课程名称：（打造简历金牌项目）Vue+Go 开发企业级微服务网关项目
课程章节：2-9 2-10
课程讲师：牛儿吃草

课程内容：
GoLang创建udp的客户端和服务端

UDP Client

package main

import (
	"fmt"
	"net"
)

func main() {
	//step 1 连接服务器
	conn, err := net.DialUDP("udp", nil, &net.UDPAddr{
		IP:   net.IPv4(127, 0, 0, 1),
		Port: 9090,
	})

	if err != nil {
		fmt.Printf("connect failed, err: %v\n", err)
		return
	}

	for i := 0; i < 100; i++ {
		//step 2 发送数据
		_, err = conn.Write([]byte("hello server!"))
		if err != nil {
			fmt.Printf("send data failed, err : %v\n", err)
			return
		}

		//step 3 接收数据
		result := make([]byte, 1024)
		n, remoteAddr, err := conn.ReadFromUDP(result)
		if err != nil {
			fmt.Printf("receive data failed, err: %v\n", err)
			return
		}
		fmt.Printf("receive from addr: %v  data: %v\n", remoteAddr, string(result[:n]))
	}
}

UDP Server

package main

import (
	"fmt"
	"net"
)

func main() {
	//step 1 监听服务器
	listen, err := net.ListenUDP("udp", &net.UDPAddr{
		IP:   net.IPv4(0, 0, 0, 0),
		Port: 9090,
	})
	if err != nil {
		fmt.Printf("listen failed, err:%v\n", err)
		return
	}

	//step 2 循环读取消息内容
	for {
		var data [1024]byte
		n, addr, err := listen.ReadFromUDP(data[:])
		if err != nil {
			fmt.Printf("read failed from addr: %v, err: %v\n", addr, err)
			break
		}

		go func() {
			//todo sth
			//step 3 回复数据
			fmt.Printf("addr: %v data: %v  count: %v\n", addr, string(data[:n]), n)
			_, err = listen.WriteToUDP([]byte("received success!"), addr)
			if err != nil {
				fmt.Printf("write failed, err: %v\n", err)
			}
		}()
	}
}

创建TCP 客户端和服务端

tcpclient

package main 

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

func main()  {
	doSend()
	fmt.Print("doSend over")
	doSend()
	fmt.Print("doSend over")
	//select {}
}


func doSend() {
	//1、连接服务器
	conn, err := net.Dial("tcp", "localhost:9090")
	if err != nil {
		fmt.Printf("connect failed, err : %v\n", err.Error())
		return
	}
	defer conn.Close()	//思考题：这里不填写会有啥问题？
	//2、读取命令行输入
	inputReader := bufio.NewReader(os.Stdin)
	for {
		// 3、一直读取直到读到\n
		input, err := inputReader.ReadString('\n')
		if err != nil {
			fmt.Printf("read from console failed, err: %v\n", err)
			break
		}
		// 4、读取Q时停止
		trimmedInput := strings.TrimSpace(input)
		if trimmedInput == "Q" {
			break
		}
		// 5、回复服务器信息
		_, err = conn.Write([]byte(trimmedInput))
		if err != nil {
			fmt.Printf("write failed , err : %v\n", err)
			break
		}
	}
}

tcpserver

package main

import (
	"fmt"
	"net"
)

func main() {
	//1、监听端口
	listener, err := net.Listen("tcp", "0.0.0.0:9090")
	if err != nil {
		fmt.Printf("listen fail, err: %v\n", err)
		return
	}

	//2.建立套接字连接
	for {
		conn, err := listener.Accept()
		if err != nil {
			fmt.Printf("accept fail, err: %v\n", err)
			continue
		}

		//3. 创建处理协程
		go process(conn)
	}
}

func process(conn net.Conn) {
	defer conn.Close()	//思考题：这里不填写会有啥问题？
	for {
		var buf [128]byte
		n, err := conn.Read(buf[:])

		if err != nil {
			fmt.Printf("read from connect failed, err: %v\n", err)
			break
		}
		str := string(buf[:n])
		fmt.Printf("receive from client, data: %v\n", str)
	}
}

课程收获：

• 通过前一阶段udp和tcp相关理论的学习，以及今天的udp客户端，服务端、tcp客户端，服务端的代码实现，终于将之前所学理论和实际操作相结合。