Chrome Debug Protocol--Network enable后websocket如何接受数据(五)

// ***************************************************************
// 3. 启动NetWork,发送报文({"id":1,"method":"Network.enable","params":{}})
//    那websocket又是如何接受数据,并改变:InvocationResult对象的呢?
//    入口即在:ChromeDevToolsServiceImpl的构造器里
// ***************************************************************
network.enable();

// ... ...

public ChromeDevToolsServiceImpl(
      WebSocketService webSocketService, 
      ChromeDevToolsServiceConfiguration configuration)
  throws WebSocketServiceException {
  // websocket client  
  this.webSocketService = webSocketService;
  this.configuration = configuration;

  this.eventExecutorService = configuration.getEventExecutorService();

  this.closeLatch = new CountDownLatch(1);

  // ********************************************************************
  // 4. 为websocket配置Hnalder,而对应的业务为:ChromeDevToolsServiceImpl
  //    因为:ChromeDevToolsServiceImpl还实现了:Consumer<String>方法
  // ********************************************************************
  this.webSocketService.addMessageHandler(this);
}// end 构造器

public void addMessageHandler(
    Consumer<String> consumer) throws WebSocketServiceException {
    // session在ChromeDevToolsService.createDevToolsService就已经初化了的.
    if (session == null) { // false
      throw new WebSocketServiceException(
          "You first must connect to ws server in order to receive messages.");
    }

    // 如果已经配置了MessageHandler,则抛出异常
    if (!session.getMessageHandlers().isEmpty()) { // false
      throw new WebSocketServiceException("You are already subscribed to this web socket service.");
    }

    // 配置MessageHandler
    session.addMessageHandler(
        new MessageHandler.Whole<String>() {
          @Override
          public void onMessage(String message) {
            LOGGER.debug("Received message {} on {}", message, session.getRequestURI());
            // *******************************************************
            // 5. 调用:consumer.accept == ChromeDevToolsServiceImpl.accept方法
            // *******************************************************
            consumer.accept(message);
          }
        });
}//end addMessageHandler

public void accept(String message) {
  // 报文内容:
  // message = {"id":1,"result":{}}
    try {

      JsonNode jsonNode = OBJECT_MAPPER.readTree(message);
      // 获得ID
      JsonNode idNode = jsonNode.get(ID_PROPERTY);
      if (idNode != null) {
        // id = 1
        Long id = idNode.asLong();
        // 从Map中获取ID对应的:InvocationResult
        InvocationResult invocationResult = invocationResultMap.get(id);

        // 调用:InvocationResult相关方法,告之是否成功,以及报文内容.
        if (invocationResult != null) {
          JsonNode resultNode = jsonNode.get(RESULT_PROPERTY);
          JsonNode errorNode = jsonNode.get(ERROR_PROPERTY);

          if (errorNode != null) {
            invocationResult.signalResultReady(false, errorNode);
          } else {
            if (invocationResult.getReturnProperty() != null) {
              if (resultNode != null) {
                resultNode = resultNode.get(invocationResult.getReturnProperty());
              }
            }

            if (resultNode != null) {
              invocationResult.signalResultReady(true, resultNode);
            } else {
              invocationResult.signalResultReady(true, null);
            }
          }
        } else {
          LOGGER.warn(
              "Received result response with unknown invocation id {}. {}", id, jsonNode.asText());
        }
      } else {  //报文体中不存在id

        // 那就可能是事件
        // Network.requestWillBeSent
        // Network.requestWillBeSentExtraInfo
        // 
        JsonNode methodNode = jsonNode.get(METHOD_PROPERTY);

        // {"requestId":"9109BD8473893CFB540FBB1B48B77498","loaderId":"9109BD8473893CFB540FBB1B48B77498","documentURL":"http://github.com/","request":{"url":"http://github.com/","method":"GET","headers":{"Upgrade-Insecure-Requests":"1","User-Agent":"Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/87.0.4280.88 Safari/537.36"},"mixedContentType":"none","initialPriority":"VeryHigh","referrerPolicy":"no-referrer-when-downgrade"},"timestamp":8503.432429,"wallTime":1.607327182175508E9,"initiator":{"type":"other"},"type":"Document","frameId":"7B009B704DDF902D64F73CDDD50BE519","hasUserGesture":false}
        JsonNode paramsNode = jsonNode.get(PARAMS_PROPERTY);

        if (methodNode != null) {
          // 调用相应的:
          handleEvent(methodNode.asText(), paramsNode);
        }
      }
    } catch (IOException ex) {
      LOGGER.error("Failed reading web socket message!", ex);
    } catch (Exception ex) {
      LOGGER.error("Failed receiving web socket message!", ex);
    }
} // end accept


private void handleEvent(String name, JsonNode params) {
    //  根据事件名称(Network.requestWillBeSent),获取到相应的:EventListenerImpl进行处理.
    Set<EventListenerImpl> listeners = eventNameToHandlersMap.get(name);
    if (listeners != null) {
      final Set<EventListener> eventListeners;
      synchronized (listeners) {
        eventListeners = new HashSet<>(listeners);
      }

      if (!eventListeners.isEmpty()) {
        eventExecutorService.execute(
            () -> {
              Object event = null;

              for (EventListenerImpl listener : listeners) {
                try {
                  if (event == null) {
                    event = readJsonObject(listener.getParamType(), params);
                  }

                  listener.getHandler().onEvent(event);
                } catch (Exception e) {
                  LOGGER.error("Error while processing event {}", name, e);
                }
              }
            });
      }
    }
} // end handleEvent