Golang基础库之net/http

Go语言内置的net/http包十分的优秀，提供了HTTP客户端和服务端的实现。

net/http介绍

Go语言内置的net/http包提供了HTTP客户端和服务端的实现。

HTTP协议

超文本传输协议（HTTP，HyperText Transfer Protocol)是互联网上应用最为广泛的一种网络传输协议，所有的WWW文件都必须遵守这个标准。设计HTTP最初的目的是为了提供一种发布和接收HTML页面的方法。

HTTP客户端

基本的HTTP/HTTPS请求

Get、Head、Post和PostForm函数发出HTTP/HTTPS请求。

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后必须关闭回复的主体。

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))
}

带参数:

参数需要使用到net/url来处理

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))
}

带header头部信息:

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)

对应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"
    // 表单数据
    //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))
}

带有headers参数

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))
}

对应server端:

func postHandler(w http.ResponseWriter, r *http.Request) {
    defer r.Body.Close()
    // 1. 请求类型是application/x-www-form-urlencoded时解析form数据
    r.ParseForm()
    fmt.Println(r.PostForm) // 打印form数据
    fmt.Println(r.PostForm.Get("name"), r.PostForm.Get("age"))
    // 2. 请求类型是application/json时从r.Body读取数据
    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))
}

自定义Client

要管理HTTP客户端的头域、重定向策略和其他设置，创建一个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)

自定义Transport

要管理代理、TLS配置、keep-alive、压缩和其他设置，创建一个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类型都可以安全的被多个goroutine同时使用。出于效率考虑，应该一次建立、尽量重用。

服务端

默认的Server

ListenAndServe使用指定的监听地址和处理器启动一个HTTP服务端。处理器参数通常是nil，这表示采用包变量DefaultServeMux作为处理器。

Handle和HandleFunc函数可以向DefaultServeMux添加处理器。

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))

默认的Server示例

使用Go语言中的net/http包来编写一个简单的接收HTTP请求的Server端示例，net/http包是对net包的进一步封装，专门用来处理HTTP协议的数据。具体的代码如下：

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
    }
}

将上面的代码编译之后执行，打开你电脑上的浏览器在地址栏输入127.0.0.1:9090回车

自定义Server

要管理服务端的行为，可以创建一个自定义的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){
    // 获取链接地址
    var wechatUrl string
    values := r.URL.Query()
    wechatUrl = values.Get("url")
    // 验证URL的正确性
    targetUrl, err := url.ParseRequestURI(wechatUrl)
    if err != nil {
        fmt.Printf("parse url failed, err:%v\n", err)
    }
    fmt.Printf(fmt.Sprintf("url: %v", targetUrl))

    // 拼接参数发起请求
    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
    }

    // 关闭请求资源
    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)  // 处理器参数一般未nil
    if err != nil {
        fmt.Printf("Http server failed. err: %v\n", err)
        return
    }

}