注意字符串不能和数字直接拼接
str := "Starting the server,port="+strconv.Itoa(port)
切片转字符串 string(buf)

go run echo-server.go -port=8888



package main

import (
    "net"
    "fmt"
    "io"
    "flag"
    "strconv"
)

func main() {
    var port int
    flag.IntVar(&port, "port", 8888, "port")
    flag.Parse()
    
    listener, err := net.Listen("tcp", "127.0.0.1:"+strconv.Itoa(port))
    if err != nil {
        panic("error listen: " + err.Error())
    }
    fmt.Println("Starting the server,port="+strconv.Itoa(port))

    for {
        conn, err := listener.Accept()
        if err != nil {
            panic("error accept: " + err.Error())       
        }
        fmt.Println("Accept the connection: ", conn.RemoteAddr())
        go echoServer(conn)
    }
}

func echoServer(conn net.Conn) {
    buf := make([]byte, 1024)
    defer conn.Close()

    for {
        n, err := conn.Read(buf)
        switch err {
            case nil:
                conn.Write(buf[0:n])
            case io.EOF:
                fmt.Printf("Warning: End of data %s\n", err)
                return
            default:
                fmt.Printf("Error: read data %s\n", err)
                return
        }
        fmt.Println(conn.RemoteAddr(),string(buf))
    }
}


https://gitee.com/dyyx/hellocode/blob/master/web/tech/go/demo/echo-server.go