code: @Override
      public ProxyTuple randomProxy(){
          synchronized (this.proxys){
              if (this.proxys.size() == 0) {
                  return null;
              }
              Map.Entry<String,Integer> entity = this.proxys.entrySet().stream().collect(Collectors.toList()).get(random.nextInt(proxys.size()));
              return new ProxyTuple(entity.getKey(), entity.getValue());
          }
      }
docs: 随机获取一个代理
  @return