package com.vogella.android.service.receiver;

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.URL;

import android.app.Activity;
import android.app.IntentService;
import android.content.Intent;
import android.net.Uri;
import android.os.Bundle;
import android.os.Environment;
import android.os.Message;
import android.os.Messenger;
import android.util.Log;

public class DownloadService extends IntentService {

    private int result = Activity.RESULT_CANCELED;
    public static final String URL = "urlpath";
    public static final String FILENAME = "filename";
    public static final String FILEPATH = "filepath";
    public static final String RESULT = "result";
    public static final String NOTIFICATION = "com.vogella.android.service.receiver";

    public DownloadService() {
        super("DownloadService");
    }

    // will be called asynchronously by Android
    @Override
    protected void onHandleIntent(Intent intent) {
        String urlPath = intent.getStringExtra(URL);
        String fileName = intent.getStringExtra(FILENAME);
        File output = new File(Environment.getExternalStorageDirectory(),
                fileName);
        if (output.exists()) {
            output.delete();
        }

        InputStream stream = null;
        FileOutputStream fos = null;
        try {

            URL url = new URL(urlPath);
            stream = url.openConnection().getInputStream();
            InputStreamReader reader = new InputStreamReader(stream);
            fos = new FileOutputStream(output.getPath());
            int next = -1;
            while ((next = reader.read()) != -1) {
                fos.write(next);
            }
            // successfully finished
            result = Activity.RESULT_OK;

        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            if (stream != null) {
                try {
                    stream.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if (fos != null) {
                try {
                    fos.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
        publishResults(output.getAbsolutePath(), result);
    }

    private void publishResults(String outputPath, int result) {
        Intent intent = new Intent(NOTIFICATION);
        intent.putExtra(FILEPATH, outputPath);
        intent.putExtra(RESULT, result);
        sendBroadcast(intent);
    }
}

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.vogella.android.service.receiver"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-sdk
        android:minSdkVersion="17"
        android:targetSdkVersion="18" />

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

    <application
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        <activity
            android:name="com.vogella.android.service.receiver.MainActivity"
            android:label="@string/app_name" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>

        <service android:name="com.vogella.android.service.receiver.DownloadService" >
        </service>
    </application>

</manifest>

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >

    <Button
        android:id="@+id/button1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:onClick="onClick"
        android:text="Download" />

    <LinearLayout
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" >

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Status: " />

        <TextView
            android:id="@+id/status"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Not started" />
    </LinearLayout>

</LinearLayout>

package com.vogella.android.service.receiver;

import android.app.Activity;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.os.Bundle;
import android.view.View;
import android.widget.TextView;
import android.widget.Toast;

public class MainActivity extends Activity {

    private TextView textView;
    private BroadcastReceiver receiver = new BroadcastReceiver() {

        @Override
        public void onReceive(Context context, Intent intent) {
            Bundle bundle = intent.getExtras();
            if (bundle != null) {
                String string = bundle.getString(DownloadService.FILEPATH);
                int resultCode = bundle.getInt(DownloadService.RESULT);
                if (resultCode == RESULT_OK) {
                    Toast.makeText(MainActivity.this,
                            "Download complete. Download URI: " + string,
                            Toast.LENGTH_LONG).show();
                    textView.setText("Download done");
                } else {
                    Toast.makeText(MainActivity.this, "Download failed",
                            Toast.LENGTH_LONG).show();
                    textView.setText("Download failed");
                }
            }
        }
    };

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        textView = (TextView) findViewById(R.id.status);
        

    }

    @Override
    protected void onResume() {
        super.onResume();
        registerReceiver(receiver, new IntentFilter(
                DownloadService.NOTIFICATION));
    }
    @Override
    protected void onPause() {
        super.onPause();
        unregisterReceiver(receiver);
    }

    public void onClick(View view) {

        Intent intent = new Intent(this, DownloadService.class);
        // add infos for the service which file to download and where to store
        intent.putExtra(DownloadService.FILENAME, "index.html");
        intent.putExtra(DownloadService.URL,
                "https://www.vogella.com/index.html");
        startService(intent);
        textView.setText("Service started");
    }
}

package com.vogella.android.localservice;

import android.app.Service;
import android.content.Intent;
import android.os.Binder;
import android.os.IBinder;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.Random;
public class LocalWordService extends Service {
    private final IBinder mBinder = new MyBinder();
    private List<String> resultList = new ArrayList<String>();
    private int counter = 1;

    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {
        addResultValues();
        return Service.START_NOT_STICKY;
    }

    @Override
    public IBinder onBind(Intent intent) {
        addResultValues();
        return mBinder;
    }

    public class MyBinder extends Binder {
        LocalWordService getService() {
            return LocalWordService.this;
        }
    }

    public List<String> getWordList() {
        return resultList;
    }

    private void addResultValues() {
        Random random = new Random();
        List<String> input = Arrays.asList("Linux", "Android","iPhone","Windows7" );
        resultList.add(input.get(random.nextInt(3)) + " " + counter++);
        if (counter == Integer.MAX_VALUE) {
            counter = 0;
        }
    }
}

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
          package="com.vogella.android.localservice">

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN"/>

                <category android:name="android.intent.category.LAUNCHER"/>
            </intent-filter>
        </activity>
        <service
            android:name=".LocalWordService"
            android:label="Word service" >
        </service>

    </application>

</manifest>

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
              android:layout_width="fill_parent"
              android:layout_height="fill_parent"
              android:orientation="vertical" >

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="horizontal"
        >
        <Button
            android:id="@+id/updateList"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:onClick="onClick"
            android:text="Update the list"
            >
        </Button>
        <Button
            android:id="@+id/triggerServiceUpdate"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:onClick="onClick"
            android:text="Trigger service"
            >
        </Button>

       
    </LinearLayout>

    <ListView
        android:id="@id/android:list"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" >
    </ListView>

</LinearLayout>

package com.vogella.android.localservice;

import android.app.ListActivity;
import android.content.ComponentName;
import android.content.Context;
import android.content.Intent;
import android.content.ServiceConnection;
import android.os.Bundle;
import android.os.IBinder;
import android.view.View;
import android.widget.ArrayAdapter;
import android.widget.Toast;

import java.util.ArrayList;
import java.util.List;

public class MainActivity extends ListActivity implements ServiceConnection {
    private LocalWordService s;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        wordList = new ArrayList<String>();
        adapter = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, android.R.id.text1, wordList);

        setListAdapter(adapter);
    }

    @Override
    protected void onResume() {
        super.onResume();
        Intent intent= new Intent(this, LocalWordService.class);
        bindService(intent, this, Context.BIND_AUTO_CREATE);
    }

    @Override
    protected void onPause() {
        super.onPause();
        unbindService(this);
    }

    private ArrayAdapter<String> adapter;
    private List<String> wordList;

    public void onClick(View view) {
        switch (view.getId()) {
            case R.id.updateList:
                if (s != null) {
                    Toast.makeText(this, "Number of elements" + s.getWordList().size(),
                            Toast.LENGTH_SHORT).show();
                    wordList.clear();
                    wordList.addAll(s.getWordList());
                    adapter.notifyDataSetChanged();
                }
                break;
            case R.id.triggerServiceUpdate:
                Intent service = new Intent(getApplicationContext(), LocalWordService.class);
                getApplicationContext().startService(service);
                break;
        }
    }

    @Override
    public void onServiceConnected(ComponentName name, IBinder binder) {
        LocalWordService.MyBinder b = (LocalWordService.MyBinder) binder;
        s = b.getService();
        Toast.makeText(MainActivity.this, "Connected", Toast.LENGTH_SHORT).show();
    }

    @Override
    public void onServiceDisconnected(ComponentName name) {
        s = null;
    }
}