Download PDF into your app in Kotlin for Android

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/*
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 *   Copyright © 2020-2025 PSPDFKit GmbH. All rights reserved.
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 *
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 *   The PSPDFKit Sample applications are licensed with a modified BSD license.
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 *   Please see License for details. This notice may not be removed from this file.
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 */
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package com.pspdfkit.catalog.examples.kotlin
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import android.content.Context
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import android.net.Uri
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import android.util.Log
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import androidx.appcompat.app.AlertDialog
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import androidx.fragment.app.FragmentActivity
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import com.pspdfkit.catalog.R
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import com.pspdfkit.catalog.SdkExample
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import com.pspdfkit.catalog.SdkExample.Companion.TAG
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import com.pspdfkit.configuration.activity.PdfActivityConfiguration
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import com.pspdfkit.document.download.DownloadJob
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import com.pspdfkit.document.download.DownloadProgressFragment
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import com.pspdfkit.document.download.DownloadRequest
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import com.pspdfkit.document.download.source.DownloadSource
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import com.pspdfkit.ui.PdfActivityIntentBuilder
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import java.io.File
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import java.io.IOException
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import java.io.InputStream
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import java.net.HttpURLConnection
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import java.net.MalformedURLException
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import java.net.URL
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import java.net.URLConnection
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/**
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 * This is an example showing how to use the [DownloadJob] to download a PDF document from the web.
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 */
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class DocumentDownloadExample(context: Context) : SdkExample(context, R.string.documentDownloadExampleTitle, R.string.documentDownloadExampleDescription) {
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    override fun launchExample(context: Context, configuration: PdfActivityConfiguration.Builder) {
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        // The web download source is a custom DownloadSource implemented below.
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        val source: WebDownloadSource = try {
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            // Try to parse the URL pointing to the PDF document. If an error occurs, log it and leave the example.
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            WebDownloadSource(URL("https://nutrient.io/downloads/case-study-box.pdf"))
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        } catch (e: MalformedURLException) {
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            Log.e(TAG, "Error while trying to parse the PDF Download URL.", e)
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            return
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        }
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        // Build a download request based on various input parameters. Provide the web source pointing to the document.
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        val request = DownloadRequest.Builder(context)
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            .source(source)
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            .outputFile(File(context.getDir("documents", Context.MODE_PRIVATE), "case-study-box.pdf"))
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            .overwriteExisting(true)
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            .build()
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        // This will initiate the download.
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        val job = DownloadJob.startDownload(request)
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        job.setProgressListener(object : DownloadJob.ProgressListenerAdapter() {
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            override fun onComplete(output: File) {
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                val intent = PdfActivityIntentBuilder.fromUri(context, Uri.fromFile(output))
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                    .configuration(configuration.build())
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                    .build()
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                context.startActivity(intent)
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            }
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            override fun onError(exception: Throwable) {
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                AlertDialog.Builder(context)
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                    .setMessage("There was an error downloading the example PDF file. For further information see Logcat.")
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                    .show()
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            }
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        })
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        val fragment = DownloadProgressFragment()
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        fragment.show((context as FragmentActivity).supportFragmentManager, "download-fragment")
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        fragment.job = job
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    }
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}
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/**
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 * This download source can be used to download a PDF document from the web.
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 */
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private class WebDownloadSource constructor(private val documentURL: URL) : DownloadSource {
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    /**
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     * The open method needs to return an [InputStream] that will provide the complete document.
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     */
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    @Throws(IOException::class)
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    override fun open(): InputStream {
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        val connection = documentURL.openConnection() as HttpURLConnection
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        connection.connect()
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        return connection.inputStream
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    }
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    /**
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     * If the length is available it can be returned here. This is optional, and can improve the reported download progress, since it will then contain
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     * a percentage of download.
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     */
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    override fun getLength(): Long {
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        var length = DownloadSource.UNKNOWN_DOWNLOAD_SIZE
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        // We try to estimate the download size using the content length header.
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        var urlConnection: URLConnection? = null
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        try {
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            urlConnection = documentURL.openConnection()
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            val contentLength = urlConnection.contentLength
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            if (contentLength != -1) {
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                length = contentLength.toLong()
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            }
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        } catch (e: IOException) {
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            Log.e(TAG, "Error while trying to parse the PDF Download URL.", e)
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        } finally {
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            (urlConnection as? HttpURLConnection)?.disconnect()
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        }
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        return length
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    }
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    override fun toString(): String {
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        return "WebDownloadSource{documentURL=$documentURL}"
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    }
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}