总结备忘一下常用的的 Go 代码片段

遍历目录下的文件

func getFilelist(r string) {
    err := filepath.Walk(r, func(p string, f os.FileInfo, err error) error {
        if f == nil {
            return nil
        }
        if p == r || f.IsDir() {
            return nil
        }
        fmt.Println(p)
        return nil
    })
    if err != nil {
        fmt.Printf("filepath.Walk() returned %v\n", err)
    }
}

定时器

duration := 2 * time.Second
timer := time.NewTimer(duration)
go func() {
    for {
        select {
        case <-timer.C:
            fmt.Println("here")
            timer.Reset(duration)
        }
    }
}()

定时执行任务

package main

import (
    "fmt"
    "time"
)

const INTERVAL_PERIOD time.Duration = 24 * time.Hour

const HOUR_TO_TICK int = 23
const MINUTE_TO_TICK int = 00
const SECOND_TO_TICK int = 03

func main() {
    ticker := updateTicker()
    for {
        <-ticker.C
        fmt.Println(time.Now(), "- just ticked")
        ticker = updateTicker()
    }
}

func updateTicker() *time.Ticker {
    n := time.Date(time.Now().Year(), time.Now().Month(), time.Now().Day(),
        HOUR_TO_TICK, MINUTE_TO_TICK, SECOND_TO_TICK, 0, time.Local)

    if !n.After(time.Now()) {
        n = n.Add(INTERVAL_PERIOD)
    }
    fmt.Println(n, "- next tick")
    diff := n.Sub(time.Now())
    return time.NewTicker(diff)
}

读取文件

f, err := os.Open("/test.txt")
if err != nil {
    panic(err)
}
defer f.Close()
fd, err := ioutil.ReadAll(f)
if err != nil {
    panic(err)
}
fmt.Println(string(fd))

map 转 json

m := make(map[string]interface{})
m["show"] = "1"
m["content"] = "test"
j, err := json.Marshal(m)
if err != nil {
    panic(err)
}
fmt.Println(string(j))

json 转 map

var result = []byte(`
{
    "show": 1,
    "content": "test"
}`)

var r map[string]interface{}
if err := json.Unmarshal(result, &r); err != nil {
    panic(err)
}
fmt.Println(r)

写文件

func writeFile(path string, b []byte) {
    file, err := os.OpenFile(path, os.O_WRONLY|os.O_TRUNC|os.O_CREATE, 0777)
    defer file.Close()

    if err != nil {
        panic(err)
    }

    file.Write(b)
}

简单的获取 IP

func GetPulicIP() string {
    conn, _ := net.Dial("udp", "8.8.8.8:80")
    defer conn.Close()
    localAddr := conn.LocalAddr().String()
    idx := strings.LastIndex(localAddr, ":")
    return localAddr[0:idx]
}