Retrofit2使用CookieJar存储cookie信息，首先创建CookieJar对象

public static final Map<String, List<Cookie>> cookieStore = new HashMap<>();
public static final CookieJar cookieJar = new CookieJar() {
    @Override
    public void saveFromResponse(HttpUrl url, List<Cookie> cookies) {
        cookieStore.put(url.host(), cookies);
    }

    @Override
    public List<Cookie> loadForRequest(HttpUrl url) {
        List<Cookie> cookies = cookieStore.get(url.host());
        return cookies != null ? cookies : new ArrayList<Cookie>();
    }
};

然后需要把cookieJar配置到OkHttpClient中

OkHttpClient okHttpClient = new OkHttpClient.Builder()
                    .cookieJar(cookieJar).build();

最后把okHttpClient配置到Retrofit中

Gson gson = new GsonBuilder().setLenient().create();
Retrofit retrofit = new Retrofit.Builder()
                    .baseUrl(Config.BASE_URL)
                    .client(okHttpClient)
                    .addConverterFactory(GsonConverterFactory.create(gson))
                    .build();