
import android.app.AlertDialog
import android.os.Bundle
import android.view.View
import androidx.activity.result.contract.ActivityResultContracts
import androidx.appcompat.app.AppCompatActivity

class MainActivity : AppCompatActivity() {
    private lateinit var uploadImage: UploadImageRetrofit

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

        uploadImage = UploadImageRetrofit(
            UploadImageRetrofitCallBacks(AlertDialog.Builder(this@MainActivity)),
            CreateRetrofitBuilder().createRetrofitBuilder("https://10.0.2.2:7181/")
                .create(IWebApiService::class.java)
        )
    }

    private val galleryLauncher =
        this.registerForActivityResult(ActivityResultContracts.GetMultipleContents()) { images ->
            images.forEach { imgUri ->
                uploadImage.uploadImage(imgUri, this)
            }
        }

    fun onOpenGalleryAndUploadButtonClick(view: View) {
        galleryLauncher.launch("image/*")
    }
}
Download from here.

Upload images from Android Kotlin to Web Api .NET Core - first Example

Details
Written by: Stanko Milosev
Category: Android
Hits: 1378

First problem, if you want to upload hardcoded path to the image like /sdcard/Download/IMG_20240120_133805.jpg, you will need external storage permission

Upload image to virtual device like I already wrote here

Here is ASP.NET Web Api Core example

In order to work in all versions in AndroidManifest.xml I have added: 
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" android:maxSdkVersion="28" />
<uses-permission android:name="android.permission.MANAGE_EXTERNAL_STORAGE" />
Please notice if you use MANAGE_EXTERNAL_STORAGE most probably you app will be rejected on play store

To check storage permission for all versions of Android I have used following code: 

@RequiresApi(Build.VERSION_CODES.R)
fun checkLocalStoragePermission() {
	if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.R) {
		if (!Environment.isExternalStorageManager()) {
			val uri = Uri.parse("package:${BuildConfig.APPLICATION_ID}")
			startActivity(
				Intent(
					Settings.ACTION_MANAGE_APP_ALL_FILES_ACCESS_PERMISSION,
					uri
				)
			)
		}
	}
}
In app\build.gradle.kts I have added buildConfig = true, 
buildFeatures {
	buildConfig = true
}
so that piece of code 
val uri = Uri.parse("package:${BuildConfig.APPLICATION_ID}")
works


Also, for retrofit I will need permission: 

<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />

In app\build.gradle.kts I have added retrofit: 

implementation( "com.squareup.retrofit2:retrofit:2.9.0")
implementation("com.squareup.okhttp3:okhttp:4.12.0")
implementation("com.squareup.retrofit2:converter-scalars:2.9.0")
implementation("com.squareup.retrofit2:converter-gson:2.9.0")

Then I have added WebApiService interface: 

import okhttp3.MultipartBody
import retrofit2.Call
import retrofit2.http.Multipart
import retrofit2.http.POST
import retrofit2.http.Part

interface WebApiService {
    @Multipart
    @POST("api/UploadPictures/UploadImage")
    fun uploadImage(
        @Part image: MultipartBody.Part?
    ): Call<UploadResponse>
}

data class UploadResponse(
    @SerializedName("message")
    val message: String
)
Retrofit is almost the same as I already explained here, except the post method: 
val imageFile = File(imagePath)
val requestBody = imageFile.asRequestBody("image/*".toMediaTypeOrNull())
val imagePart = MultipartBody.Part.createFormData("image", imageFile.name, requestBody)

val apiService = retrofit.create(WebApiService::class.java)
val webApiRequest = apiService.uploadImage(imagePart)
Here how the whole file looks like: 
import android.app.AlertDialog
import android.util.Log
import okhttp3.MediaType.Companion.toMediaTypeOrNull
import okhttp3.MultipartBody
import okhttp3.OkHttpClient
import okhttp3.RequestBody.Companion.asRequestBody
import retrofit2.Call
import retrofit2.Callback
import retrofit2.Response
import retrofit2.Retrofit
import retrofit2.converter.gson.GsonConverterFactory
import java.io.File
import java.security.cert.X509Certificate
import javax.net.ssl.SSLContext
import javax.net.ssl.TrustManager
import javax.net.ssl.X509TrustManager

class UploadImageRetrofit {
    fun uploadImage(imagePath: String, alertDialogBuilder: AlertDialog.Builder): String? {

        val trustAllCerts = arrayOf<TrustManager>(object : X509TrustManager {
            override fun checkClientTrusted(chain: Array<out X509Certificate>?, authType: String?) {
                Log.i(MainActivity::class.simpleName, "checkClientTrusted")
            }

            override fun checkServerTrusted(chain: Array<out X509Certificate>?, authType: String?) {
                Log.i(MainActivity::class.simpleName, "checkServerTrusted")
            }

            override fun getAcceptedIssuers() = arrayOf<X509Certificate>()
        })
        val sslContext = SSLContext.getInstance("SSL")
        sslContext.init(null, trustAllCerts, java.security.SecureRandom())

// Create an ssl socket factory with our all-trusting manager
        val sslSocketFactory = sslContext.socketFactory

// connect to server
        val client = OkHttpClient.Builder()
            .sslSocketFactory(sslSocketFactory, trustAllCerts[0] as X509TrustManager)
            .hostnameVerifier { _, _ -> true }.build()


        val retrofit = Retrofit.Builder()
            .baseUrl("https://10.0.2.2:7181/")
            .client(client)
            .addConverterFactory(GsonConverterFactory.create())
            .build()

        val imageFile = File(imagePath)
        val requestBody = imageFile.asRequestBody("image/*".toMediaTypeOrNull())
        val imagePart = MultipartBody.Part.createFormData("image", imageFile.name, requestBody)

        val apiService = retrofit.create(WebApiService::class.java)
        val webApiRequest = apiService.uploadImage(imagePart)

        webApiRequest.enqueue(object : Callback<UploadResponse> {
            override fun onResponse(call: Call<UploadResponse>, response: Response<UploadResponse>) {

                if (!response.isSuccessful) {
                    alertDialogBuilder.setMessage(response.errorBody()!!.charStream().readText())
                        .setCancelable(false)
                        .setNeutralButton("OK") { dialog, _ ->
                            dialog.dismiss()
                        }

                    val alert = alertDialogBuilder.create()
                    alert.setTitle("Error")
                    alert.show()
                } else {
                    alertDialogBuilder.setMessage("Response: ${response.body()?.message.toString()}")
                        .setCancelable(false)
                        .setNeutralButton("OK") { dialog, _ ->
                            dialog.dismiss()
                        }

                    val alert = alertDialogBuilder.create()
                    alert.setTitle("Success")
                    alert.show()
                }
            }

            override fun onFailure(call: Call<UploadResponse>, t: Throwable) {
                alertDialogBuilder.setMessage(t.message)
                    .setCancelable(false)
                    .setNeutralButton("OK") { dialog, _ ->
                        dialog.dismiss()
                    }

                val alert = alertDialogBuilder.create()
                alert.setTitle("Error")
                alert.show()
            }

        })

        return null
    }
}

MainActivity.kt: 

import android.app.AlertDialog
import android.content.Intent
import android.net.Uri
import android.os.Build
import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.os.Environment
import android.provider.Settings
import android.view.View
import androidx.annotation.RequiresApi

class MainActivity : AppCompatActivity() {
    @RequiresApi(Build.VERSION_CODES.R)
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        checkLocalStoragePermission()
    }

    fun onUploadImageButtonClick(view: View) {
        val uploadImageRetrofit = UploadImageRetrofit()
        val alertDialogBuilder = AlertDialog.Builder(this@MainActivity)
        uploadImageRetrofit.uploadImage("/sdcard/Download/IMG_20240120_133805.jpg", alertDialogBuilder)
    }

    @RequiresApi(Build.VERSION_CODES.R)
    fun checkLocalStoragePermission() {
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.R) {
            if (!Environment.isExternalStorageManager()) {
                val uri = Uri.parse("package:${BuildConfig.APPLICATION_ID}")
                startActivity(
                    Intent(
                        Settings.ACTION_MANAGE_APP_ALL_FILES_ACCESS_PERMISSION,
                        uri
                    )
                )
            }
        }
    }
}
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---

Web API .Net Core controller: 
using Microsoft.AspNetCore.Mvc;

namespace UploadPictures.Controllers;

[ApiController]
[Route("api/[controller]")]
public class UploadPicturesController : Controller
{

    private readonly string _uploadPath = Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.ApplicationData), "UploadPictures", "uploads");

    [HttpPost]
    [Route("UploadImage")]
    public async Task<IActionResult> UploadImage()
    {
        try
        {
            if (!Request.HasFormContentType)
            {
                return BadRequest("Invalid content type. Must be multipart/form-data.");
            }

            var form = await Request.ReadFormAsync();
            var file = form.Files.FirstOrDefault();

            if (file == null)
            {
                return BadRequest("No image file found in the request.");
            }

            // Generate a unique filename
            var filename = Path.GetRandomFileName() + Path.GetExtension(file.FileName);
            var filePath = Path.Combine(_uploadPath, filename);

            // Create the upload directory if it doesn't exist
            Directory.CreateDirectory(_uploadPath);

            // Save the uploaded file
            await using (var stream = new FileStream(filePath, FileMode.Create))
            {
                await file.CopyToAsync(stream);
            }
            return Ok(new { message = "Image uploaded successfully." });
        }
        catch (Exception ex)
        {
            // Log the error for debugging
            Console.WriteLine(ex.ToString());
            return StatusCode(500, "Internal server error.");
        }
    }
}
Download Visual Studio .NET Core example from here

Upload images to virtual device

Details
Written by: Stanko Milosev
Category: Android
Hits: 918
Open device in Device explorer:

And click on button upload

Select images from local storage

Details
Written by: Stanko Milosev
Category: Android
Hits: 914
My example how to select images from local storage: 
class MainActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
    }

    private val galleryLauncher =
        this.registerForActivityResult(ActivityResultContracts.GetMultipleContents()) { images ->
            for (image in images) {
                println(image.path)
            }
        }

    private fun openGallery() {
        galleryLauncher.launch("image/*")
    }

    fun onButtonClick(view: View) {
        openGallery();
    }
}
  1. Binding
  2. Get data from Activity
  3. Simple MVVM example in Kotlin
  4. Mock context

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