My go study notes (1) - write a log

write log

---

The first method:
write a method that will open and close the file every time a log is written

func Mylog(v ...interface{}) {
    f, err := os.OpenFile("test.log", os.O_RDWR|os.O_CREATE|os.O_APPEND, 0666)
    check(err)
    defer f.Close()
    logger := log.New(f, TAG, log.Ldate|log.Ltime|log.Lmicroseconds)
    logger.Println(v...)
}

The following is to support the form input of Println

func Mylog(v ...interface{})

The TAG in the parameters below can be customized to any keyword, while adding date-time-milliseconds.

const TAG = "main: "
logger := log.New(f, TAG, log.Ldate|log.Ltime|log.Lmicroseconds)

Running result: in test.log

main: 2018/04/26 11:03:12.343476 这是第一条日志
main: 2018/04/26 11:03:12.418434 这是第二条日志

The file name is
modified

f, err := os.OpenFile("test.log", os.O_RDWR|os.O_CREATE|os.O_APPEND, 0666)

for

t := time.Now().Format("2006-01-02")
name := "test_" + t + ".log"
f, err := os.OpenFile(name, os.O_RDWR|os.O_CREATE|os.O_APPEND, 0666)

---

The second method:
open the file at one time, record the log directly every time, and do the log level processing at the same time.
filenamemylog.go

package mylog

import (
    "fmt"
    "log"
    "os"
    "time"
)

var (
    logi *log.Logger
    logd *log.Logger
    loge *log.Logger
    logw *log.Logger
    f    *os.File
)

func Init() {
    t := time.Now().Format("2006-01-02")
    name := "test_" + t + ".log"
    var e error
    f, e = os.OpenFile(name, os.O_RDWR|os.O_CREATE|os.O_APPEND, 0666)
    if e != nil {
        fmt.Println("error:", e.Error())
    }
    logi = log.New(f, "INFO : ", log.Ldate|log.Ltime|log.Lmicroseconds)
    logd = log.New(f, "DEBUG: ", log.Ldate|log.Ltime|log.Lmicroseconds)
    loge = log.New(f, "ERROR: ", log.Ldate|log.Ltime|log.Lmicroseconds)
    logw = log.New(f, "WARN : ", log.Ldate|log.Ltime|log.Lmicroseconds)
}
func Close() {
    f.Close()
}

func LogI(v ...interface{}) {
    logi.Println(v...)
}
func LogD(v ...interface{}) {
    logd.Println(v...)
}
func LogE(v ...interface{}) {
    loge.Println(v...)
}
func LogW(v ...interface{}) {
    logw.Println(v...)
}

application

mylog.Init()
mylog.LogI("这是第二种方法日志")
mylog.LogE("这是第二种方法日志")
mylog.LogD("这是第二种方法日志")
mylog.LogW("这是第二种方法日志")
mylog.Close()

Output effect file:

INFO : 2018/04/26 11:59:56.227440 这是第二种方法日志
ERROR: 2018/04/26 11:59:56.228440 这是第二种方法日志
DEBUG: 2018/04/26 11:59:56.228440 这是第二种方法日志
WARN : 2018/04/26 11:59:56.228440 这是第二种方法日志

---

The third method:
create a class, then create an object, and encapsulate the method.
document:

package mylog

import (
    "fmt"
    "log"
    "os"
    "time"
)

type MLog struct {
    isInit bool
    logi   *log.Logger
    logd   *log.Logger
    loge   *log.Logger
    logw   *log.Logger
    f      *os.File
}

func (l *MLog) init() {
    t := time.Now().Format("2006-01-02")
    name := "test_" + t + ".log"
    var e error
    l.f, e = os.OpenFile(name, os.O_RDWR|os.O_CREATE|os.O_APPEND, 0666)
    if e != nil {
        fmt.Println("error:", e.Error())
    }
    l.logi = log.New(l.f, "INFO : ", log.Ldate|log.Ltime|log.Lmicroseconds)
    l.logd = log.New(l.f, "DEBUG: ", log.Ldate|log.Ltime|log.Lmicroseconds)
    l.loge = log.New(l.f, "ERROR: ", log.Ldate|log.Ltime|log.Lmicroseconds)
    l.logw = log.New(l.f, "WARN : ", log.Ldate|log.Ltime|log.Lmicroseconds)
    l.isInit = true
}
func (l *MLog) Close() {
    if l.isInit {
        l.f.Close()
    }
}

func (l *MLog) I(v ...interface{}) {
    if !l.isInit {
        l.init()
    }
    l.logi.Println(v...)
}
func (l *MLog) D(v ...interface{}) {
    if !l.isInit {
        l.init()
    }
    l.logd.Println(v...)
}
func (l *MLog) E(v ...interface{}) {
    if !l.isInit {
        l.init()
    }
    l.loge.Println(v...)
}
func (l *MLog) W(v ...interface{}) {
    if !l.isInit {
        l.init()
    }
    l.logw.Println(v...)
}

application

mlog = new(mylog.MLog)
mlog.I("这是第三种方法")
mlog.D("这是第三种方法")
mlog.E("这是第三种方法")
mlog.W("这是第三种方法")
mlog.Close()

output result

INFO : 2018/04/26 12:38:19.258334 这是第三种方法
DEBUG: 2018/04/26 12:38:19.259334 这是第三种方法
ERROR: 2018/04/26 12:38:19.259334 这是第三种方法
WARN : 2018/04/26 12:38:19.259334 这是第三种方法