Golang代碼蒐集-簡易聊天服務器

這段代碼出自《Go程序設計語言》（英文版）第254頁，一段很簡單的代碼實現了一個簡易的聊天服務器。裏面涉及了tcp通訊、輸入/輸出、使用chan傳值等。

//服務器代碼
package main

import (
    "bufio"
    "fmt"
    "io"
    "log"
    "net"
)

func main() {
    listener, err := net.Listen("tcp", ":8000")
    if err != nil {
        log.Fatal(err)
    }
    fmt.Println("Server listens successfull and gets ready for acceptions")
    go broadcaster()
    for {
        conn, err := listener.Accept()
        if err != nil {
            log.Fatal(err)
        }
        fmt.Printf("[%v] connected \n", conn.RemoteAddr())
        go handleConn(conn)
    }
}

type client chan<- string

var (
    entering = make(chan client)
    leaving  = make(chan client)
    message  = make(chan string)
)

func broadcaster() {
    clients := make(map[client]bool)
    for {
        select {
        case msg := <-message:
            for cli := range clients {
                cli <- msg
            }
        case cli := <-entering:
            clients[cli] = true
        case cli := <-leaving:
            delete(clients, cli)
            close(cli)
        }
    }
}
func handleConn(c net.Conn) {
    defer c.Close()
    ch := make(chan string)
    go clientWriter(c, ch)
    ch <- "Welcome!\n"
    entering <- ch
    message <- fmt.Sprintf("[%v] in \n", c.RemoteAddr())
    input := bufio.NewScanner(c)
    for input.Scan() {
        message <- fmt.Sprintf("[%v] say: %v \n", c.RemoteAddr(), input.Text())
    }
    leaving <- ch
    message <- fmt.Sprintf("[%v] out \n", c.RemoteAddr())
    fmt.Printf("[%v] disconnected \n", c.RemoteAddr())
}
func clientWriter(c net.Conn, ch <-chan string) {
    for msg := range ch {
        io.WriteString(c, msg)
    }

}

//客戶端
package main

import (
    "io"
    "log"
    "net"
    "os"
)

func main() {
    conn, err := net.Dial("tcp", ":8000")
    if err != nil {
        log.Fatal(err)
    }
    go mustCopy(os.Stdout, conn)
    mustCopy(conn, os.Stdin)
}
func mustCopy(dest io.Writer, src io.Reader) {
    if _, err := io.Copy(dest, src); err != nil {
        log.Fatal(err)
    }
}