长连接,在页面里嵌入一个隐蔵ifr a me，将这个隐蔵ifr a me的src属性设为对一个长连接的请求，服务器端就能源源不断地往客户端输入数据。Gmail聊天实例-Long connection, embedding a hidden ifr a me in the page Zao, Zao this hidden ifr a me src attribute is set for a long connection request, the server can be an endles