Go:udp简单使用

编写server.go

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package main

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

func handleUDPConnection(conn *net.UDPConn) {
        // 读取或写入
        buffer := make([]byte, 1024)
        n, addr, err := conn.ReadFromUDP(buffer)
        fmt.Println("UDP client : ", addr)
        fmt.Println("Received from UDP client :  ", string(buffer[:n]))
        if err != nil {
                log.Fatal(err)
        }
        // 需要在WriteToUDP()函数中指定客户端地址
        message := []byte("Hello UDP client!")
        _, err = conn.WriteToUDP(message, addr)
        if err != nil {
                log.Println(err)
        }
}

func main() {
        hostName := "localhost"
        portNum := "6000"
        service := hostName + ":" + portNum
        udpAddr, err := net.ResolveUDPAddr("udp4", service)
        if err != nil {
                log.Fatal(err)
        }
        // 设置监听
        ln, err := net.ListenUDP("udp", udpAddr)
        if err != nil {
                log.Fatal(err)
        }
        fmt.Println("UDP server up and listening on port 6000")
        defer ln.Close()
        for {
                // 等待连接
                handleUDPConnection(ln)
        }

}

编写client.go

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package main

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

 func main() {
         hostName := "localhost"
         portNum := "6000"
         service := hostName + ":" + portNum
         RemoteAddr, err := net.ResolveUDPAddr("udp", service)
         // LocalAddr := nil
         conn, err := net.DialUDP("udp", nil, RemoteAddr)
         if err != nil {
                 log.Fatal(err)
         }
         log.Printf("Established connection to %s \n", service)
         log.Printf("Remote UDP address : %s \n", conn.RemoteAddr().String())
         log.Printf("Local UDP client address : %s \n", conn.LocalAddr().String())
         defer conn.Close()
         message := []byte("Hello UDP server!")
         _, err = conn.Write(message)
         if err != nil {
                 log.Println(err)
         }
         buffer := make([]byte, 1024)
         n, addr, err := conn.ReadFromUDP(buffer)
         fmt.Println("UDP Server : ", addr)
         fmt.Println("Received from UDP server : ", string(buffer[:n]))

 }

分别运行server/client

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UDP server up and listening on port 6000
UDP client : 127.0.0.1:63937
Received from UDP client : Hello UDP server!
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2021/07/15 15:14:56 Established connection to localhost:6000
2021/07/15 15:14:56 Remote UDP address : 127.0.0.1:6000
2021/07/15 15:14:56 Local UDP client address : 127.0.0.1:63937
UDP Server : 127.0.0.1:6000
Received from UDP server : Hello UDP client!