Http1.1协议标准：
If an HTTP/1.1 client sends a request which includes a request body, but which does not include an Expect request-header field with the “100-continue” expectation, and if the client is not directly connected to an HTTP/1.1 origin server, and if the client sees the connection close before receiving any status from the server, the client SHOULD retry the request.
大致意思就是说，如果发送一个请求到服务器端，该请求有请求体，但是请求头里面不包含“ 100-continue ”这种东西，并且客户端没有直接连接到原始的 HTTP/1.1 服务器，此时，如果客户端在接收到服务器发送的 HTTP 状态之前发现服务器主动关掉连接，那么客户端应该重试请求。
版权声明：本文为weixin_40648117原创文章，遵循 CC 4.0 BY-SA 版权协议，转载请附上原文出处链接和本声明。