Okhttp拦截器统一异常处理并多次读取response.body().string()

Okhttp中的response.body()只能访问一次，相信大部分人都已经踩过这个坑。在那个retrofit还没火起来的年代，大家都只是用okhttp然后自己封装，当时都是把response.body().string()用一个String保存起来随便传了。
但如今项目用的是retrofit + okhttp的网络层，在项目中打算加一个统一的异常处理，想了很久，感觉最简单的方式还是通过拦截器Interceptor的方式感觉最方便。想好了实现方式，开始好好屡一下实现的逻辑。
1、自定义拦截器，实现intercept方法
2、在intercept方法内读取json数据判断是否特定的异常统一处理
3、添加拦截器
逻辑比较简单，但是中途发现自定义处理后的后续处理不太正常

    /**
     * @Description 网络拦截器。
     **/
    private Interceptor getIns() {
        Interceptor interceptor = new Interceptor() {
            @Override
            public Response intercept(Chain chain) throws IOException {


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

                String res = response.body().string()

                Constant.LogE(TAG, " response.url():"+ url);
                Constant.LogE(TAG, " response.body():"+ res);
                BaseBean baseBean = new Gson().fromJson( res,BaseBean.class);
                if(baseBean.getState() == -401)
                {
                     //异常处理
                 }

                return response;
            }
        };
        return interceptor;
    }

经过一番调试，发现问题出在String res = response.body().string()上面。但这里又需要读取string的json数据。
看源码

  /**
   * Returns the response as a string decoded with the charset of the Content-Type header. If that
   * header is either absent or lacks a charset, this will attempt to decode the response body as
   * UTF-8.
   */
  public final String string() throws IOException {
    return new String(bytes(), charset().name());
  }

继续磕

public final byte[] bytes() throws IOException {
    long contentLength = contentLength();
    if (contentLength > Integer.MAX_VALUE) {
      throw new IOException("Cannot buffer entire body for content length: " + contentLength);
    }

    BufferedSource source = source();
    byte[] bytes;
    try {
      bytes = source.readByteArray();
    } finally {
      Util.closeQuietly(source);
    }
    if (contentLength != -1 && contentLength != bytes.length) {
      throw new IOException("Content-Length and stream length disagree");
    }
    return bytes;
  }

问题来了，桥黑板！！！划重点了！！！！
Util.closeQuietly(source);

看看源码

  /**
   * Closes {@code closeable}, ignoring any checked exceptions. Does nothing if {@code closeable} is
   * null.
   */
  public static void closeQuietly(Closeable closeable) {
    if (closeable != null) {
      try {
        closeable.close();
      } catch (RuntimeException rethrown) {
        throw rethrown;
      } catch (Exception ignored) {
      }
    }
  }

谷歌翻译下注释
关闭{@code closeable}，忽略任何已检查的异常。如果{@code closeable}是空值。

问题找到了，细看源码会发现ResponseBody类以及其他大部分类都implements Closeable。问题找到了，如何解决呢？

okhttp有个log打印类HttpLoggingInterceptor，为什么他就可以读出来而不影响传递呢？继续磕源码

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");
  }
}

好了，开始了筛选有用的代码，最后实现的代码

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

                ResponseBody responseBody = response.body();
                long contentLength = responseBody.contentLength();

                if (!bodyEncoded(response.headers())) {
                    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);
                        Constant.LogE(TAG, " response.url():"+ response.request().url());
                        Constant.LogE(TAG, " response.body():" + result);


                        }
                    }

完整的代码

    /**
     * @Description 网络拦截器
     **/
    private Interceptor getIns() {
        Interceptor interceptor = new Interceptor() {
            @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();

                if (!bodyEncoded(response.headers())) {
                    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) {
                            return response;
                        }
                    }

                    if (!isPlaintext(buffer)) {
                        return response;
                    }

                    if (contentLength != 0) {
                        String result = buffer.clone().readString(charset);
                        Constant.LogE(TAG, " response.url():"+ response.request().url());
                        Constant.LogE(TAG, " response.body():" + result);
                        //得到所需的string，开始判断是否异常
                        //***********************do something*****************************

                    }

                }


                return response;
            }
        };
        return interceptor;
    }


    private static final Charset UTF8 = Charset.forName("UTF-8");

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

    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.
        }
    }

这样封装就可以打印出来每次的请求的url及返回的json
附上添加拦截器的方式

     okHttpClient = new OkHttpClient
                    .Builder()
                    .connectTimeout(30, TimeUnit.SECONDS)//连接超时设置
                    .writeTimeout(30, TimeUnit.SECONDS)//写入超时设置，
                    .readTimeout(30, TimeUnit.SECONDS)//读取超时设置
                    .addInterceptor(getIns())//拦截器
                    .build();

感谢博主EthanCo的博客分享，此博客引用了很多其中的内容，大家可以参考参考
http://blog.csdn.net/ethanco/article/details/51908479