Développer une app Android en 2015

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Mais avant Petit retour en arrière…

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Requêtes HTTP Parsing Gestion des données Exécution en background Gestion des crashs Design

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Florian Mierzejewski @florianmski

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Données Obtenir, Manipuler, Stocker

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Retroﬁt, OkHttp A ■ Production

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OkHttp An HTTP & SPDY client for Android and Java applications • Support de HTTP/2 et SPDY • Support de GZIP • Réponses en cache

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Retroﬁt A type-safe REST client for Android and Java Utilisation d’annotations pour décrire les requêtes HTTP

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List comments( String movieId, Integer page, Integer limit ); /movies/{id}/comments?page={page}&limit={limit}

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@GET("/movies/{id}/comments") List comments( String movieId, Integer page, Integer limit );

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@GET("/movies/{id}/comments") List comments( @Path("id") String movieId, Integer page, Integer limit ); /movies/{id}/comments

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@GET("/movies/{id}/comments") List comments( @Path("id") String movieId, @Query("page") Integer page, @Query("limit") Integer limit ); /movies/{id}/comments?page={page}&limit={limit}

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public interface Movies { ! @GET("/movies/{id}/comments") List comments(/*…*/); ! @GET("/movies/popular") List popular(/*…*/); }

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RestAdapter restAdapter = new RestAdapter.Builder() .setEndpoint(“https://api-v2launch.trakt.tv”) .build();

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RestAdapter restAdapter = new RestAdapter.Builder() .setEndpoint(“https://api-v2launch.trakt.tv”) .build(); ! Movies movies = restAdapter.create(Movies.class);

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RestAdapter restAdapter = new RestAdapter.Builder() .setEndpoint(“https://api-v2launch.trakt.tv”) .build(); ! Movies movies = restAdapter.create(Movies.class); ! List comments = movies.comments(42, 1, 10);

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RestAdapter restAdapter = new RestAdapter.Builder() .setEndpoint(“https://api-v2launch.trakt.tv”) .setConverter(new SimpleXMLConverter()) .build();

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RestAdapter restAdapter = new RestAdapter.Builder() .setEndpoint(“https://api-v2launch.trakt.tv”) .setClient(new OkClient()) .build();

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RestAdapter restAdapter = new RestAdapter.Builder() .setEndpoint(“https://api-v2launch.trakt.tv”) .setLogLevel(RestAdapter.LogLevel.FULL) .build();

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RestAdapter restAdapter = new RestAdapter.Builder() .setEndpoint(“https://api-v2launch.trakt.tv”) .setErrorHandler(new MyErrorHandler()) .build();

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RestAdapter restAdapter = new RestAdapter.Builder() .setEndpoint(“https://api-v2launch.trakt.tv”) .setRequestInterceptor(new RequestInterceptor() { @Override public void intercept(RequestFacade request) { request.addHeader(“trakt-api-key”, apiKey); } }) .build();

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@GET("/movies/{id}/comments") List comments(/*…*/); ! @GET("/movies/{id}/comments") void comments(/*…*/, Callback> cb); ! @GET("/movies/{id}/comments") Response comments(/*…*/); ! @GET("/movies/{id}/comments") Observable> comments(/*…*/);

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RxJava A Netflix Original

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Implémentation des Reactive Extensions pour la JVM

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• Pas de dépendance • Jar < 700KB • Java 6+ & Android 2.3+ • Support des lambdas de Java 8 • Polyglotte (Scala, Groovy, Clojure et Kotlin) • Exécution synchrone ou asynchrone

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Composer des programmes asynchrones et basés sur des évènements en utilisant des séquences observables

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Observable Observer

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public interface Observer { ! public abstract void onNext(T t); ! public abstract void onCompleted(); ! public abstract void onError(Throwable e); ! }

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public interface Observer { ! public abstract void onNext(T t); ! public abstract void onCompleted(); ! public abstract void onError(Throwable e); ! }

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public interface Observer { ! public abstract void onNext(T t); ! public abstract void onCompleted(); ! public abstract void onError(Throwable e); ! }

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Créer un Observable

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Observable Observable.just(T value)

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Observable Observable.from(T… values)

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Observable Observable.create(new Observable.OnSubscribe() { @Override public void call(Subscriber super Integer> observer) { try { if (!observer.isUnsubscribed()) { for (int i = 1; i < 5; i++) { observer.onNext(i); } observer.onCompleted(); } } catch (Exception e) { observer.onError(e); } } } );

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S’abonner

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Observable getObservable().subscribe(myObserver)

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Composer

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Transformer Observable map(Func1 func)

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Combiner merge(Observable t1, Observable t2)

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Filtrer Observable distinct()

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Gestion des erreurs onErrorResumeNext(Observable o)

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Et concrètement ?

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compile 'io.reactivex:rxandroid:0.23.0'

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Observable.just(1, 2, 3) .subscribe(new Subscriber() { @Override public void onNext(Integer item) { System.out.println("Next: " + item); } ! @Override public void onError(Throwable error) { System.err.println("Error: " + error.getMessage()); } ! @Override public void onCompleted() { System.out.println("Sequence complete."); } });

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> Next: 1 > Next: 2 > Next: 3 > Sequence complete.

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Hum, un vrai exemple ?

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comments(42, 1, 10) .ﬁlter(c -> !c.spoiler) .toSortedList((c1, c2) -> Integer.compare(c2.likes, c1.likes)) .lift(flattenList()) .take(3) .subscribeOn(Schedulers.io()) .observeOn(AndroidSchedulers.mainThread()) .subscribe(myObserver);

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createObservable() .subscribeOn(Schedulers.io()) .observeOn(AndroidSchedulers.mainThread()) .subscribe(myObserver);

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createObservable() .subscribeOn(Schedulers.io()) .observeOn(AndroidSchedulers.mainThread()) .subscribe(myObserver);

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createObservable() .subscribeOn(Schedulers.io()) .observeOn(AndroidSchedulers.mainThread()) .subscribe(myObserver);

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@Override public void onDestroy() { super.onDestroy(); ! subscription.unsubscribe(); }

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Mais aussi Les subjects Observables “hot” ou “cold” …

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ContentProvider Like a boss

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Pourquoi un ContentProvider ? ! • Système de notiﬁcation des URIs • Reste assez “bas niveau” pour faire ce que l’on veut

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Ce qui est moins cool ! • Beaucoup de boilerplate • Difﬁcile de ne pas faire d’erreurs

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Schematic à la rescousse ! ! • Génération du ContentProvider • Annotations, annotations everywhere • Permet de se concentrer sur le schéma et la bonne gestion des URIs https://github.com/SimonVT/schematic

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Par contre ! • Très peu de documentation • “La documentation c’est le code” • SimonVT/cathode - ProviderSchematic.java https://github.com/SimonVT/schematic

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public interface MovieColumns { @DataType(INTEGER) @PrimaryKey @AutoIncrement String ID = “_id”; /* … */ } ! Supporte également @DefaultValue, @NotNull, @References et @Unique https://github.com/SimonVT/schematic

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DatabaseX.java ! @Table(MovieColumns.class) public static ﬁnal String MOVIES = “movies"; /* … */ ! @ExecOnCreate // indexes, triggers… https://github.com/SimonVT/schematic

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ProviderX.java ! @TableEndpoint(table = DatabaseSchematic.MOVIES) public static class Movies { ! } https://github.com/SimonVT/schematic

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ProviderX.java - Movies ! @ContentUri( path = Path.MOVIES, type = "vnd.android.cursor.dir/movie") public static ﬁnal Uri CONTENT_URI = buildUri(Path.MOVIES); https://github.com/SimonVT/schematic

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ProviderX.java - Movies ! @InexactContentUri( path = Path.MOVIES + "/#", name = "MOVIE_ID", type = "vnd.android.cursor.item/movie", whereColumn = MovieColumns.ID_TRAKT, pathSegment = 1) public static Uri withId(String traktId) { return buildUri(Path.MOVIES, traktId); } https://github.com/SimonVT/schematic

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https://github.com/SimonVT/schematic content://.../movies content://.../movies/42 content://.../movies/1337

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ProviderX.java - Movies ! ! @NotifyUpdate(paths = Path.MOVIES + "/#") public static Uri[] notifyUpdate(Context context, Uri uri, String where, String[] whereArgs) { int id = Integer.valueOf(uri.getPathSegments().get(1)); return new Uri[]{CONTENT_URI, withId(id)} } https://github.com/SimonVT/schematic

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Du Rx dans votre base https://github.com/square/sqlbrite ! • Wrap SQLiteOpenHelper • Requêtes en base deviennent des Observables • Supporte les notiﬁcations quand une table est modiﬁée

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User Interface Material, Animations, RecyclerView

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Material YHolo!

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Material is the metaphor Bold, graphic, intentional Motion provides meaning

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Material is the metaphor Bold, graphic, intentional Motion provides meaning

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Material is the metaphor Bold, graphic, intentional Motion provides meaning

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Un doute ? https://github.com/google/iosched

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Animations et autres tricks

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Spans, a Powerful Concept. http://flavienlaurent.com/blog/2014/01/31/spans/

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RecyclerView R.I.P {List/Grid/…}View

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RecyclerView =/= ListView

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Gère le recyclage des vues, point Un composant flexible

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Dessus, on plug : LayoutManager ItemDecoration ItemAnimator

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Ce qui est cool : ! • 3 LayoutManager de base • Animations • Modiﬁer l’orientation • Layout depuis le haut ou le bas • Gestion des spans

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Ce qui l’est moins : ! • Dividers ? • Headers / Footers ? • Réécrire les adapters • OnItemClickListener ? • ChoiceModes ?

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Headers / Footers ! 1. Wrapper l’adapter dans un autre 2. Gérer les headers / footers à la main 3. Ecrire son propre LayoutManager 4. Padding et Translation

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recyclerView.setHasFixedSize(true); recyclerView.setLayoutManager(new LinearLayoutManager(getActivity())); recyclerView.setAdapter(new RecyclerUserAdapter());

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recyclerView.setHasFixedSize(true); recyclerView.setLayoutManager(new LinearLayoutManager(getActivity())); recyclerView.setAdapter(new RecyclerUserAdapter());

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recyclerView.setHasFixedSize(true); recyclerView.setLayoutManager(new LinearLayoutManager(getActivity())); recyclerView.setAdapter(new RecyclerUserAdapter());

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Deux “astuces”

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Une ligne de code pour supporter tous les types d’écrans ! new GridLayoutManager( getActivity(), getResources().getInteger(R.integer.grid_poster_columns)); res/values integers.xml 3 res/values-land … res/values-sw600dp … …

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manager.setSpanSizeLookup(new GridLayoutManager.SpanSizeLookup() { @Override public int getSpanSize(int position) { return getAdapter().isHeader(position) ? manager.getSpanCount() : 1; } });