--- title: "Instant JSON Attachment" canonical_url: "https://www.nutrient.io/guides/android/samples/instant-json-attachment-kotlin/" md_url: "https://www.nutrient.io/guides/android/samples/instant-json-attachment-kotlin.md" last_updated: "2026-05-15T19:10:04.916Z" description: "Export and import binary attachment data for image stamps in Instant JSON format." --- # Instant JSON Attachment Export and import binary attachment data for image stamps in Instant JSON format. [Get Started](https://www.nutrient.io/sdk/android/getting-started.md) [All Samples](https://www.nutrient.io/guides/android/samples.md) [Download](https://www.nutrient.io/guides/android/downloads.md) [Launch Demo](https://www.nutrient.io/demo/) --- ```kotlin /* * Copyright © 2022-2026 PSPDFKit GmbH. All rights reserved. * * The PSPDFKit Sample applications are licensed with a modified BSD license. * Please see License for details. This notice may not be removed from this file. */ package com.pspdfkit.catalog.examples.kotlin import android.content.Context import android.graphics.Bitmap import android.graphics.BitmapFactory import android.graphics.RectF import android.net.Uri import androidx.activity.viewModels import com.pspdfkit.annotations.StampAnnotation import com.pspdfkit.catalog.R import com.pspdfkit.catalog.SdkExample import com.pspdfkit.catalog.tasks.ExtractAssetTask import com.pspdfkit.configuration.activity.PdfActivityConfiguration import com.pspdfkit.document.PdfDocument import com.pspdfkit.document.providers.InputStreamDataProvider import com.pspdfkit.ui.PdfActivity import com.pspdfkit.ui.PdfActivityIntentBuilder import kotlinx.coroutines.runBlocking import java.io.File import java.io.FileOutputStream import java.io.FileWriter import java.io.IOException import java.io.InputStream import kotlin.getValue /** * Example showing how to export and import instant JSON attachment binaries. * */ class InstantJsonAttachmentExample(context: Context) : SdkExample( context, R.string.instantJsonAttachmentTitle, R.string.instantJsonAttachmentDescription, ) { override fun launchExample(context: Context, configuration: PdfActivityConfiguration.Builder) { // We turn off auto save to avoid saving redundant annotations. configuration.autosaveEnabled(false) // We use a custom utility class to extract the example document from the assets. ExtractAssetTask.extract(WELCOME_DOC, title, context) { documentFile -> // To start the `InstantJsonAttachmentExampleActivity` create a launch intent using the builder. val intent = PdfActivityIntentBuilder.fromUri(context, Uri.fromFile(documentFile)).configuration(configuration.build()).activityClass(InstantJsonAttachmentExampleActivity::class).build() context.startActivity(intent) } } } /** * This example activity subclasses [PdfActivity], and it demonstrates how to export and import instant JSON attachment binaries using * instant JSON Attachment APIs. */ class InstantJsonAttachmentExampleActivity : PdfActivity() { private val viewModel: AnnotationCreationViewModel by viewModels() override fun onDocumentLoaded(document: PdfDocument) { super.onDocumentLoaded(document) viewModel.createObjects { // Create a stamp annotation from an image bitmap. val annotationBitmap = getBitmapFromAsset() val stampAnnotation = StampAnnotation( 0, RectF(100f, (annotationBitmap.height / 2) + 100f, (annotationBitmap.width / 2) + 100f, 100f), annotationBitmap, ) // Add the stamp annotation to the document. runBlocking { document.annotationProvider.addAnnotationToPage(stampAnnotation) } // Export START. // Convert annotation to instant JSON. val jsonData = stampAnnotation.toInstantJson() // Prepare a file to store the image attachment. val tempBinaryAttachmentJsonFile = File.createTempFile("tmp_", "stampAnnotationBinaryJsonAttachment.jpeg") val outputStream = FileOutputStream(tempBinaryAttachmentJsonFile) // Write the Instant JSON attachment data to the file. if (stampAnnotation.hasBinaryInstantJsonAttachment()) { stampAnnotation.fetchBinaryInstantJsonAttachment(outputStream) } // Save the JSON data in a file. val tempJsonFile = File.createTempFile("tmp_", "stampAnnotationJson.txt") FileWriter(tempJsonFile).use { w -> w.write(jsonData) } // Export END. // Let's remove the annotation to try the import feature. runBlocking { document.annotationProvider.removeAnnotationFromPage(stampAnnotation) } // Import START. val anotherStampAnnotation = runBlocking { document.annotationProvider.createAnnotationFromInstantJson(jsonData) } anotherStampAnnotation.attachBinaryInstantJsonAttachment(FileDataProvider(tempBinaryAttachmentJsonFile), "image/jpeg") // Import END. } } /** Decodes bitmap from application's assets. */ private fun getBitmapFromAsset(): Bitmap = try { val inputStream = assets.open("images/android.png") BitmapFactory.decodeStream(inputStream) } catch (ioException: IOException) { throw RuntimeException("Error while trying to load PNG from assets: images/android.png", ioException) } } /** * Data provider that handles serving data from [File]. */ open class FileDataProvider(val file: File) : InputStreamDataProvider() { override fun getSize(): Long = file.length() override fun getUid(): String = file.canonicalPath override fun openInputStream(): InputStream = file.inputStream() override fun getTitle(): String? = file.nameWithoutExtension } ``` This code sample is an example that illustrates how to use our SDK. 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