_, err := conn.Read(make([]byte, 0))
if err!=io.EOF{
// this connection is invalid
logger.W("conn closed....",err)
}else{
byt, _:= ioutil.ReadAll(conn);
}
注意：net: don’t return io.EOF from zero byte reads issue
参考
https://stackoverflow.com/questions/12741386/how-to-know-tcp-connection-is-closed-in-net-package