Retrofit

 

Retrofit은 서버와 클라이언트 간 http 통신을 위한 라이브러리이다.

즉, Android에서 http 통신을 할 수 있도록 해주는 친구이다.

 

AndroidManifest.xml

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

 

build.gradle

implementation 'com.squareup.retrofit2:retrofit:2.9.0'
implementation 'com.squareup.retrofit2:converter-gson:2.9.0'

 

 

 

 

MainActivity.kt (JSONPlaceholder사이트에서 API호출 및 테스팅 했음.)

https://jsonplaceholder.typicode.com/

 

// Simple Retrofit Ex
// https://jsonplaceholder.typicode.com/
// https://jsonplaceholder.typicode.com/posts
// https://jsonplaceholder.typicode.com/posts/2

class MainActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        val api = RetrofitInstance.getInstance().create(MyApi::class.java)
        api.getPost1().enqueue(object : Callback<Post> {
            override fun onResponse(call: Call<Post>, response: Response<Post>) {
                Log.d("API1", response.body().toString())
            }

            override fun onFailure(call: Call<Post>, t: Throwable) {
                Log.d("API1", "fail")
            }

        })

        api.getPostNumber(2).enqueue(object : Callback<Post> {
            override fun onResponse(call: Call<Post>, response: Response<Post>) {
                Log.d("API2", response.body().toString())
            }

            override fun onFailure(call: Call<Post>, t: Throwable) {
                Log.d("API2", "fail")
            }

        })

    }
}

 

RetrofitInstance.kt

object RetrofitInstance {

    val BASE_URL = "https://jsonplaceholder.typicode.com/"

    val client = Retrofit
        .Builder()
        .baseUrl(BASE_URL)
        .addConverterFactory(GsonConverterFactory.create())
        .build()

    fun getInstance() : Retrofit {
        return client
    }

}

 

 

Post.kt

data class Post (
    val userId : Int,
    val id : Int,
    val title : String,
    val body : String
)

 

 

MyApi.kt

interface MyApi {

    @GET("posts/1")
    fun getPost1() : Call<Post>

    @GET("posts/{number}")
    fun getPostNumber(
        @Path("number") number : Int
    ) : Call<Post>

}

 

결과:API로 받아온 정보 두개가 로그에 찍혔다.