go语言日志输出

// Bits or'ed together to control what's printed. // There is no control over the order they appear (the order listed // here) or the format they present (as described in the comments). // The prefix is followed by a colon only when Llongfile or Lshortfile // is specified. // For example, flags Ldate | Ltime (or LstdFlags) produce, // 2009/01/23 01:23:23 message // while flags Ldate | Ltime | Lmicroseconds | Llongfile produce, // 2009/01/23 01:23:23.123123 /a/b/c/d.go:23: message Ldate = 1 << iota // the date in the local time zone: 2009/01/23 Ltime // the time in the local time zone: 01:23:23 Lmicroseconds // microsecond resolution: 01:23:23.123123. assumes Ltime. Llongfile // full file name and line number: /a/b/c/d.go:23 Lshortfile // final file name element and line number: d.go:23. overrides Llongfile LUTC // if Ldate or Ltime is set, use UTC rather than the local time zone LstdFlags = Ldate | Ltime // initial values for the standard logger

Ldate                            //日期:  2009/01/23
Ltime                            // 时间:  01:23:23
Lmicroseconds              // 微秒:  01:23:23.123123.
Llongfile                       // 路径+文件名+行号: /a/b/c/d.go:23
Lshortfile                      // 文件名+行号:   d.go:23
LUTC                            // 使用标准的UTC时间格式 
LstdFlags     = Ldate | Ltime // 默认

设置默认：

log.SetFlags(log.LstdFlags)

设置日期、时间、文件名+行号（打印错误信息，比较方便定位错误点，问题定位很有用）

log.SetFlags(log.LstdFlags | Lshortfile)