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IntentServices
5:40In this video we’ll learn about IntentServices and refactor our app to use one!
Using a service to handle intense
one at a time on a separate thread
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like we've done with our download service,
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is one of the most common ways that
developers make use of services.
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In fact, it's so common that
Android created a special class
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to make writing a service like this,
a lot easier.
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And that class is intent service.
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Let's see how we can refactor our
code to use an intent service.
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Let's start by creating a new class for
our intent service and
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let's name it DownloadIntentService.
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Then let's make it extend IntentService,
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and let's use Alt+Enter to
implement the required method.
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This onHandleIntentMethod is
where we'll handle our intent.
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Now before we forget it,
Let's head over to our AndroidManifest and
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declare our new service.
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After you create an application
component like a service or
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activity, it's usually a good idea to
add it to your manifest right away.
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It's super easy to forget about and
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it will definitely throw an error,
trust me I've tested it.
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We'll need to declare it just like
we did with download service,
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which also gives me an opportunity to show
off one of my favorite keyboard shortcuts.
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Place your cursor anywhere on
the download service line and
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hit command or control D,
which stands for duplicate.
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Now we just have to change download
service to download intense service and
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we're done.
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But it looks like we
need to add a constructor
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to our download intense service.
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Back in our intense service,
let's add that constructor, public
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DownloadIntentService.
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And inside the constructor,
lets add a call to super
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and pass in DownloadIntentService
as a string.
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This sets
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the name of the thread where our
intense service will be doing its work.
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Then, let's add a call to
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setIntentRedelivery and pass in true.
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By default,
an intent service will use start sticky.
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But we needed to use
start redeliver intent.
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This method lets us change on
start commands return value for
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our intent service,
even though we can't see it.
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All right, now let's copy our download
song method from download handler.
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And paste it in the bottom of
our IntentService class and
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create our TAG constant.
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Get SimpleName.
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And I'll get rid of this
extra space up here.
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Then and the On handle intent method.
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Let's retrieve our song from the intent
and pass it to the download song method.
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String_song = intent.getStringExtra
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MainActivity.KEY_SONG; and
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then downloadSong song.
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Finally, over in MainActivity Inside
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our download buttons
OnClickListener lets start our
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DownloadIntentService instead
of our download service.
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Perfect!
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Now let's test the app and make sure
it still works just like it did before.
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And if we tap the download button,
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and change our log level to debug,
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we can see our song start downloading.
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Then in the Android Device Monitor,
we can kill the process.
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And we can see that our service is
scheduled to be restarted in 52 seconds.
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At least for me.
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And once it's restarted our
songs will continue downloading.
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Using an intense service like
this is exactly the same
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as what we were doing before.
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In fact you can delete download service,
download thread and
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download handler because
we're not using them anymore.
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But you might want to keep them around
as a reference to look back to later.
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We've learned so
much about services in such a short time.
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I know this stuff can seem difficult but
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the more time you spend with it,
the easier it gets.
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Remember, if you have any questions,
don't hesitate to ask in the community.
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