场景
在不同的开发机器上，建立HTTP1.1连接，有的机器会进行一两次交互后，会检测到断开连接。这种情况下，会需要重连服务器。一般断开的原因包括硬件/路由/代理服务器。
目前尝试添加Keep-Alive字段，目前来看估计跟机器有关
摘自
You are assuming that the connection is staying open after each HTTP response is received, but that is
not guaranteed. You have to look at the server's actual HTTP response (specifically, at the HTTP
version reported in the status line, and at the Connection header) to know if the server is leaving the
connection open or not.
You are sending an HTTP 1.1 request, but there is no guarantee that the server will reply with an HTTP
1.1 response.
If the response is using HTTP 0.9, you must close the socket and reconnect before sending the next HTTP
request.
If the response is using HTTP 1.0, and if the Connection header does not say keep-alive, then you must
close the socket and reconnect before sending the next HTTP request.
If the response is using HTTP 1.1, and if the Connection header does not say close, then the server
left the connection open on its end, and you can reuse the same connection for the next request.
However, you do still need to take into account the possibility that the connection might be closed
externally (by a firewall/router/proxy, etc) before you actually send the next HTTP request.
So in the case of either HTTP 1.0 or 1.1, if you are expecting the connection to remain open, but send
() fails with an error indicating the connection was lost, simply close the socket and reconnect and
then send the same HTTP request again.
原文地址：http://blog.51cto.com/fengyuzaitu/2118231