golang created logger when stepped on pit

golang created logger when stepped on pit

• Error code

package main

import (
    "fmt"
    "io"
    "log"
    "os"
)

var logger *log.Logger

func init(){
    fmt.Println("创建日记录日志文件")
    f,err:=os.OpenFile("./Log.log",os.O_WRONLY|os.O_CREATE|os.O_APPEND,0644)
    if err!=nil{
        log.Fatal("os.OpenFile err",err)
    }
    defer f.Close()
    writers := []io.Writer{
        f,
        os.Stdout}
    //实例化Writer接口
    fileAndStdoutWriter := io.MultiWriter(writers...)
    //MultiWriter创建一个Writer接口，会将提供给其的数据写入所有创建时提供的Writer接口
    logger = log.New(fileAndStdoutWriter, "", log.Ldate|log.Ltime|log.Lshortfile)
    logger.Println("---> logger:check to make sure is works")
}

func main(){
    logger.Println("注意，这里是不会打印和写入文件的")
}

• Errors

  • In the main function inside logger.Println () can not be printed to the console, you can not write to the file

• wrong reason

  defer f.Close() //在init函数执行完毕时，关闭文件f，使文件不能用于读写