如何使用拦截器在Retrofit 2.0中添加Headers？

Question

我们的团队决定采用Retrofit 2.0,我正在做一些初步的研究.我是这个图书馆的新手.

我想知道如何使用我们的Android应用程序中的Retrofits 2.0interceptor添加自定义标头.有许多关于在Retrofit 1.X中使用添加标题的教程,但由于API在最新版本中发生了很大变化,我不确定如何在新版本中调整这些方法.此外,Retrofit尚未更新其新文档.interceptor

例如,在以下代码中,我应该如何实现Interceptor该类以添加额外的标头？此外,未记载的Chain对象究竟是什么？什么时候会intercept()被召唤？

    OkHttpClient client = new OkHttpClient();
    client.interceptors().add(new Interceptor() {
        @Override
        public Response intercept(Chain chain) throws IOException {
            Response response = chain.proceed(chain.request());

            // How to add extra headers?

            return response;
        }
    });

    Retrofit retrofit = new Retrofit.Builder()
            .baseUrl(BASE_API_URL)
            .client(client)
            .addConverterFactory(GsonConverterFactory.create())
            .build();

Answer 1

看一下这个.

public class HeaderInterceptor
        implements Interceptor {
    @Override
    public Response intercept(Chain chain)
            throws IOException {
        Request request = chain.request();
        request = request.newBuilder()
                .addHeader("appid", "hello")
                .addHeader("deviceplatform", "android")
                .removeHeader("User-Agent")
                .addHeader("User-Agent", "Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:38.0) Gecko/20100101 Firefox/38.0")
                .build();
        Response response = chain.proceed(request);
        return response;
    }
}

科特林

class HeaderInterceptor : Interceptor {
    override fun intercept(chain: Interceptor.Chain): Response = chain.run {
        proceed(
            request()
                .newBuilder()
                .addHeader("appid", "hello")
                .addHeader("deviceplatform", "android")
                .removeHeader("User-Agent")
                .addHeader("User-Agent", "Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:38.0) Gecko/20100101 Firefox/38.0")
                .build()
        )        
    }
}

Answer 2

接受答案的另一种选择

public class HeaderInterceptor implements Interceptor {

    @Override
    public Response intercept(Chain chain) throws IOException {
        Request request = chain.request();

        request = request.newBuilder()
                .addHeader("headerKey0", "HeaderVal0")
                .addHeader("headerKey0", "HeaderVal0--NotReplaced/NorUpdated") //new header added
                .build();

        //alternative
        Headers moreHeaders = request.headers().newBuilder()
                .add("headerKey1", "HeaderVal1")
                .add("headerKey2", "HeaderVal2")
                .set("headerKey2", "HeaderVal2--UpdatedHere") // existing header UPDATED if available, else added.
                .add("headerKey3", "HeaderKey3")
                .add("headerLine4 : headerLine4Val") //line with `:`, spaces doesn't matter.
                .removeAll("headerKey3") //Oops, remove this.
                .build();

        request = request.newBuilder().headers(moreHeaders).build();

        /* ##### List of headers ##### */
        // headerKey0: HeaderVal0
        // headerKey0: HeaderVal0--NotReplaced/NorUpdated
        // headerKey1: HeaderVal1
        // headerKey2: HeaderVal2--UpdatedHere
        // headerLine4: headerLine4Val

        Response response = chain.proceed(request);
        return response;
    }
}