Apresentado no 1o Encontro do Grupo de estudos Android do GDG ABC em 4/Jul/2015

1. Android Libs:
Retrofit

2. ● 20 minutos! (run, Forest, RUN!)
● Objetivo: mostrar uma lib útil e simples p/ desenv Android
● Problema → Retrofit → Vantagens → Ex → The End
Agenda

3. ● Desenvolvedor de Software há 8 anos
● formado no
●
●
Daniel Gimenes

4. O Problema

5. O Problema

6. O Problema
Padrão REST(like)

7. URL url;
HttpURLConnection urlConnection =null;
try {
url = new URL("http://api.mybooks.com/");
urlConnection = (HttpURLConnection) url.openConnection();
InputStream in = urlConnection.getInputStream();
InputStreamReader isw = new InputStreamReader(in);
int data = isw.read();
while (data != -1) {
char current = (char) data;
data = isw.read();
System.out.print(current);
}
} catch (Exception e) {
e.printStackTrace();
} finally {
try {
urlConnection.disconnect();
} catch (Exception e) {
e.printStackTrace();
}
}
O Problema
HTTP Request
- Código grande
- Muito técnico
- Muito longe do
problema da aplicação ISSO SEM
TRATAR OS
ERROS!

8. O Problema
JSON
- String?
- Listas, Dicionários
Eu queria objetos do
meu domínio!
{
"updated_at": "Sat, 04 Jul 2015 01:09:12 +0000",
"books": [
{
"title": "Foundation",
"author": "Isaac Asimov",
"publisher": "Spectra Books",
"isbn10": "0553293354",
"user_rating": 4,
"read_status": "read",
"read_date": "01/01/2001"
},
{
"title": "Snow Crash",
"author": "Neal Stephenson",
"publisher": "Spectra",
"ISBN-10": "0553380958",
"user_rating": 5,
"read_status": "read",
"read_date": "14/05/2011"
},
[...]
]
}

9. Retrofit!!!!

10. ● A type-safe REST* client for Android and Java
○ menos código, mais focado no seu modelo de domínio
● Criada pela Square, Inc.
● Open-Source e gratuita
● http://square.github.io/retrofit/
Retrofit - uma mão na roda!

11. Endpoints e Parâmetros

12. Retrofit - mapeando endpoints
public interface GitHubService {
@GET("/users/{user}/repos")
List<Repo> listRepos(@Path("user") String user);
}
ex.: https://api.github.com/users/123123/repos

13. Retrofit - configurando parâmetros
public interface userBooksService {
@GET("/users/{user_id}/favorite-books")
FavoriteBooks listFavBooks(
@Path("user_id") String userId,
@Query("language") String languageFilter);
}
ex.: https://api.mybooks.com/users/123/favorite-books?language=english

14. Retrofit - configurando parâmetros
@GET
@PUT
@POST
...
@Query
@Path
@Body
@Field
@QueryMap
...
@Headers
@Header
@Multipart
@FormUrlEncoded
...

15. Retrofit - resultado das chamadas
{
"updated": "Sat, 04 Jul 2015 01:09:12",
"books": [
{
"title": "Foundation",
"author": "Isaac Asimov",
"publisher": "Spectra Books",
"isbn10": "0553293354",
"user_rating": 4,
"read_status": "read",
"read_date": "01/01/2001"
},
{
"title": "Snow Crash",
"author": "Neal Stephenson",
"publisher": "Spectra",
"isbn10": "0553380958",
[...]
},
[...]
public class FavoriteBooks {
private String updated;
private List<Book> books;
[...]
}
public class Book {
private String title;
private String author;
private String publisher;
private String isbn10;
private Integer user_rating;
private String status;
[...]
}

16. Retrofit - resultado das chamadas
● Síncrono
public interface GitHubService {
@GET("/users/{user}/repos")
List<Repo> listRepos(@Path("user") String user);
}
ex.: https://api.github.com/users/123123/repos

17. Retrofit - resultado das chamadas
● Assíncrono
public interface GitHubService {
@GET("/users/{user}/repos")
void listRepos(
@Path("user") String user,
Callback<Repo> callback);
}
ex.: https://api.github.com/users/123123/repos

18. Retrofit - objeto “webservice”
RestAdapter restAdapter = new RestAdapter.Builder()
.setEndpoint("https://api.github.com" )
.build();
GitHubService service = restAdapter.create(GitHubService. class);

19. Configuração

20. Retrofit - configuração
compile 'com.squareup.retrofit:retrofit:1.9.0'
● build.gradle:

21. Vantagens e outras features

22. ● comunicação com webservices HTTP+JSON facilitada
● parsing JSON <-> POJO automática
● simplicidade de código
○ + fácil de entender e manter
○ - chance de bugs
● pode ser extendido facilmente
● e mais…
Retrofit - vantagens!

23. ● Outras features:
○ logging automático de todas as requests
○ manipulação de headers (cache, autorização, etc)
○ conversores personalizados com GsonConverter
○ tratamento de erros facilitado
○ integração com RxJava.
Retrofit - vantagens!

24. Exemplo!

25. Retrofit - exemplo rapidinho!

26. Retrofit - exemplo rapidinho!

27. Retrofit - exemplo rapidinho!
{
"url": "http://apod.nasa.gov/apod/image/1507/Jowisz_i_Wenus2Tomaszewski1024.jpg",
"media_type": "image",
"explanation": "On June 30 Venus and Jupiter were actually far apart, but both appeared
close in western skies at dusk. Near the culmination of this year's gorgeous conjunction,
the two bright evening planets are captured in the same telescopic field of view in this
sharp digital stack of images taken after sunset from Pozna&nacute; in west-central Poland.
In fact, banded gas giant [...]",
"concepts": null,
"title": "Venus and Jupiter are Far"
}
ex.: https://api.nasa.gov/planetary/apod?concept_tags=false&api_key=DEMO_KEY

28. Retrofit - exemplo rapidinho!
public interface NasaWebservice {
@GET("/apod")
void getAPOD(@Query("api_key") String nasaApiKey ,
@Query("concept_tags" ) boolean conceptTags,
Callback<ApodDTO> callback) ;
}

29. Retrofit - exemplo rapidinho!
public class ApodDTO {
private String url;
private String mediaType;
private String explanation;
private List<String> concepts;
private String title;
[...]
}

30. Retrofit - exemplo rapidinho!
public class ApodInteractor {
private static final String NASA_API_KEY = "DEMO_KEY";
private static final String NASA_API_BASE_URL = "https://api.nasa.gov/planetary";
private final NasaWebservice nasaWebservice;
public ApodInteractor() {
RestAdapter restAdapter = new RestAdapter.Builder()
.setLogLevel(RestAdapter.LogLevel.FULL)
.setEndpoint(NASA_API_BASE_URL)
.build();
this.nasaWebservice = restAdapter.create(NasaWebservice.class);
}

31. Retrofit - exemplo rapidinho!
public class ApodInteractor {
[...]
public void getNasaApodURI(final OnFinishListener<String> onFinishListener) {
nasaWebservice.getAPOD(NASA_API_KEY, false, new Callback<ApodDTO>() {
@Override
public void success(ApodDTO apodDTO, Response response) {
onFinishListener.onSuccess(apodDTO.getUrl());
}
@Override
public void failure(RetrofitError error) {
onFinishListener.onError(error.getCause());
}
});
}
}

32. Retrofit - exemplo rapidinho!
github.com/danielgimenes/NasaPic

33. Obrigado!
Daniel Costa Gimenes
br.linkedin.com/in/danielcgimenes/
danielcgimenes@gmail.com
github.com/danielgimenes/