Monday, January 21, 2019

android kotlin - WorkManager example

MainActivity.kt 

package com.cfsuman.jetpack

import android.content.Context
import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.util.Log
import kotlinx.android.synthetic.main.activity_main.*
import android.graphics.BitmapFactory
import java.io.BufferedInputStream
import java.io.IOException
import java.net.HttpURLConnection
import android.graphics.Bitmap
import androidx.work.*


class MainActivity : AppCompatActivity() {

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

        // Download image
        btnDownload.setOnClickListener{
            // Create an one time work request
            val downloadImageWork = OneTimeWorkRequest.Builder(DownloadImageWorker::class.java).build()
            // Enqueue the work
            WorkManager.getInstance().enqueue((downloadImageWork))
        }


        // Display the downloaded image
        btnShow.setOnClickListener{
            if (countSavedBitmap>0){
                imageView.setImageURI(nameToUri(savedBitmapList[countSavedBitmap-1]))
                textView.text = savedBitmapList[savedBitmapList.count()-1]
            }else
            {
                toast("No downloaded image found")
            }
        }
    }
}


// Worker class to download image
class DownloadImageWorker(context:Context, params: WorkerParameters): Worker(context,params){
    override fun doWork(): Result {
        // Do the work here
        val url = stringToURL("https://www.freeimageslive.com/galleries/buildings/china/pics/nature_water3978.jpg")

        // IMPORTANT - Put internet permission on manifest file
        var connection: HttpURLConnection? = null

        try {
            // Initialize a new http url connection
            connection = url?.openConnection() as HttpURLConnection

            // Connect the http url connection
            connection.connect()

            // Get the input stream from http url connection
            val inputStream = connection.getInputStream()

            // Initialize a new BufferedInputStream from InputStream
            val bufferedInputStream = BufferedInputStream(inputStream)

            // Convert BufferedInputStream to Bitmap object

            // Return the downloaded bitmap
            val bmp:Bitmap? = BitmapFactory.decodeStream(bufferedInputStream)
            bmp?.saveToInternalStorage(applicationContext)

            Log.d("download","success")
            return Result.success()

        } catch (e: IOException) {
            e.printStackTrace()
            Log.d("download",e.toString())

        } finally {
            // Disconnect the http url connection
            connection?.disconnect()
        }
        Log.d("download","failed")
        return Result.failure()
    }
}
xBitmap.kt 

package com.cfsuman.jetpack

import android.content.Context
import android.content.ContextWrapper
import android.graphics.Bitmap
import android.net.Uri
import android.widget.Toast
import java.io.File
import java.io.FileOutputStream
import java.io.IOException
import java.io.OutputStream
import java.net.MalformedURLException
import java.net.URL
import java.util.*


// Extension function to save bitmap in internal storage
fun Bitmap.saveToInternalStorage(context: Context): Uri {
    // Get the context wrapper instance
    val wrapper = ContextWrapper(context)

    // Initializing a new file
    // The bellow line return a directory in internal storage
    var file = wrapper.getDir("images", Context.MODE_PRIVATE)


    // Create a file to save the image
    file = File(file, "${UUID.randomUUID()}.png")

    try {
        // Get the file output stream
        val stream: OutputStream = FileOutputStream(file)

        // Compress bitmap
        this.compress(Bitmap.CompressFormat.PNG, 100, stream)

        // Flush the stream
        stream.flush()

        // Close stream
        stream.close()
    } catch (e: IOException){ // Catch the exception
        e.printStackTrace()
    }

    // Return the saved image uri
    return Uri.parse(file.absolutePath)
}


// Extension function to count internal storage images
val Context.countSavedBitmap:Int
    get(){
        val wrapper = ContextWrapper(this)
        val file = wrapper.getDir("images", Context.MODE_PRIVATE)
        val length = file.list().size
        return length
    }


// Extension function to get internal storage images list
val Context.savedBitmapList:MutableList<String>
get(){
    val wrapper = ContextWrapper(this)
    val file = wrapper.getDir("images", Context.MODE_PRIVATE)
    val list = file.list().asList().toMutableList()
    return list
}



fun Context.nameToUri(name:String):Uri{
    val wrapper = ContextWrapper(this)

    // Initializing a new file
    // The bellow line return a directory in internal storage
    var file = wrapper.getDir("images", Context.MODE_PRIVATE)


    // Create a file to save the image
    file = File(file, name)

    val uri = Uri.fromFile(file)

    return uri
}


// Custom method to convert string to url
fun stringToURL(urlString: String): URL? {
    try {
        return URL(urlString)
    } catch (e: MalformedURLException) {
        e.printStackTrace()
    }

    return null
}


fun Context.toast(message:String)=
    Toast.makeText(this,message, Toast.LENGTH_SHORT).show()
activity_main.xml 

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout
        xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:tools="http://schemas.android.com/tools"
        xmlns:app="http://schemas.android.com/apk/res-auto"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:id="@+id/rootLayout"
        tools:context=".MainActivity"
        android:background="#fdfdfc">
    <Button
            android:text="Download Image"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:id="@+id/btnDownload"
            android:layout_marginTop="8dp" 
            app:layout_constraintTop_toTopOf="parent" 
            android:layout_marginEnd="8dp"
            app:layout_constraintEnd_toEndOf="parent" 
            android:layout_marginStart="8dp"
            app:layout_constraintStart_toStartOf="parent" 
            app:layout_constraintHorizontal_bias="0.498"/>
    <Button
            android:text="Show Image"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:id="@+id/btnShow"
            android:layout_marginTop="8dp"
            app:layout_constraintTop_toBottomOf="@+id/btnDownload"
            app:layout_constraintEnd_toEndOf="parent"
            android:layout_marginEnd="8dp"
            app:layout_constraintStart_toStartOf="parent"
            android:layout_marginStart="8dp"/>
    <ImageView
            android:layout_width="0dp"
            android:layout_height="0dp" 
            tools:srcCompat="@tools:sample/avatars"
            android:id="@+id/imageView"
            app:layout_constraintEnd_toEndOf="parent"
            android:layout_marginEnd="8dp" 
            app:layout_constraintStart_toStartOf="parent"
            android:layout_marginStart="8dp"
            app:layout_constraintHorizontal_bias="0.0" 
            android:layout_marginTop="8dp"
            app:layout_constraintTop_toBottomOf="@+id/textView" 
            android:layout_marginBottom="8dp"
            app:layout_constraintBottom_toBottomOf="parent"/>
    <TextView
            android:text="Image URI"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:id="@+id/textView"
            android:layout_marginTop="8dp"
            app:layout_constraintTop_toBottomOf="@+id/btnShow" 
            app:layout_constraintEnd_toEndOf="parent"
            android:layout_marginEnd="8dp"
            app:layout_constraintStart_toStartOf="parent"
            android:layout_marginStart="8dp"/>
</androidx.constraintlayout.widget.ConstraintLayout>
gradle dependencies 

// WorkManager
def work_version = "1.0.0-beta02"
implementation "android.arch.work:work-runtime:$work_version"
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