OkHttp interceptor to obtain the contents of Response.body

OkHttp interceptor to obtain the contents of Response.body

In the project, due to the use of cookies, the agreed validity period is 20 minutes, so there may be situations where the cookie expires, the operation is not authorized, and you need to log in again.
It seems unrealistic to handle unauthorized operation errors everywhere, so I thought of using interceptors.

But after using the interceptor to obtain Response.body.string(), the subsequent operation directly returns Failed, probably because the stream can only be used once.

@Override
public Response intercept(Chain chain) throws IOException {

        Request request = chain.request();
        Response response = chain.proceed(request);
       
   		L.i("response.body.string:" + response.body().string());
       
		return response;	
}

Later, I thought about how the set HttpLoggingInterceptor() interceptor obtained the response body data?

OkHttpClient client = new OkHttpClient.Builder()
                .addInterceptor(new HttpLoggingInterceptor()
                        .setLevel(HttpLoggingInterceptor.Level.BODY))
						.build();  

So I looked at the source code of HttpLoggingInterceptor

public final class HttpLoggingInterceptor implements Interceptor {
  private static final Charset UTF8 = Charset.forName("UTF-8");

  @Override public Response intercept(Chain chain) throws IOException {
    Level level = this.level;

    Request request = chain.request();

	//如果Log Level 级别为NONOE，则不打印，直接返回
    if (level == Level.NONE) {
      return chain.proceed(request);
    }

	//是否打印body
    boolean logBody = level == Level.BODY;
    //是否打印header
	boolean logHeaders = logBody || level == Level.HEADERS;

	//获得请求body
    RequestBody requestBody = request.body();
	//请求body是否为空
    boolean hasRequestBody = requestBody != null;

	//获得Connection，内部有route、socket、handshake、protocol方法
    Connection connection = chain.connection();
	//如果Connection为null，返回HTTP_1_1，否则返回connection.protocol()
    Protocol protocol = connection != null ? connection.protocol() : Protocol.HTTP_1_1;
	//比如: --> POST http://121.40.227.8:8088/api http/1.1
    String requestStartMessage = "--> " + request.method() + ' ' + request.url() + ' ' + protocol;
    if (!logHeaders && hasRequestBody) {
      requestStartMessage += " (" + requestBody.contentLength() + "-byte body)";
    }
    logger.log(requestStartMessage);

	//打印 Request
    if (logHeaders) {
      if (hasRequestBody) {
        // Request body headers are only present when installed as a network interceptor. Force
        // them to be included (when available) so there values are known.
        if (requestBody.contentType() != null) {
          logger.log("Content-Type: " + requestBody.contentType());
        }
        if (requestBody.contentLength() != -1) {
          logger.log("Content-Length: " + requestBody.contentLength());
        }
      }

      Headers headers = request.headers();
      for (int i = 0, count = headers.size(); i < count; i++) {
        String name = headers.name(i);
        // Skip headers from the request body as they are explicitly logged above.
        if (!"Content-Type".equalsIgnoreCase(name) && !"Content-Length".equalsIgnoreCase(name)) {
          logger.log(name + ": " + headers.value(i));
        }
      }

      if (!logBody || !hasRequestBody) {
        logger.log("--> END " + request.method());
      } else if (bodyEncoded(request.headers())) {
        logger.log("--> END " + request.method() + " (encoded body omitted)");
      } else {
        Buffer buffer = new Buffer();
        requestBody.writeTo(buffer);

		//编码设为UTF-8
        Charset charset = UTF8;
        MediaType contentType = requestBody.contentType();
        if (contentType != null) {
          charset = contentType.charset(UTF8);
        }

        logger.log("");
        if (isPlaintext(buffer)) {
          logger.log(buffer.readString(charset));
          logger.log("--> END " + request.method()
              + " (" + requestBody.contentLength() + "-byte body)");
        } else {
          logger.log("--> END " + request.method() + " (binary "
              + requestBody.contentLength() + "-byte body omitted)");
        }
      }
    }

	//打印 Response
    long startNs = System.nanoTime();
    Response response;
    try {
      response = chain.proceed(request);
    } catch (Exception e) {
      logger.log("<-- HTTP FAILED: " + e);
      throw e;
    }
    long tookMs = TimeUnit.NANOSECONDS.toMillis(System.nanoTime() - startNs);

    ResponseBody responseBody = response.body();
    long contentLength = responseBody.contentLength();
    String bodySize = contentLength != -1 ? contentLength + "-byte" : "unknown-length";
	//比如 <-- 200 OK http://121.40.227.8:8088/api (36ms)
    logger.log("<-- " + response.code() + ' ' + response.message() + ' '
        + response.request().url() + " (" + tookMs + "ms" + (!logHeaders ? ", "
        + bodySize + " body" : "") + ')');

    if (logHeaders) {
      Headers headers = response.headers();
      for (int i = 0, count = headers.size(); i < count; i++) {
        logger.log(headers.name(i) + ": " + headers.value(i));
      }

      if (!logBody || !HttpEngine.hasBody(response)) {
        logger.log("<-- END HTTP");
      } else if (bodyEncoded(response.headers())) {
        logger.log("<-- END HTTP (encoded body omitted)");
      } else {
        BufferedSource source = responseBody.source();
        source.request(Long.MAX_VALUE); // Buffer the entire body.
        Buffer buffer = source.buffer();

        Charset charset = UTF8;
        MediaType contentType = responseBody.contentType();
        if (contentType != null) {
          try {
            charset = contentType.charset(UTF8);
          } catch (UnsupportedCharsetException e) {
            logger.log("");
            logger.log("Couldn't decode the response body; charset is likely malformed.");
            logger.log("<-- END HTTP");

            return response;
          }
        }

        if (!isPlaintext(buffer)) {
          logger.log("");
          logger.log("<-- END HTTP (binary " + buffer.size() + "-byte body omitted)");
          return response;
        }

        if (contentLength != 0) {
          logger.log("");
			
		  //获取Response的body的字符串 并打印
          logger.log(buffer.clone().readString(charset));
        }

        logger.log("<-- END HTTP (" + buffer.size() + "-byte body)");
      }
    }

    return response;
  }

  /**
   * Returns true if the body in question probably contains human readable text. Uses a small sample
   * of code points to detect unicode control characters commonly used in binary file signatures.
   */
  static boolean isPlaintext(Buffer buffer) throws EOFException {
    try {
      Buffer prefix = new Buffer();
      long byteCount = buffer.size() < 64 ? buffer.size() : 64;
      buffer.copyTo(prefix, 0, byteCount);
      for (int i = 0; i < 16; i++) {
        if (prefix.exhausted()) {
          break;
        }
        int codePoint = prefix.readUtf8CodePoint();
        if (Character.isISOControl(codePoint) && !Character.isWhitespace(codePoint)) {
          return false;
        }
      }
      return true;
    } catch (EOFException e) {
      return false; // Truncated UTF-8 sequence.
    }
  }

  private boolean bodyEncoded(Headers headers) {
    String contentEncoding = headers.get("Content-Encoding");
    return contentEncoding != null && !contentEncoding.equalsIgnoreCase("identity");
  }
}

Then, according to HttpLoggingInterceptor, it is easy to get the content of responsebody

/**
 * @Description 异常处理 拦截器
 * Created by EthanCo on 2016/7/14.
 */
public class ErrorHandlerInterceptor implements Interceptor {
    private static final Charset UTF8 = Charset.forName("UTF-8");

    @Override
    public Response intercept(Chain chain) throws IOException {

        Request request = chain.request();
        Response response = chain.proceed(request);

        ResponseBody responseBody = response.body();
        long contentLength = responseBody.contentLength();
        
        //注意 >>>>>>>>> okhttp3.4.1这里变成了 !HttpHeader.hasBody(response)
        //if (!HttpEngine.hasBody(response)) { 
        if(!HttpHeaders.hasBody(response)){ //HttpHeader -> 改成了 HttpHeaders，看版本进行选择
		    //END HTTP
        } else if (bodyEncoded(response.headers())) {
            //HTTP (encoded body omitted)
        } else {
            BufferedSource source = responseBody.source();
            source.request(Long.MAX_VALUE); // Buffer the entire body.
            Buffer buffer = source.buffer();

            Charset charset = UTF8;
            MediaType contentType = responseBody.contentType();
            if (contentType != null) {
                try {
                    charset = contentType.charset(UTF8);
                } catch (UnsupportedCharsetException e) {
                    //Couldn't decode the response body; charset is likely malformed.
                    return response;
                }
            }

            if (!isPlaintext(buffer)) {
                L.i("<-- END HTTP (binary " + buffer.size() + "-byte body omitted)");
                return response;
            }

            if (contentLength != 0) {
                String result = buffer.clone().readString(charset);
                
				//获取到response的body的string字符串
				//do something .... <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
            }

            L.i("<-- END HTTP (" + buffer.size() + "-byte body)");
        }
        return response;
    }
	   
    static boolean isPlaintext(Buffer buffer) throws EOFException {
        try {
            Buffer prefix = new Buffer();
            long byteCount = buffer.size() < 64 ? buffer.size() : 64;
            buffer.copyTo(prefix, 0, byteCount);
            for (int i = 0; i < 16; i++) {
                if (prefix.exhausted()) {
                    break;
                }
                int codePoint = prefix.readUtf8CodePoint();
                if (Character.isISOControl(codePoint) && !Character.isWhitespace(codePoint)) {
                    return false;
                }
            }
            return true;
        } catch (EOFException e) {
            return false; // Truncated UTF-8 sequence.
        }
    }

    private boolean bodyEncoded(Headers headers) {
        String contentEncoding = headers.get("Content-Encoding");
        return contentEncoding != null && !contentEncoding.equalsIgnoreCase("identity");
    }
}