golang代码片段

// 1.多goroutine间通信，channel使用
import (
    "fmt"
    "math/rand"
    "net"
    "os"
    "os/signal"
    "time"
    "crypto/sha256"
    "crypto/sha1"
    "crypto/md5"
    "strings"
)

func Producer(queue chan<- int) {
    for i := 0; i < 10; i++ {
        queue <- i
        fmt.Println("Create: ", i)
    }
}

func Consumer(queue <-chan int) {
    for i := 0; i < 10; i++ {
        v := <-queue
        fmt.Println("Receive: ", v)
    }
}
func main() {
    queue := make(chan int, 100)
    Producer(queue)
    Consumer(queue)

    time.Sleep(10 * time.Second)
}

// 2、信号使用
func SignalTest() {
    timeStart := time.Now()
    c := make(chan os.Signal)
    signal.Notify(c, os.Kill, os.Interrupt)
    s := <-c
    timeEnd := time.Now().Sub(timeStart)
    fmt.Println("Receive Signal: ", s)
    fmt.Println("耗时： ", timeEnd)

}

// 3、获取路径
func GetWd() {
    wd, err := os.Getwd()
    if err != nil {
        fmt.Println("Getwd Fail[Err:%s]", err.Error())
        return
    }

    fmt.Println(wd)
}

// 4、随机数
func GetRand() {
    r := rand.New(rand.NewSource(time.Now().UnixNano()))
    r.Intn(100) // 0~100内随机数
}

// 5、tcp连接
func GetConn() {
    conn, err := net.Dial("tcp", "localhost:8080")
    if err != nil {
        fmt.Println("Get Tcp Conn Fail[Err:%s]", err.Error())
        return
    }
    fmt.Println("连接服务器成功")
    defer conn.Close()

    ProConn(conn)

}

func ProConn(conn net.Conn) {
    sms := "hello world"
    conn.Write([]byte(sms)) // 字符串转换为byte
    buf := make([]byte, 10)
    c, err := conn.Read(buf)
    if err != nil {
        fmt.Println("Read Fail[Err:%s]", err.Error())
        return
    }
    fmt.Printf("Read Message %s", buf[0:c])
}


// 摘要

// sha256
func Digest(){
    msg := "my password"
    h := sha256.New()
    h.Write([]byte(msg))
    fmt.Println(h.Sum(nil))

    // sha1
    h = sha1.New()
    h.Write([]byte(msg))
    fmt.Println(h.Sum(nil))

    // md5
    h = md5.New()
    h.Write([]byte(msg))
    fmt.Println(h.Sum(nil))
}


// 闭包
func UseAdder() {
    var f = Adder()
    fmt.Println(f(1), "-")
    fmt.Println(f(20), "-")
    fmt.Println(f(300), "-")

}
func Adder() func(int) int {
    var x int
    return func(delta int) int {
        x += delta
        return x
    }
}