Golang基礎庫之net/http

Go語言內置的net/http包十分的優秀，提供了HTTP客戶端和服務端的實現。

net/http介紹

Go語言內置的net/http包提供了HTTP客戶端和服務端的實現。

HTTP協議

超文本傳輸協議（HTTP，HyperText Transfer Protocol)是互聯網上應用最為廣泛的一種網絡傳輸協議，所有的WWW文件都必須遵守這個標准。設計HTTP最初的目的是為了提供一種發布和接收HTML頁面的方法。

HTTP客戶端

基本的HTTP/HTTPS請求

Get、Head、Post和PostForm函數發出HTTP/HTTPS請求。

resp, err := http.Get("http://example.com/")
...
resp, err := http.Post("http://example.com/upload", "image/jpeg", &buf)
...
resp, err := http.PostForm("http://example.com/form",
    url.Values{"key": {"Value"}, "id": {"123"}})

程序在使用完response后必須關閉回復的主體。

resp, err := http.Get("http://example.com/")
if err != nil {
    // handle error
}
defer resp.Body.Close()
body, err := ioutil.ReadAll(resp.Body)
// ...

 

 

[GET]

package main

import (
    "fmt"
    "io/ioutil"
    "net/http"
)

func main() {
    resp, err := http.Get("https://www.liwenzhou.com/")
    if err != nil {
        fmt.Printf("get failed, err:%v\n", err)
        return
    }
    defer resp.Body.Close()
    body, err := ioutil.ReadAll(resp.Body)
    if err != nil {
        fmt.Printf("read from resp.Body failed, err:%v\n", err)
        return
    }
    fmt.Print(string(body))
}

帶參數:

參數需要使用到net/url來處理

func main() {
    apiUrl := "http://127.0.0.1:9090/get"
    // URL param
    data := url.Values{}
    data.Set("name", "mi")
    data.Set("age", "18")
    u, err := url.ParseRequestURI(apiUrl)
    if err != nil {
        fmt.Printf("parse url requestUrl failed, err:%v\n", err)
    }
    u.RawQuery = data.Encode() // URL encode
    fmt.Println(u.String())
    resp, err := http.Get(u.String())
    if err != nil {
        fmt.Printf("post failed, err:%v\n", err)
        return
    }
    defer resp.Body.Close()
    b, err := ioutil.ReadAll(resp.Body)
    if err != nil {
        fmt.Printf("get resp failed, err:%v\n", err)
        return
    }
    fmt.Println(string(b))
}

帶header頭部信息:

import (
    "net/http"
)

url := "https://b959e645-00ae-4bc3-8a55-7224d08b1d91.mock.pstmn.io/user/1"

req, _ := http.NewRequest("GET", url, nil)

req.Header.Add("Authorization", "xxxx")

response, err := http.DefaultClient.Do(req)

 

 

 

 

對應server端:

func getHandler(w http.ResponseWriter, r *http.Request) {
    defer r.Body.Close()
    data := r.URL.Query()
    fmt.Println(data.Get("name"))
    fmt.Println(data.Get("age"))
    answer := `{"status": "ok"}`
    w.Write([]byte(answer))
}

 

[POST]

package main

import (
    "fmt"
    "io/ioutil"
    "net/http"
    "strings"
)

// net/http post demo

func main() {
    url := "http://127.0.0.1:9090/post"
    // 表單數據
    //contentType := "application/x-www-form-urlencoded"
    //data := "name=mi&age=18"
    // json
    contentType := "application/json"
    data := `{"name":"mi","age":18}`
    resp, err := http.Post(url, contentType, strings.NewReader(data))
    if err != nil {
        fmt.Printf("post failed, err:%v\n", err)
        return
    }
    defer resp.Body.Close()
    b, err := ioutil.ReadAll(resp.Body)
    if err != nil {
        fmt.Printf("get resp failed, err:%v\n", err)
        return
    }
    fmt.Println(string(b))
}

PostForm方式

func httpPostForm() {
    resp, err := http.PostForm("http://www.01happy.com/demo/accept.php",

        url.Values{"key": {"Value"}, "id": {"123"}})

    if err != nil {

        // handle error

    }

    defer resp.Body.Close()

    body, err := ioutil.ReadAll(resp.Body)

    if err != nil {

        // handle error

    }

    fmt.Println(string(body))

}

json:

func testPostJson() {
    data := make(map[string]interface{})
    data["site"] = "www.360.com"
    data["name"] = "xxx"
    bytesData, _ := json.Marshal(data)
    resp, _ := http.Post("http://httpbin.org/post", "application/json", bytes.NewReader(bytesData))
    body, _ := ioutil.ReadAll(resp.Body)
    fmt.Println(string(body))
}

 

 

 

帶有headers參數

func httpDo() {

    client := &http.Client{}

    req, err := http.NewRequest("POST", "http://www.01happy.com/demo/accept.php", strings.NewReader("name=cjb"))

    if err != nil {

        // handle error
    }

    req.Header.Set("Content-Type", "application/x-www-form-urlencoded")

    req.Header.Set("Cookie", "name=anny")

    resp, err := client.Do(req)

    defer resp.Body.Close()
    body, err := ioutil.ReadAll(resp.Body)

    if err != nil {

        // handle error
    }
    fmt.Println(string(body))
}

 

 

 

 

 

對應server端:

func postHandler(w http.ResponseWriter, r *http.Request) {
    defer r.Body.Close()
    // 1. 請求類型是application/x-www-form-urlencoded時解析form數據
    r.ParseForm()
    fmt.Println(r.PostForm) // 打印form數據
    fmt.Println(r.PostForm.Get("name"), r.PostForm.Get("age"))
    // 2. 請求類型是application/json時從r.Body讀取數據
    b, err := ioutil.ReadAll(r.Body)
    if err != nil {
        fmt.Printf("read request.Body failed, err:%v\n", err)
        return
    }
    fmt.Println(string(b))
    answer := `{"status": "ok"}`
    w.Write([]byte(answer))
}

 

自定義Client

要管理HTTP客戶端的頭域、重定向策略和其他設置，創建一個Client：

client := &http.Client{
    CheckRedirect: redirectPolicyFunc,
}
resp, err := client.Get("http://example.com")
// ...
req, err := http.NewRequest("GET", "http://example.com", nil)
// ...
req.Header.Add("If-None-Match", `W/"wyzzy"`)
resp, err := client.Do(req)

自定義Transport

要管理代理、TLS配置、keep-alive、壓縮和其他設置，創建一個Transport：

tr := &http.Transport{
    TLSClientConfig:    &tls.Config{RootCAs: pool},
    DisableCompression: true,
}
client := &http.Client{Transport: tr}
resp, err := client.Get("https://example.com")

Client和Transport類型都可以安全的被多個goroutine同時使用。出於效率考慮，應該一次建立、盡量重用。

 

 

服務端

默認的Server

ListenAndServe使用指定的監聽地址和處理器啟動一個HTTP服務端。處理器參數通常是nil，這表示采用包變量DefaultServeMux作為處理器。

Handle和HandleFunc函數可以向DefaultServeMux添加處理器。

http.Handle("/foo", fooHandler)
http.HandleFunc("/bar", func(w http.ResponseWriter, r *http.Request) {
    fmt.Fprintf(w, "Hello, %q", html.EscapeString(r.URL.Path))
})
log.Fatal(http.ListenAndServe(":8080", nil))

默認的Server示例

使用Go語言中的net/http包來編寫一個簡單的接收HTTP請求的Server端示例，net/http包是對net包的進一步封裝，專門用來處理HTTP協議的數據。具體的代碼如下：

package main

import (
    "fmt"
    "net/http"
)

func sayHello(w http.ResponseWriter, r *http.Request) {
    fmt.Fprintln(w, "Hello shanghai！")
}

func main() {
    http.HandleFunc("/", sayHello)
    err := http.ListenAndServe(":9090", nil)
    if err != nil {
        fmt.Printf("http server failed, err:%v\n", err)
        return
    }
}

將上面的代碼編譯之后執行，打開你電腦上的瀏覽器在地址欄輸入127.0.0.1:9090回車

 

自定義Server

要管理服務端的行為，可以創建一個自定義的Server：

s := &http.Server{
    Addr:           ":8080",
    Handler:        myHandler,
    ReadTimeout:    10 * time.Second,
    WriteTimeout:   10 * time.Second,
    MaxHeaderBytes: 1 << 20,
}
log.Fatal(s.ListenAndServe())

 

 

 demo:

package main

import (
    "encoding/json"
    _"encoding/json"
    "fmt"
    "io/ioutil"
    "net/http"
    "net/url"
    "strings"
)

var (
    api = "http://xxxxx.com"
    token = "9adf92861"
)

type Result struct {
    Code int `json:"code"`
    Msg string `json:"msg"`
}

type Resp struct {
    Code string `json:"code"`
    Msg string `json:"msg"`
}


func wechatUrlHandle(w http.ResponseWriter, r *http.Request){
    // 獲取鏈接地址
    var wechatUrl string
    values := r.URL.Query()
    wechatUrl = values.Get("url")
    // 驗證URL的正確性
    targetUrl, err := url.ParseRequestURI(wechatUrl)
    if err != nil {
        fmt.Printf("parse url failed, err:%v\n", err)
    }
    fmt.Printf(fmt.Sprintf("url: %v", targetUrl))

    // 拼接參數發起請求
    data := fmt.Sprintf("token=%s&url=%s", token, targetUrl.String())

    headers := "application/x-www-form-urlencoded"
    res, err := http.Post(api, headers, strings.NewReader(data))
    if err != nil {
        fmt.Printf("post failed, err: %v\n", err)
        return
    }

    // 關閉請求資源
    defer res.Body.Close()
    body, err := ioutil.ReadAll(res.Body)
    if err != nil{
        fmt.Fprintf(w, fmt.Sprintf("get resp failed. err: %v\n", err))
        return
    }
    
    var info Result
    var ress Resp
    w.Header().Set("Content-Type", "application/json")
    if err := json.Unmarshal(body, &info); err == nil {
        fmt.Println(info.Code, info.Msg)
        ress.Code = "200"
        ress.Msg = "Success"
        t, _ := json.Marshal(ress)
        w.Write(t)
    }else{
        ress.Code = "200"
        ress.Msg = "failure"
        t, _ := json.Marshal(ress)
        fmt.Println("err: ", err)
        w.Write(t)
    }
}

func main() {
    
    http.HandleFunc("/wechat/url", wechatUrlHandle)
    err := http.ListenAndServe(":9090", nil)  // 處理器參數一般未nil
    if err != nil {
        fmt.Printf("Http server failed. err: %v\n", err)
        return
    }

}