Difficulty writing downloaded pdf file to android device

Question

I am downloading a pdf file from a web server using okhttp. The file appears to download correctly, and the file "Test.pdf" is created. The file size is listed as 0 however in the Device File Explorer in Android Studio.

Here is my callback code:

client.newCall(request).enqueue(object : Callback {

    override fun onFailure(call: Call, e: IOException) {
                    println("Failed")
                }

    override fun onResponse(call: Call, response: Response) {

                    println("Success!")

                    val file = File(filesDir, "Test.pdf")
                    println(response.body()!!.bytes().size)

                    file.outputStream().write(response.body()!!.bytes())
                    file.outputStream().flush()
                    file.outputStream().close()
                }
            })

The println statement shows the correct file size of 6MB. I am really unsure why the file is not writing to the device.

ice1000 · Answer 1 · 2018-05-05T19:51:32.710

3

Maybe there's a simpler way (also less efficient, but don't worry about small files, it's already very fast):

File(filesDir, "Test.pdf").writeBytes(URL("your url").readBytes())

writeBytes and readBytes are Kotlin stdlib extension functions.

edited May 05 '18 at 19:51

answered May 05 '18 at 19:46

ice1000

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This works thank you. I gave the answer credit to @zsmb13 because his answer was like a tutorial. – Scooter May 06 '18 at 02:34

score 1 · Accepted Answer · answered May 05 '18 at 20:25

You're opening a new OutputStream with every new call of the outputStream function. Instead, you can use just one:

val os = file.outputStream()
os.write(response.body()!!.bytes())
os.flush()
os.close()

And you might wanna wrap it in a use block instead of closing it yourself (and flushing it isn't necessary):

file.outputStream().use { os ->
    os.write(response.body()!!.bytes())
}

And if you only need to write a single ByteArray, the writeBytes method that was already suggested by @ice1000 does the above with even less code:

file.writeBytes(response.body()!!.bytes())

And while here, I'd perform a null check on the response body just to be safe:

val responseBytes = response.body()?.bytes()
if (responseBytes != null) {
    file.writeBytes(responseBytes)
} else {
    // Handle error somehow
}

Thank you for this very comprehensive answer. For whatever reason I was treating file.outputStream() like it was a singleton...rookie mistake. — Scooter, May 06 '18 at 02:36

Difficulty writing downloaded pdf file to android device

2 Answers2