一个简单的golang实现的私聊，由服务器端决定两两匹配
服务器端 chat_server.go

package main


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


const listenAddr = "localhost:4000"

func main() {
    l,err := net.Listen("tcp",listenAddr)
    if err != nil {
        log.Fatal(err)
    }
    for {
        c,err := l.Accept()
        if err != nil {
        log.Fatal(err)
    }
    //go io.Copy(c,c)
    go match(c)
    }
}


var partner = make(chan io.ReadWriteCloser)


func match(c io.ReadWriteCloser) {
    fmt.Fprint(c,"Waiting for a partner...")
    select {
    case partner <- c:
        // now handled by the other goroutine
    case p := <-partner:
    chat(p,c)
    }
}


/*
func chat(a,b io.ReadWriteCloser) {
    fmt.Fprintln(a,"Found one! Say hi.")
    fmt.Fprintln(b,"Found one! Say hi.")
    go io.Copy(a,b)
    io.Copy(b,a)
}
*/


func chat(a,"Found one! Say hi.")
    errc := make(chan error,1)
    go cp(a,b,errc)
    go cp(b,a,errc)
    if err := <-errc; err != nil {
        log.Println(err)
    }
    a.Close()
    b.Close()
}

func cp(w io.Writer,r io.Reader,errc chan<- error)        {
    _,err := io.Copy(w,r)
    errc <- err
}

客户端chat_client.go:

package main
import (
    "fmt"
    "log"
    "net"
)

func main() {
    l,err := net.Dial("tcp","localhost:4000")
    if err != nil {
        log.Fatal(err)
    }
    go send(l)
    for {
        datas := make([]byte,255)
        n,err := l.Read(datas)
        if err != nil {
            log.Fatal(err)
        }
    fmt.Println(string(datas[0:n]))
    }   
}


func send(l net.Conn){
    sms := make([]byte,255)
    for{
        //fmt.Print("请输入要发送的消息：")
        _,err := fmt.Scan(&sms)
        if err != nil {
            fmt.Println("数据输入异常:",err.Error())
        }

        l.Write(sms)
    }
}