Retrofit

* Released by Square.

* Retrofit turns your REST API into a Java interface.

* Offers very easy to use REST API Solution.

Retrofit Performance Analysis

Retrofit uses these library

lOkHttp

lGSON

lRxJava

GSONlConversion of an object to json or from json to object.

lAll the fields by default are included in conversions even private fields

lIf don’t want to include the field in conversion, use transient modifier for that field

GSON Implementation

* This is a class for Person-public class Person { public String id;@SerializedName(user_name) public String name; public Person parent;//setter getter here}Obtains result like this{"id":1,"name":"testName","parent":2}

GSON Implementation

GSON Serializationclass PersonSerializer implements JsonSerializer<Person> { public JsonElement serialize(final Person person, Type type,JsonSerializationContext context) { JsonObject result = new JsonObject(); result.add("id", new JsonPrimitive(person.getId())); result.add("name", new JsonPrimitive(person.getName())); Person parent = person.getParent(); if (parent != null) {result.add("parent", new JsonPrimitive(parent.getId())); } return result; } }

RxJava

Reactive Programming

Reactive Programming

Reactive Programming

Retrofit

1-Create Interface for API and declare methods for each REST Call

2-Specify method type Using Annotations-@GET,@POST,@PUT

3-For paramenters use -@Path,@Query,@Body

4-Use RestAdapter to build the service client.

Retrofit Interface

public interface TestService { @GET("/users/{user}/person") List<Person> listPerson(@Path("user") String user);}RestAdapter restAdapter = new RestAdapter.Builder() .setEndpoint("https://api.test.com") .build();TestService service = restAdapter.create(TestService.class);List<Person> temp = service.listPerson("xyz");

Interface's MethodslA method with a return type will be executed synchronously.

lAsynchronous execution requires the last parameter of the method be a Callback.

l Using RxJava we can have return type as Observable

Interface's MethodslPublic interface TestInterface{@GET("/users/list")Photo userList(); //Synchronous call

@POST("/users/list")void userList(@Body User ,Callback<TResponse> cb);//Asynchronous call

@GET("/users/list")Observable<TResponse> userList();//Observablel}

HEADER MANIPULATIONlSet static headers for a method usingl@Headers("Cache-Control: max-age=640000")

lUse when need to send same header for all api-lRequestInterceptor requestInterceptor = new RequestInterceptor() {l @Overridel public void intercept(RequestFacade request) {l request.addHeader("User-Agent", "Retrofit-Sample-App");l }l};

Retrofit Implementation

* Retrofit uses Gson by default to convert HTTP bodies to and from JSON.

* Custom GSON Converter ExampleIf you want to specify behavior that is different from Gson's defaults.

GsonBuilder gson = new GsonBuilder();gson.registerTypeAdapter(MyType2.class, new MyTypeAdapter());

Retrofit Implementation* Create gson object this way- Gson gson = new GsonBuilder().registerTypeAdapter(Person.class, new PersonSerializer()) .create();* Pass this object to .setConverter

RestAdapter restAdapter = new RestAdapter.Builder() .setEndpoint("https://api.github.com") .setConverter(new GsonConverter(gson)) .build();

RestAdapter*Using RestAdapter Object we initialize Interface reference or service client.* It has static class RestAdapter.Builder. methods inside RestAdapter.Builder class- *setEndpoint-API endpoint URL *setClient-The HTTP client used for requests *setRequestInterceptor-for adding Header/data to every request. setConverter-converter used for serialization and deserialization of objects.

Retrofit Implementation

* RestAdapter.Builder() .setEndpoint(“http://www.githubservice.com”).setClient(new OkClient(okHttpClientWithCache())).setConverter(new GsonConverter(new GsonBuilder().registerTypeAdapter(Test.class, new TestDeserializer()) .build() .create(TestInterface.class);

Retrofit Implementation* Use http://www.jsonschema2pojo.org/ to create POJO classes. Lets take this example-{ "weather":[ { "id":711, "main":"Smoke", "description":"smoke", "icon":"50n" }]}

Retrofit Implementation

Implementaion

* It Shows how to use SimpleXMLConverter to communicate with an API that uses XML

RestAdapter restAdapter = new RestAdapter.Builder() .setEndpoint("https://api.soundcloud.com") .setConverter(new SimpleXMLConverter()) .build();

TestInterrface service = restAdapter.create(TestInterface.class);

THANK YOU

l

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