Okhttp動態創建責任鏈式Interceptor

攔截器容器，裝載了所有攔截器

 private List<Interceptor> interceptors = new ArrayList<>();

 攔截器容器添加攔截器

public void addInterceptors(Interceptor interceptor) {
        this.interceptors.add(interceptor);
}

創建OKhttp配置一個默認攔截器

OkHttpClient.Builder mOkHttpBuilder = new OkHttpClient.Builder()
        .addNetworkInterceptor(new HttpLoggingInterceptor().setLevel(HttpLoggingInterceptor.Level.BODY))
        .addInterceptor(默認攔截器)
        .connectTimeout(DEFAULT_TIMEOUT, TimeUnit.SECONDS);

 默認攔截器實現：創建攔截器責任鏈表

    @Override
    public Response intercept(Chain chain) throws IOException {
        return new TChain(interceptors, chain).proceed();
    }

 自定義責任鏈表類

 class TChain implements Chain {
        private List<Interceptor> interceptors;
        private Chain chain;
        private Request request;
        private int index = 0;

        public TChain(List<Interceptor> interceptors, Chain chain) {
            this(interceptors, chain, chain.request(), 0);
        }
        private TChain(List<Interceptor> interceptors, Chain chain, Request request, int index) {
            this.interceptors = interceptors;
            this.chain = chain;
            this.request = request;
            this.index = index;
        }
        /**
         * 依次取出攔截器鏈表中的每個攔截器去獲取Response
         *
         * @param request
         * @return
         * @throws IOException
         */
        @Override
        public Response proceed(Request request) throws IOException {
            return index >= interceptors.size() ? chain.proceed(request) : interceptors.get(index).intercept(new TChain(interceptors, chain, this.request = request, index + 1));
        }
        @Override
        public Request request() {
            return request;
        }
        public Response proceed() throws IOException {
            return proceed(this.request);
        }
        @Override
        public Connection connection() {
            return chain.connection();
        }
        @Override
        public Call call() {
            return chain.call();
        }
        @Override
        public int connectTimeoutMillis() {
            return chain.connectTimeoutMillis();
        }
        @Override
        public Chain withConnectTimeout(int timeout, TimeUnit unit) {
            return chain.withConnectTimeout(timeout, unit);
        }
        @Override
        public int readTimeoutMillis() {
            return chain.readTimeoutMillis();
        }
        @Override
        public Chain withReadTimeout(int timeout, TimeUnit unit) {
            return chain.withConnectTimeout(timeout, unit);
        }
        @Override
        public int writeTimeoutMillis() {
            return chain.writeTimeoutMillis();
        }
        @Override
        public Chain withWriteTimeout(int timeout, TimeUnit unit) {
            return chain.withWriteTimeout(timeout, unit);
        }
    }