如何使用 Go 构建一个可以接收和发送消息到多个客户端的服务器？

Question

我是 Go 新手，我正在尝试创建一个服务器，该服务器可以接收来自客户端的消息并将其发送到其他客户端或任何其他特定客户端。我尝试了很多聊天示例，但我想做的是创建两个文件，一个用于服务器，另一个用于客户端。这是我目前尝试的代码。

server.go

package main

import "net"
import "fmt"
import "bufio"
import "strings" 

func send(c net.Conn){
    netData, err := bufio.NewReader(c).ReadString('\n')
            if err != nil {
                    fmt.Println(err)
                    return
            }

    temp := strings.TrimSpace(string(netData))
    fmt.Printf(temp)        

}

func main() {

    fmt.Println("Launching server...")

    // listen on all interfaces
    ln, _ := net.Listen("tcp", ":8081")

    for {
        // Listen for an incoming connection.
        conn, err := ln.Accept()

        if err != nil {
            fmt.Println("Error accepting: ", err.Error())
            continue
        }

        go send(conn)

    } 

client.go

package main

import "net"
import "fmt"
import "bufio"
import "os"

func recieve(conn net.Conn){
    message, _ := bufio.NewReader(conn).ReadString('\n')
    fmt.Println(message)
}

func send(conn net.Conn){
    reader := bufio.NewReader(os.Stdin)

    text, _ := reader.ReadString('\n')
    fmt.Fprintf(conn, text)
}


func main(){

    // connect to this socket
    conn, err := net.Dial("tcp", "127.0.0.1:8081")
    if err != nil {
        fmt.Println("Error accepting: ", err.Error())

    }

    for {
        go recieve(conn)
        go send(conn)  
    }
    conn.Close()
}

当我尝试运行时，我的计算机崩溃了。我知道我在处理发送和接收的消息时犯了一些错误，但无法弄清楚。我将不胜感激任何帮助。谢谢。

Answer 1

我已将您的代码修改为如下所示。虽然它似乎工作 它有点原始，缺乏适当的错误处理。

server.go

package main

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

func (s *server) recvAndEcho(c io.ReadCloser) {
    defer c.Close()

    for {
        netData, err := bufio.NewReader(c).ReadString('\n')
        if err != nil {
            fmt.Println(err)
            return
        }

        temp := strings.TrimSpace(string(netData))
        fmt.Println(temp)
        s.broadcastMsg(netData)
    }
}

type server struct {
    clients []io.Writer
}

func (s *server) addClient(c net.Conn) {
    s.clients = append(s.clients, c)
}

func (s *server) broadcastMsg(msg string) {
    for _, cl := range s.clients {
        // Send the original msg back to the client
        _, err := cl.Write([]byte(fmt.Sprintf("server replied: %s\n", msg)))
        if err != nil {
            fmt.Println("server: failed to write!")
        }
    }
}

func main() {
    fmt.Println("Launching server...")
    srv := &server{}

    // listen on all interfaces
    ln, _ := net.Listen("tcp", ":8081")

    for {
        // Listen for an incoming connection.
        conn, err := ln.Accept()

        if err != nil {
            fmt.Println("Error accepting: ", err.Error())
            continue
        }
        srv.addClient(conn)
        go srv.recvAndEcho(conn)
    }
}

client.go

package main

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

func recvLoop(r io.Reader) {
    var inbuf [64]byte
    for {
        n, err := r.Read(inbuf[:])
        if err != nil {
            fmt.Println("Failed to receive msg from the server!")
            break
        }
        fmt.Print(string(inbuf[:n]))
    }
}

func main() {
    // connect to this socket
    conn, err := net.Dial("tcp", "127.0.0.1:8081")
    if err != nil {
        fmt.Println("Error accepting: ", err.Error())
        return

    }

    sc := bufio.NewScanner(os.Stdin)
    rd := bufio.NewReader(conn)
    go recvLoop(rd)

    for sc.Scan() {
        if sc.Err() != nil {
            fmt.Println("scanner error!")
        }
        txt := sc.Text()
        // It is important to append "newline" here because you are
        // using the "ReadString('\n')" method on the server side.
        // Otherwise, the program would stuck at the "readstring"
        // method.
        b := []byte(txt + "\n")
        _, err := conn.Write(b)
        if err != nil {
            fmt.Println("Failed to send data to the server!")
            break
        }
    }

    conn.Close()
}

Answer 2

我以这种方式修改了客户端。在 main 函数中调用 goroutine 函数“receive”。

package main

import (
"bufio"
"fmt"
"net"
"os"
)

func main() {
// connect to this socket
conn, err := net.Dial("tcp", "127.0.0.1:8081")
if err != nil {
    fmt.Println("Error accepting: ", err.Error())

}
go receive(conn)
sc := bufio.NewScanner(os.Stdin)


for sc.Scan() {
    if sc.Err() != nil {
        fmt.Println("scanner error!")
    }
    txt := sc.Text()
    // It is important to append "newline" here because you are
    // using the "ReadString('\n')" method on the server side.
    // Otherwise, the program would stuck at the "readstring"
    // method.
    b := []byte(txt + "\n")
    _, err := conn.Write(b)
    if err != nil {
        fmt.Println("Failed to send data to the server!")
        break
    }


}

conn.Close()
}

func receive(c net.Conn){
    rd := bufio.NewReader(c)
    var inbuf [64]byte
for{
 n, err := rd.Read(inbuf[:])

if err != nil {
        fmt.Println("Failed to receive msg from the server!")
        break
    }
    fmt.Print(string(inbuf[:n]))

}
c.Close()
}