HTTP编程

概述

Web工作原理

请求包和响应包

客户端 --请求包-> 服务器
客户端 <-响应包-- 服务器

http请求包格式

监听请求

package main

import (
    "fmt"
    "net"
)

func main(){
    // 监听
    listener, err := net.Listen("tcp", ":8000")
    if err!=nil{
        fmt.Println("Listen err = ", err)
        return
    }

    // 阻塞，等待用户的连接
    conn, err1 := listener.Accept()
    if err1 != nil {
        fmt.Println("Accept err1 = ", err1)
        return
    }

    defer conn.Close()

    // 接收客户端的数据
    buf := make([]byte, 1024*4)
    n, err2 := conn.Read(buf)
    if n==0 {
        fmt.Println("Accept err2 = ", err2)
        return
    }

    fmt.Printf("#####\n%v######", string(buf[:n]))
}

请求报文内容

#####
GET / HTTP/1.1
Host: 127.0.0.1:8000
Connection: keep-alive
Cache-Control: max-age=0
Upgrade-Insecure-Requests: 1
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_1) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/79.0.3945.130 Safari/537.36
Sec-Fetch-User: ?1
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,image/apng,*/*;q=0.8,application/signed-exchange;v=b3;q=0.9
Sec-Fetch-Site: none
Sec-Fetch-Mode: navigate
Accept-Encoding: gzip, deflate, br
Accept-Language: zh-CN,zh;q=0.9,en;q=0.8

######%

服务器监听响应

package main
import(
    "fmt"
    "net/http"
)

// w:给客户端回复数据
// r:读取客户端发送的数据
func myHander(w http.ResponseWriter, r *http.Request){
    fmt.Fprintln(w, "hello world")
}

// 服务端编写业务逻辑处理程序
func main(){
    // 注册处理函数，有用户连接自动调用指定的处理函数
    http.HandleFunc("/go", myHander) // 注册处理程序，回调函数

    // 监听绑定，在指定地址监听，开启一个http
    http.ListenAndServe("127.0.0.1:8000", nil)
}

输出响应内容

package main

import (
    "fmt"
    "net"
)

func main(){
    // 主动连接服务器
    conn, err := net.Dial("tcp", ":8000")
    if err != nil {
        fmt.Println("dial err = ", err)
        return 
    }

    defer conn.Close()

    requestBuf := "GET /go HTTP/1.1\r\nHost: 127.0.0.1:8000\r\nConnection: keep-alive\r\nCache-Control: max-age=0\r\nUpgrade-Insecure-Requests: 1\r\nUser-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_1) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/79.0.3945.130 Safari/537.36\r\nSec-Fetch-User: ?1\r\nAccept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,image/apng,*/*;q=0.8,application/signed-exchange;v=b3;q=0.9\r\nSec-Fetch-Site: none\r\nSec-Fetch-Mode: navigate\r\nAccept-Encoding: gzip, deflate, br\r\nAccept-Language: zh-CN,zh;q=0.9,en;q=0.8\r\n\r\n"
    // 先发请求包，服务器才会回响应包
    conn.Write([]byte(requestBuf))

    // 接收服务器回复的响应包
    buf := make([]byte, 1024*4)
    n, err1 := conn.Read(buf)
    if n == 0 {
        fmt.Println("Read err = ", err1)
        return 
    }

    // 打印响应报文
    fmt.Printf("####\n%v####", string(buf[:n]))
}

响应报文内容

####
HTTP/1.1 200 OK
Date: Sat, 15 Feb 2020 09:18:14 GMT
Content-Length: 12
Content-Type: text/plain; charset=utf-8

hello world
####%

响应失败

####
HTTP/1.1 404 Not Found
Content-Type: text/plain; charset=utf-8
X-Content-Type-Options: nosniff
Date: Sat, 15 Feb 2020 09:19:33 GMT
Content-Length: 19

404 page not found
####%

获取客户端一些信息

// w:给客户端回复数据
// req:读取客户端发送的数据
func HandConn(w http.ResponseWriter, req *http.Request) {
    fmt.Println("req.Method = ", req.Method)
    fmt.Println("req.URL = ", req.URL)
    fmt.Println("req.Header = ", req.Header)
    fmt.Println("req.Body = ", req.Body)
    w.Write([]byte("hello go")) // 给客户端回复数据
}

http客户端编程

package main
import (
    "fmt"
    "net/http"
)

func main(){
    resp, err := http.Get("http://127.0.0.1:8000")
    if err != nil {
        fmt.Println("http.Get err = ", err)
        return 
    }

    defer resp.Body.Close()

    fmt.Println("Status = ", resp.Status)
    fmt.Println("StatusCode = ", resp.StatusCode)
    fmt.Println("Header = ", resp.Header)
    // fmt.Println("Body = ", resp.Body)
    
    buf := make([]byte, 4*1024)
    var tmp string

    for{
        n, err := resp.Body.Read(buf)
        if n == 0 {
            fmt.Println("read err = ", err)
            break
        }

        tmp += string(buf[:n])
    }

    fmt.Println("tmp = ", tmp)
}