okhttp源碼學習（五）BridgeInterceptor

核心功能

1.請求從應用層數據類型類型轉化爲網絡調用層的數據類型
2.將網絡層返回的數據類型 轉化爲 應用層數據類型。
源碼

  public Response intercept(Chain chain) throws IOException {
    //處理請求部分
    Request userRequest = chain.request();
    Request.Builder requestBuilder = userRequest.newBuilder();

    RequestBody body = userRequest.body();
    if (body != null) {
      MediaType contentType = body.contentType();
      if (contentType != null) {
        requestBuilder.header("Content-Type", contentType.toString());
      }

      long contentLength = body.contentLength();
      if (contentLength != -1) {
        requestBuilder.header("Content-Length", Long.toString(contentLength));
        requestBuilder.removeHeader("Transfer-Encoding");
      } else {
        requestBuilder.header("Transfer-Encoding", "chunked");
        requestBuilder.removeHeader("Content-Length");
      }
    }

    if (userRequest.header("Host") == null) {
      requestBuilder.header("Host", hostHeader(userRequest.url(), false));
    }

    if (userRequest.header("Connection") == null) {
      requestBuilder.header("Connection", "Keep-Alive");
    }

    // If we add an "Accept-Encoding: gzip" header field we're responsible for also decompressing
    // the transfer stream.
    boolean transparentGzip = false;
    if (userRequest.header("Accept-Encoding") == null && userRequest.header("Range") == null) {
      transparentGzip = true;
      requestBuilder.header("Accept-Encoding", "gzip");
    }
    // 所以返回的cookies不能爲空，否則這裏會報空指針
    List<Cookie> cookies = cookieJar.loadForRequest(userRequest.url());

    if (!cookies.isEmpty()) {
      requestBuilder.header("Cookie", cookieHeader(cookies));
    }

    if (userRequest.header("User-Agent") == null) {

    }
//處理響應部分
    Response networkResponse = chain.proceed(requestBuilder.build());

    // 響應header， 如果沒有自定義配置cookie不會解析
    HttpHeaders.receiveHeaders(cookieJar, userRequest.url(), networkResponse.headers());

    Response.Builder responseBuilder = networkResponse.newBuilder()
        .request(userRequest);
    // 前面解析完header後，判斷服務器是否支持gzip壓縮格式，如果支持將交給Okio處理
    if (transparentGzip
        && "gzip".equalsIgnoreCase(networkResponse.header("Content-Encoding"))
        && HttpHeaders.hasBody(networkResponse)) {
      GzipSource responseBody = new GzipSource(networkResponse.body().source());
      Headers strippedHeaders = networkResponse.headers().newBuilder()
          .removeAll("Content-Encoding")
          .removeAll("Content-Length")
          .build();
      responseBuilder.headers(strippedHeaders);
      String contentType = networkResponse.header("Content-Type");
      // 處理完成後，重新生成一個response
      responseBuilder.body(new RealResponseBody(contentType, -1L, Okio.buffer(responseBody)));
    }

    return responseBuilder.build();
  }

在源碼中我們也可以看出來也是主要分成兩個部分
請求部分：
1.補全全header信息 Content-Type、Content-Length、Transfer-Encoding、Host、Connection、Accept-Encoding、User-Agent 等
2..如果需要gzip壓縮則進行gzip壓縮
3.加載Cookie
4.進入下一個interceptor並傳遞request
響應部分
1.如果服務器的響應的content是經過gzip壓縮的則移除響應中header
的Content-Encoding和Content-Length，構造新的響應返回。
2.返回response

最後獻上一份添加了註釋的源碼 https://github.com/525642022/okhttpTest/blob/master/README.md
哈哈