http://square.github.io/retrofit/

Retrofit2 + OkHttp3 + Jackson + RxAndroid2/RxJava2

https://mvnrepository.com/artifact/com.squareup.okhttp3/okhttp https://mvnrepository.com/artifact/com.squareup.okhttp3/okhttp-urlconnection

compile 'com.squareup.okhttp3:okhttp:3.8.0'
compile 'com.squareup.okhttp3:okhttp-urlconnection:3.8.0'
compile 'com.squareup.okhttp3:logging-interceptor:3.8.0'

compile 'com.squareup.retrofit2:retrofit:2.3.0'
compile 'com.squareup.retrofit2:converter-jackson:2.3.0'
compile 'com.squareup.retrofit2:adapter-rxjava2:2.3.0'

compile 'com.fasterxml.jackson.core:jackson-core:2.8.8'
compile 'com.fasterxml.jackson.core:jackson-databind:2.8.8.1'
compile 'com.fasterxml.jackson.core:jackson-annotations:2.8.8'

//Android
compile 'io.reactivex.rxjava2:rxandroid:2.0.1'
//Java
compile 'io.reactivex.rxjava2:rxjava:2.1.0'

public class RestfulAdapter {

    public static final int CONNECT_TIMEOUT = 15;
    public static final int WRITE_TIMEOUT = 15;
    public static final int READ_TIMEOUT = 15;

    private static volatile ConcurrentHashMap<String, Object> services = new ConcurrentHashMap<>();

    public static synchronized <T> T getInstance(Class<T> restfulInterface) throws Exception {
        if(!restfulInterface.isInterface())
            throw new IllegalArgumentException("argument must be INTERFACE");

        T service = (T) services.get(restfulInterface.getName());

        if(service == null) {
            Field f = restfulInterface.getField("URL");
            String url = (String) f.get(null);

            HttpLoggingInterceptor httpLoggingInterceptor = new HttpLoggingInterceptor();
            httpLoggingInterceptor.setLevel(HttpLoggingInterceptor.Level.BODY);

            CookieManager cookieManager = new CookieManager();
            cookieManager.setCookiePolicy(CookiePolicy.ACCEPT_ALL);

            OkHttpClient client = configureClient() // 인증서 무시
                    .connectTimeout(CONNECT_TIMEOUT, TimeUnit.SECONDS)
                    .writeTimeout(WRITE_TIMEOUT, TimeUnit.SECONDS)
                    .readTimeout(READ_TIMEOUT, TimeUnit.SECONDS)
                    .cookieJar(new JavaNetCookieJar(cookieManager)) //쿠키 설정
                    .addInterceptor(httpLoggingInterceptor) //http 로그 확인
                    .build();

            service = new Retrofit.Builder()
                    .baseUrl(url)
                    .client(client)
                    .addCallAdapterFactory(RxJava2CallAdapterFactory.create())
                    .addConverterFactory(JacksonConverterFactory.create())
                    .build().create(restfulInterface);

            services.put(restfulInterface.getName(), service);
        }

        return service;
    }

    /**
     * 인증서 무시
     * @return
     */
    private static OkHttpClient.Builder configureClient() throws Exception {
        TrustManagerFactory trustManagerFactory = TrustManagerFactory.getInstance(TrustManagerFactory.getDefaultAlgorithm());
        trustManagerFactory.init((KeyStore) null);
        TrustManager[] trustManagers = trustManagerFactory.getTrustManagers();

        if (trustManagers.length != 1 || !(trustManagers[0] instanceof X509TrustManager))
            throw new IllegalStateException("Unexpected default trust managers:" + Arrays.toString(trustManagers));

        X509TrustManager trustManager = (X509TrustManager) trustManagers[0];

        SSLContext sslContext = SSLContext.getInstance("SSL");
        sslContext.init(null, new TrustManager[] { trustManager }, new SecureRandom());

        OkHttpClient.Builder builder = new OkHttpClient.Builder();
        builder.sslSocketFactory(sslContext.getSocketFactory(), trustManager).hostnameVerifier((hostname, session) -> true);

        return builder;
    }
}