方式一、直接在参数里写 每次访问的时候都要传入一下
@GET("weatherservice/citylist")
Observable<WeatherRestBean> request(@Header("apikey") String apikey,@Query("cityname") String cityname);
方式二、写到注解里这样就少了个参数，但是每定义个接口都要写一次也是比较麻烦
@Headers("apikey:ac7c302dc489a69082cbee6a89e3646c")
@GET("weatherservice/cityid") request<WeatherEntity> query(@Query("cityid")String cityid);
方式三、在创建Retrofit的时候添加，最方便的方式
OkHttpClient client = new OkHttpClient.Builder()
.addInterceptor(new Interceptor() {
@Override
public Response intercept(Chain chain) throws IOException {
Request request = chain.request();
Request.Builder builder1 = request.newBuilder();
Request build = builder1.addHeader("apikey", "ac7c302dc489a69082cbee6********").build();
return chain.proceed(build); } })
.retryOnConnectionFailure(true)
.build();
mRetrofit = new Retrofit.Builder()
.client(client)
.baseUrl(ConstantApi.url)
.addCallAdapterFactory(...
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