1.先添加依赖
compile 'com.squareup.retrofit2:retrofit:2.3.0'
compile 'com.squareup.retrofit2:converter-gson:2.3.0'
//引入Log拦截器，方便DEBUG模式输出log信息
compile 'com.squareup.okhttp3:logging-interceptor:3.5.0'
compile 'com.github.franmontiel:PersistentCookieJar:v1.0.1'
2.创建一个接口类（比如下图）
3.新建application类
HttpLoggingInterceptor loggingInterceptor = new HttpLoggingInterceptor();
loggingInterceptor.setLevel(HttpLoggingInterceptor.Level.BODY);
Gson gson = new GsonBuilder()
.setDateFormat("yyyy-MM-dd'T'HH:mm:ssZ")
.create();//使用 gson coverter，统一日期请求格式
OkHttpClient okHttpClient = new OkHttpClient.Builder()
.connectTimeout(CONNECT_TIMEOUT, TimeUnit.SECONDS)
.readTimeout(READ_TIMEOUT, TimeUnit.SECONDS)
.writeTimeout(WRITE_TIMEOUT, TimeUnit.SECONDS)
.addInterceptor(loggingInterceptor)
.cookieJar(new PersistentCookieJar(new SetCookieCache(),new SharedPrefsCookiePersistor(this)))
.build();
Retrofit retrofit = new Retrofit.Builder()
.baseUrl(Constant.BASE_URL)
.addConverterFactory(GsonConverterFactory.create(gson))
.client(okHttpClient)
.build();
HttpApi mApi = retrofit.create(HttpApi.class);
（mApi抽取成静态成员变量，方便直接调用）
4.Get请求如图1
Post请求如下图（分带参和无参）
