golang常用的包----写日志 log包

golang提供了一个简单的日志输出包log，常用用法，已经基本满足日常的日志输出需求
1、日志级别有3个，info，fatal,panic
2、 日志文件的输出

import (
    "log"
    "os"
)
func main() {

    logFile,err:=os.Create("./log.log")
    defer logFile.Close()
    if err !=nil{
        log.Fatalln("create file log.log failed")
    }

    logger:=log.New(logFile,"[Debug]",log.Lshortfile)
    logger.Println("debug info is ,check list ,hello")
    logger.Println("debug info is ,check list ,hello000111")
    logger.SetPrefix("[Info]")
    logger.SetFlags(log.Ldate)
    logger.SetOutput(logFile)
    logger.Print("Info check")
    logger.SetOutput(os.Stdout)
    logger.Print("Info check stdout")
}

输出的结果 a.log
[Debug]main.go:45: debug info is ,check list ,hello
[Debug]main.go:46: debug info is ,check list ,hello000111
[Info]2020/09/09 Info check
标准输出：
[Info]2020/09/09 Info check stdout

样例二：

package main

import (
    "example/ch07/apps"
    "example/ch07/utils"
    "log"
    "os"
)

func main() {
    logFile,err:=os.OpenFile("./log.log",os.O_WRONLY | os.O_CREATE | os.O_APPEND,0664)
    defer logFile.Close()
    if err !=nil{
        log.Fatalln("create file log.log failed")
    }
    utils.Init(logFile)
    log.Print("Check init info")
    apps.Check()
}

package utils

import (
    "io"
    "log"
)

func Init(logFile io.Writer){
    log.SetOutput(logFile)
    log.SetPrefix("[Info]")
    log.SetFlags(log.Ldate)

}
package apps

import "log"

func Check(){
    log.Println("go to function Check")
}

输出结果为：
[Info]2020/09/09 Check init info
[Info]2020/09/09 go to function Check