Go语言快速上手 | 青训营笔记

对前两节课的稍微总结。感觉基础讲的算是比较快的，需要自己私下学习。三个项目代码思路不算难，但是对于不熟悉相关库的使用的我，跟上还是比较难。目前想法是混个眼熟，用的时候即拿即用，现在做个笔记巩固一下~~~

课程源码：github.com/wangkechun/…

短链接：hi-hi.cn/go

01 简介

1. 高性能、高并发
2. 语法简单、学习曲线平缓
3. 丰富的标准库
4. 完善的工具链
5. 静态链接
6. 快速编译
7. 跨平台
8. 垃圾回收

02 入门

1. 开发环境：个人感觉选择GoLand比较方便
2. 基础语法：变量、if - else、循环、switch、数组、切片、map、range、函数、指针、结构体、结构体方法、错误处理、字符串操作、字符串格式化、JSON处理、时间处理、数字解析、进程信息

03 实战

1. 猜谜游戏

   • "math/rand"库 —— rand.Seed(time.Now().UnixNano())，rand.Intn(maxNum)

   • "bufio"库

      reader := bufio.NewReader(os.Stdin)
      input, err := reader.ReadString('\n')
      if err != nil {
          fmt.Println("An error occurred while reading input. Please try again.", err)
          return
      }
      input = strings.TrimSuffix(input, "\n") // 去掉换行符
     

   • "time"库 —— time.Now()

   • "strconv"库 —— guess, err := strconv.Atoi(input)

   代码

   package main
   
   import (
      //"bufio"
      "fmt"
      "math/rand"
      //"os"
      "strconv"
      "strings"
      "time"
   )
   
   func main() {
      maxNum := 100
      rand.Seed(time.Now().UnixNano())
      secretNumber := rand.Intn(maxNum)
      //fmt.Println("The secret number is", secretNumber)
   
      fmt.Println("Please input your guess")
      //reader := bufio.NewReader(os.Stdin)
      for {
         var input string
         fmt.Scanf("%s\n", &input) //使用fmt.Scanf来简化代码实现
         //input, err := reader.ReadString('\n')
         /*if err != nil {
            fmt.Println("An error occurred while reading input. Please try again.", err)
            continue
         }*/
         input = strings.TrimSuffix(input, "\r\n")
   
         guess, err := strconv.Atoi(input)
         if err != nil {
            fmt.Println("Invalid input. Please enter an integer value.")
            continue
         }
         fmt.Println("Your guess is", guess)
         if guess > secretNumber {
            fmt.Println("Your guess is bigger than the secret number. Please try again.")
         } else if guess < secretNumber {
            fmt.Println("Your guess is smaller than the secret number. Please try again.")
         } else {
            fmt.Println("Correct, you Legend!")
            break
         }
      }
   }
   

2. 在线词典

   • 对请求 —— copy as cURL

   • 将curl命令转换成代码 —— Convert curl to Go (curlconverter.com)

     • 创建请求：http.NewRequest()
     • 设置请求头：req.Header.Set()
     • 发起请求：client.Do()
     • 读取相应：ioutil.ReadAll()

   • 根据响应生成reaquest body —— JSON转Golang Struct - 在线工具 - OKTools

运行方法（举例）：go run main.go hello

package main

import (
   "bytes"
   "encoding/json"
   "fmt"
   "io/ioutil"
   "log"
   "net/http"
   "os"
)

type DictRequest struct {
   TransType string `json:"trans_type"`
   Source    string `json:"source"`
   UserID    string `json:"user_id"`
}

type DictResponse struct {
   Rc   int `json:"rc"`
   Wiki struct {
      KnownInLaguages int `json:"known_in_laguages"`
      Description     struct {
         Source string      `json:"source"`
         Target interface{} `json:"target"`
      } `json:"description"`
      ID   string `json:"id"`
      Item struct {
         Source string `json:"source"`
         Target string `json:"target"`
      } `json:"item"`
      ImageURL  string `json:"image_url"`
      IsSubject string `json:"is_subject"`
      Sitelink  string `json:"sitelink"`
   } `json:"wiki"`
   Dictionary struct {
      Prons struct {
         EnUs string `json:"en-us"`
         En   string `json:"en"`
      } `json:"prons"`
      Explanations []string      `json:"explanations"`
      Synonym      []string      `json:"synonym"`
      Antonym      []string      `json:"antonym"`
      WqxExample   [][]string    `json:"wqx_example"`
      Entry        string        `json:"entry"`
      Type         string        `json:"type"`
      Related      []interface{} `json:"related"`
      Source       string        `json:"source"`
   } `json:"dictionary"`
}

func query(word string) {
   client := &http.Client{}
   request := DictRequest{TransType: "en2zh", Source: word}
   buf, err := json.Marshal(request)
   if err != nil {
      log.Fatal(err)
   }
   var data = bytes.NewReader(buf)
   req, err := http.NewRequest("POST", "https://api.interpreter.caiyunai.com/v1/dict", data)
   if err != nil {
      log.Fatal(err)
   }
   req.Header.Set("Connection", "keep-alive")
   req.Header.Set("DNT", "1")
   req.Header.Set("os-version", "")
   req.Header.Set("sec-ch-ua-mobile", "?0")
   req.Header.Set("User-Agent", "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/99.0.4844.51 Safari/537.36")
   req.Header.Set("app-name", "xy")
   req.Header.Set("Content-Type", "application/json;charset=UTF-8")
   req.Header.Set("Accept", "application/json, text/plain, */*")
   req.Header.Set("device-id", "")
   req.Header.Set("os-type", "web")
   req.Header.Set("X-Authorization", "token:qgemv4jr1y38jyq6vhvi")
   req.Header.Set("Origin", "https://fanyi.caiyunapp.com")
   req.Header.Set("Sec-Fetch-Site", "cross-site")
   req.Header.Set("Sec-Fetch-Mode", "cors")
   req.Header.Set("Sec-Fetch-Dest", "empty")
   req.Header.Set("Referer", "https://fanyi.caiyunapp.com/")
   req.Header.Set("Accept-Language", "zh-CN,zh;q=0.9")
   req.Header.Set("Cookie", "_ym_uid=16456948721020430059; _ym_d=1645694872")
   resp, err := client.Do(req)
   if err != nil {
      log.Fatal(err)
   }
   defer resp.Body.Close()
   bodyText, err := ioutil.ReadAll(resp.Body)
   if err != nil {
      log.Fatal(err)
   }
   if resp.StatusCode != 200 {
      log.Fatal("bad StatusCode:", resp.StatusCode, "body", string(bodyText))
   }
   var dictResponse DictResponse
   err = json.Unmarshal(bodyText, &dictResponse)
   if err != nil {
      log.Fatal(err)
   }
   fmt.Println(word, "UK:", dictResponse.Dictionary.Prons.En, "US:", dictResponse.Dictionary.Prons.EnUs)
   for _, item := range dictResponse.Dictionary.Explanations {
      fmt.Println(item)
   }
}

func main() {
   if len(os.Args) != 2 {
      fmt.Fprintf(os.Stderr, `usage: simpleDict WORD
example: simpleDict hello
      `)
      os.Exit(1)
   }
   word := os.Args[1]
   query(word)
}

3. SOCKS5代理介绍

测试方式：

• 代码目录下：go run main.go
• 开启另一个终端：curl --socks5 127.0.0.1:1080 -v www.qq/com

package main

import (
   "bufio"
   "context"
   "encoding/binary"
   "errors"
   "fmt"
   "io"
   "log"
   "net"
)

const socks5Ver = 0x05
const cmdBind = 0x01
const atypeIPV4 = 0x01
const atypeHOST = 0x03
const atypeIPV6 = 0x04

func main() {
   server, err := net.Listen("tcp", "127.0.0.1:1080")
   if err != nil {
      panic(err)
   }
   for {
      client, err := server.Accept()
      if err != nil {
         log.Printf("Accept failed %v", err)
         continue
      }
      go process(client)
   }
}

func process(conn net.Conn) {
   defer conn.Close()
   reader := bufio.NewReader(conn)
   err := auth(reader, conn)
   if err != nil {
      log.Printf("client %v auth failed:%v", conn.RemoteAddr(), err)
      return
   }
   err = connect(reader, conn)
   if err != nil {
      log.Printf("client %v auth failed:%v", conn.RemoteAddr(), err)
      return
   }
}

func auth(reader *bufio.Reader, conn net.Conn) (err error) {
   // +----+----------+----------+
   // |VER | NMETHODS | METHODS  |
   // +----+----------+----------+
   // | 1  |    1     | 1 to 255 |
   // +----+----------+----------+
   // VER: 协议版本，socks5为0x05
   // NMETHODS: 支持认证的方法数量
   // METHODS: 对应NMETHODS，NMETHODS的值为多少，METHODS就有多少个字节。RFC预定义了一些值的含义，内容如下:
   // X’00’ NO AUTHENTICATION REQUIRED
   // X’02’ USERNAME/PASSWORD

   ver, err := reader.ReadByte()
   if err != nil {
      return fmt.Errorf("read ver failed:%w", err)
   }
   if ver != socks5Ver {
      return fmt.Errorf("not supported ver:%v", ver)
   }
   methodSize, err := reader.ReadByte()
   if err != nil {
      return fmt.Errorf("read methodSize failed:%w", err)
   }
   method := make([]byte, methodSize)
   _, err = io.ReadFull(reader, method)
   if err != nil {
      return fmt.Errorf("read method failed:%w", err)
   }

   // +----+--------+
   // |VER | METHOD |
   // +----+--------+
   // | 1  |   1    |
   // +----+--------+
   _, err = conn.Write([]byte{socks5Ver, 0x00})
   if err != nil {
      return fmt.Errorf("write failed:%w", err)
   }
   return nil
}

func connect(reader *bufio.Reader, conn net.Conn) (err error) {
   // +----+-----+-------+------+----------+----------+
   // |VER | CMD |  RSV  | ATYP | DST.ADDR | DST.PORT |
   // +----+-----+-------+------+----------+----------+
   // | 1  |  1  | X'00' |  1   | Variable |    2     |
   // +----+-----+-------+------+----------+----------+
   // VER 版本号，socks5的值为0x05
   // CMD 0x01表示CONNECT请求
   // RSV 保留字段，值为0x00
   // ATYP 目标地址类型，DST.ADDR的数据对应这个字段的类型。
   //   0x01表示IPv4地址，DST.ADDR为4个字节
   //   0x03表示域名，DST.ADDR是一个可变长度的域名
   // DST.ADDR 一个可变长度的值
   // DST.PORT 目标端口，固定2个字节

   buf := make([]byte, 4)
   _, err = io.ReadFull(reader, buf)
   if err != nil {
      return fmt.Errorf("read header failed:%w", err)
   }
   ver, cmd, atyp := buf[0], buf[1], buf[3]
   if ver != socks5Ver {
      return fmt.Errorf("not supported ver:%v", ver)
   }
   if cmd != cmdBind {
      return fmt.Errorf("not supported cmd:%v", cmd)
   }
   addr := ""
   switch atyp {
   case atypeIPV4:
      _, err = io.ReadFull(reader, buf)
      if err != nil {
         return fmt.Errorf("read atyp failed:%w", err)
      }
      addr = fmt.Sprintf("%d.%d.%d.%d", buf[0], buf[1], buf[2], buf[3])
   case atypeHOST:
      hostSize, err := reader.ReadByte()
      if err != nil {
         return fmt.Errorf("read hostSize failed:%w", err)
      }
      host := make([]byte, hostSize)
      _, err = io.ReadFull(reader, host)
      if err != nil {
         return fmt.Errorf("read host failed:%w", err)
      }
      addr = string(host)
   case atypeIPV6:
      return errors.New("IPv6: no supported yet")
   default:
      return errors.New("invalid atyp")
   }
   _, err = io.ReadFull(reader, buf[:2])
   if err != nil {
      return fmt.Errorf("read port failed:%w", err)
   }
   port := binary.BigEndian.Uint16(buf[:2])

   dest, err := net.Dial("tcp", fmt.Sprintf("%v:%v", addr, port))
   if err != nil {
      return fmt.Errorf("dial dst failed:%w", err)
   }
   defer dest.Close()
   log.Println("dial", addr, port)

   // +----+-----+-------+------+----------+----------+
   // |VER | REP |  RSV  | ATYP | BND.ADDR | BND.PORT |
   // +----+-----+-------+------+----------+----------+
   // | 1  |  1  | X'00' |  1   | Variable |    2     |
   // +----+-----+-------+------+----------+----------+
   // VER socks版本，这里为0x05
   // REP Relay field,内容取值如下 X’00’ succeeded
   // RSV 保留字段
   // ATYPE 地址类型
   // BND.ADDR 服务绑定的地址
   // BND.PORT 服务绑定的端口DST.PORT
   _, err = conn.Write([]byte{0x05, 0x00, 0x00, 0x01, 0, 0, 0, 0, 0, 0})
   if err != nil {
      return fmt.Errorf("write failed: %w", err)
   }
   ctx, cancel := context.WithCancel(context.Background())
   defer cancel()

   go func() {
      _, _ = io.Copy(dest, reader)
      cancel()
   }()
   go func() {
      _, _ = io.Copy(conn, dest)
      cancel()
   }()

   <-ctx.Done()
   return nil
}