go tcp通信

----tcp 客户端

package main

import (
    "net"
    "fmt"
)

func main()  {
    conn,err := net.Dial("tcp","127.0.0.1:8101")
    if err != nil{
        fmt.Println("err=",err)
        return
    }
    defer conn.Close()

    //发送数据
    conn.Write([]byte("hello world,I learn go!"))

}

---tcp服务器

package main

import (
    "net"
    "fmt"

    "strings"
)

func HandleConn(conn net.Conn)  {
   //函数调用完毕，自动关闭conn
   defer conn.Close()

   //获取客户端网络地址信息
   addr := conn.RemoteAddr().String()
   fmt.Println(addr," connect sucessful")
   buf := make([]byte,)

   for{
        n,err := conn.Read(buf)
        if err != nil{
            fmt.Println("err=",err)
            return
        }
        fmt.Printf("[%s]:%s\n",addr,string(buf[:n]))
        fmt.Println("len=",len(string(buf[:n])))

        if "exit" == string(buf[:n-]) {  //"\r\n"
            fmt.Println(addr,"exit")
            return
        }

        //把用户小写转换成大写 在发送给用户
        conn.Write([]byte(strings.ToUpper(string(buf[:n]))))
   }

}

func main()  {
    //监听
    listener,err := net.Listen("tcp","127.0.0.1:8000")
    if err != nil{
        fmt.Println("err=",err)
        return
    }
    defer listener.Close()
   //接收多个用户
   for {
         conn,err := listener.Accept()
         if err != nil{
             fmt.Println("err=",err)
             return
      }
      //处理用户请求，新建立一个协程
      go  HandleConn(conn)
   }

}