golang之log

标准库log

golang实现了简单易用的log，可以满足基本需求。虽然标准库实现了syslog，但已冻结不增加新功能。

Package log implements a simple logging package. It defines a type, Logger, with methods for formatting output. It also has a predefined 'standard' Logger accessible through helper functions Print[f|ln], Fatal[f|ln], and Panic[f|ln], which are easier to use than creating a Logger manually. That logger writes to standard error and prints the date and time of each logged message. Every log message is output on a separate line: if the message being printed does not end in a newline, the logger will add one.

The Fatal functions call os.Exit(1) after writing the log message. The Panic functions call panic after writing the log message.

log常用的函数是Print[f|ln]，Fatal[f|ln]和Panic[f|ln]

func Flags() int获取flag，func Prefix() string获取前缀，SefFlags(flag int)和SetPrefix(prefix string)用于设置。

These flags define which text to prefix to each log entry generated by the Logger.  flags常量如下：

const (
    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
    Lmsgprefix                    // move the "prefix" from the beginning of the line to before the message
    LstdFlags     = Ldate | Ltime // initial values for the standard logger
)

标准logger接口

type Logger    func New(out io.Writer, prefix string, flag int) *Logger

type Logger
    func New(out io.Writer, prefix string, flag int) *Logger
    func (l *Logger) Fatal(v ...interface{})
    func (l *Logger) Fatalf(format string, v ...interface{})
    func (l *Logger) Fatalln(v ...interface{})
    func (l *Logger) Flags() int
    func (l *Logger) Output(calldepth int, s string) error
    func (l *Logger) Panic(v ...interface{})
    func (l *Logger) Panicf(format string, v ...interface{})
    func (l *Logger) Panicln(v ...interface{})
    func (l *Logger) Prefix() string
    func (l *Logger) Print(v ...interface{})
    func (l *Logger) Printf(format string, v ...interface{})
    func (l *Logger) Println(v ...interface{})
    func (l *Logger) SetFlags(flag int)
    func (l *Logger) SetOutput(w io.Writer)
    func (l *Logger) SetPrefix(prefix string)
    func (l *Logger) Writer() io.Writer

type Logger