[TOC]
概述
go 的http包是作为其他web framework的基础，web框架（echo, gin, chi, martini）都基于http拓展而来。但是目前官方网站也没给出很好的例子解释。目前找到比较全面介绍的参考如下： https://cryptic.io/go-http/
http server
四个重要概念
- http.Handler: 所有设计都基于该接口，路由对应的处理函数，包含*Request 和 RresponseWriter, 处理请求，返回response。
- 接口： ServeHTTP(ResponseWriter, *Request)
- http.HandlerFunc：将普通的函数和匿名函数转化成http.Handler接口，快速创建Handler避免每次需要struct实现
- http.ServeMux httpr的默认路由管理器，匹配请求的endpoint，调用对应的handler，该类型也实现了http.Handler。前面的两个是基础实现，针对不同endpoint做不同的操作，就是ServeMux的功能。 http的路由器可以扩展实现，第三方web framework基于Handler接口，实现与ServeMux相同的功能。ServerMux有如下两个方法，做的事情一样，接受不同的参数：
- ServerMux. HandleFunc(endpoint, HandlerFunc)
- ServerMux.Handle(endpoint, Handler)
- Middleware chains: 基于http.Handle组成一条链。第三方的web framework一般也实现了middleware chains的管理如[Alice]https://github.com/justinas/alice)。中间键的实现的两种方式
- HandlerFunc: 用一个普通函数接受Handler参数，返回一个HandlerFunc
- Handler: 用一个struct保存Handler实例，实现Handler接口
timeout
参考： https://blog.cloudflare.com/the-complete-guide-to-golang-net-http-timeouts/
image.png
- ReadTimeout: accept到read body或accept 到read header
- WriteTimeout: read body 到完成write response
- IdleTimeout： keepalive 保活时间
http client
client
http client 应用层设置。it is safe for concurrent use.
功能
- headers
- redirect policy
- cookies
- timeout: 请求的超时间，包括：连接，重定向，读取response body
transport
- 传输与通信层设置
- http 底层操作
- it is safe for concurrent use
功能
-
RoundTripper 接口： 执行一系列操作(HTTP transaction)，获取response。 该接口必须支持concurrent use.
- 可以用于mock，返回特定的reponse，用于测试
- proxies
- TLS configuration
- TLSHandshakeTimeout: TLS handshake timeouts
- keep-alives
- DisableKeepAlives
- MaxIdleConnsPerHost: 每个主机最大的keepalive idle 连接. 为0时采用DefaultMaxIdleConnsPerHost(为2)
- IdleConnTimeout: keepalive 连接保持的时间
- compression
- basic auth
Dialer
包含一些有关连接的设置
- Timeout
- Deadline
- KeepAlive:
- 0:禁止使用KeepAlive
-
>0: 保持keepalive的时间
client timeout
image.png
- 注意事项： 没有可以设置发送整个request 的时间限制，server也没有设置发送整个response的时间限制，可以通过Context实现：https://play.golang.org/p/kvqwVd39oai
- 部分timeout已经随着新版本消失
client middleware
/*
the middleware example of http client
*/
package main
import (
"net/http"
"log"
"fmt"
"os"
)
// TransportFunc implements the RountTripper interface
type TransportFunc func(*http.Request) (*http.Response, error)
// RoundTrip just calls the original function
func (tf TransportFunc) RoundTrip(r *http.Request) (*http.Response, error) {
return tf(r)
}
// RoundTripperDecorator is a convenience function to represent our
// middleware inner function
type RoundTripperDecorator func(http.RoundTripper) http.RoundTripper
// Decorate is a helper to wrap all the middleware
// eg: Decorate( &http.Transport, mw1, mw2, mw3)
// mw1 --> mw2 --> ... --> http.RoundTripper
func Decorate(t http.RoundTripper, rts ...RoundTripperDecorator) http.RoundTripper {
if len(rts) == 0 {
return t
}
lastPos := len(rts) - 1
decorated := rts[lastPos](t)
rts[lastPos] = nil
for i := lastPos - 1; i >= 0; i-- {
decorated = rts[i](decorated)
}
return decorated
}
// Logger is one of our 'middleware' decorators
func Logger(l *log.Logger) RoundTripperDecorator {
return func(c http.RoundTripper) http.RoundTripper {
return TransportFunc(func(r *http.Request) (*http.Response, error) {
fmt.Println("this is logger")
// start := time.Now()
// l.Printf("started request to %s at %s", r.URL, start.Format("2006-01-02 15:04:05"))
resp, err := c.RoundTrip(r)
// l.Printf("completed request to %s in %s", r.URL, time.Since(start))
return resp, err
})
}
}
// BasicAuth is another of our 'middleware' decorators
func BasicAuth(username, password string) RoundTripperDecorator {
return func(c http.RoundTripper) http.RoundTripper {
return TransportFunc(func(r *http.Request) (*http.Response, error) {
fmt.Println("this is Basic Auth")
r.SetBasicAuth(username, password)
resp, err := c.RoundTrip(r)
return resp, err
})
}
}
func main() {
c := http.Client{}
t := Decorate(
&http.Transport{},
Logger(log.New(os.Stdout, "", 0)),
BasicAuth("username", "password"),
)
c.Transport = t
resp, err := c.Get("https://www.google.com")
if err != nil {
fmt.Println(err)
}
fmt.Println("Response code:", resp.StatusCode)
}
best tips for http client
- 合理设置Client.Timeout(请求超时时间)： time.Second * N
- 合理设置Transport.MaxIdleConnsPerHost
参考：
