在Golang中实现GitHub徽章

Question

我之前已经问过这个问题而没有得到满意的答复,所以这次我试着更具体一点.

我想在golang中实现一个服务器,它以svg的形式输出动态状态更新.(想想"构建传递/失败"GitHub徽章.)目的是应该能够在GitHub自述文件中嵌入到服务器地址的链接,并且自述文件应根据服务器状态自动更新.

这是我提出的golang代码,但它似乎不适用于GitHub积极缓存.我是否需要添加更多Cache-Control标头？我需要添加ETag吗？

我正在使用以下内容将图像嵌入GitHub自述文件中.

[![Mine](http://58dcd0b5.ngrok.com/view)]()

理想情况下,我希望GitHub自述文件每次加载时都会更改图像 - 在两个图像之间翻转"正确"/"错误".(这只是概念证明.)

package main

import (
    "log"
    "net/http"
    _ "time"
)
var mymap map[string][]byte

var state bool = false


func viewHandler(w http.ResponseWriter, r *http.Request) {
    log.Printf("State %v", state)
    state = !state
    w.Header().Set("Content-Type", "image/svg+xml")
    w.Header().Set("Cache-Control", "no-cache, no-store, must-revalidate")
    if state {
        w.Write(mymap["correct"])
    } else {
        w.Write(mymap["wrong"])
    }
}

func main() {
    mymap = make(map[string][]byte)
    mymap["correct"] = []byte(`<svg xmlns="http://www.w3.org/2000/svg" width="104" height="20"><linearGradient id="b" x2="0" y2="100%"><stop offset="0" stop-color="#bbb" stop-opacity=".1"/><stop offset="1" stop-opacity=".1"/></linearGradient><mask id="a"><rect width="104" height="20" rx="3" fill="#fff"/></mask><g mask="url(#a)"><path fill="#555" d="M0 0h54v20H0z"/><path fill="#4c1" d="M54 0h50v20H54z"/><path fill="url(#b)" d="M0 0h104v20H0z"/></g><g fill="#fff" text-anchor="middle" font-family="DejaVu Sans,Verdana,Geneva,sans-serif" font-size="11"><text x="28" y="15" fill="#010101" fill-opacity=".3">solution</text><text x="28" y="14">solution</text><text x="78" y="15" fill="#010101" fill-opacity=".3">correct</text><text x="78" y="14">correct</text></g></svg>`)
    mymap["wrong"] = []byte(`<svg xmlns="http://www.w3.org/2000/svg" width="99" height="20"><linearGradient id="b" x2="0" y2="100%"><stop offset="0" stop-color="#bbb" stop-opacity=".1"/><stop offset="1" stop-opacity=".1"/></linearGradient><mask id="a"><rect width="99" height="20" rx="3" fill="#fff"/></mask><g mask="url(#a)"><path fill="#555" d="M0 0h54v20H0z"/><path fill="#e05d44" d="M54 0h45v20H54z"/><path fill="url(#b)" d="M0 0h99v20H0z"/></g><g fill="#fff" text-anchor="middle" font-family="DejaVu Sans,Verdana,Geneva,sans-serif" font-size="11"><text x="28" y="15" fill="#010101" fill-opacity=".3">solution</text><text x="28" y="14">solution</text><text x="75.5" y="15" fill="#010101" fill-opacity=".3">wrong</text><text x="75.5" y="14">wrong</text></g></svg>`)

    mux := http.NewServeMux()
    mux.HandleFunc("/view", viewHandler)
    http.ListenAndServe(":8085", mux)
}

Answer 1

在提交到shields.io server之后，我对上面的代码进行了以下更改，现在它可以工作了。

w.Header().Set("Date", date)
w.Header().Set("Expires", date)

为了完整起见（如果有人想尝试一下），这里是完整的代码。（也在GitHub上。）

package main

import (
    "log"
    "net/http"
    "time"
)

var mymap map[string][]byte

var state bool = false

func viewHandler(w http.ResponseWriter, r *http.Request) {
    date := time.Now().Format(http.TimeFormat)
    log.Printf("%v", date)
    log.Printf("State %v", state)
    state = !state
    w.Header().Set("Content-Type", "image/svg+xml")
    w.Header().Set("Cache-Control", "no-cache, no-store, must-revalidate")
    w.Header().Set("Date", date)
    w.Header().Set("Expires", date)
    if state {
        w.Write(mymap["correct"])
    } else {
        w.Write(mymap["wrong"])
    }
}

func main() {
    mymap = make(map[string][]byte)
    mymap["correct"] = []byte(`<svg xmlns="http://www.w3.org/2000/svg" width="104" height="20"><linearGradient id="b" x2="0" y2="100%"><stop offset="0" stop-color="#bbb" stop-opacity=".1"/><stop offset="1" stop-opacity=".1"/></linearGradient><mask id="a"><rect width="104" height="20" rx="3" fill="#fff"/></mask><g mask="url(#a)"><path fill="#555" d="M0 0h54v20H0z"/><path fill="#4c1" d="M54 0h50v20H54z"/><path fill="url(#b)" d="M0 0h104v20H0z"/></g><g fill="#fff" text-anchor="middle" font-family="DejaVu Sans,Verdana,Geneva,sans-serif" font-size="11"><text x="28" y="15" fill="#010101" fill-opacity=".3">solution</text><text x="28" y="14">solution</text><text x="78" y="15" fill="#010101" fill-opacity=".3">correct</text><text x="78" y="14">correct</text></g></svg>`)
    mymap["wrong"] = []byte(`<svg xmlns="http://www.w3.org/2000/svg" width="99" height="20"><linearGradient id="b" x2="0" y2="100%"><stop offset="0" stop-color="#bbb" stop-opacity=".1"/><stop offset="1" stop-opacity=".1"/></linearGradient><mask id="a"><rect width="99" height="20" rx="3" fill="#fff"/></mask><g mask="url(#a)"><path fill="#555" d="M0 0h54v20H0z"/><path fill="#e05d44" d="M54 0h45v20H54z"/><path fill="url(#b)" d="M0 0h99v20H0z"/></g><g fill="#fff" text-anchor="middle" font-family="DejaVu Sans,Verdana,Geneva,sans-serif" font-size="11"><text x="28" y="15" fill="#010101" fill-opacity=".3">solution</text><text x="28" y="14">solution</text><text x="75.5" y="15" fill="#010101" fill-opacity=".3">wrong</text><text x="75.5" y="14">wrong</text></g></svg>`)

    mux := http.NewServeMux()
    mux.HandleFunc("/view", viewHandler)
    log.Println("Server started. Listening on 8085...")
    http.ListenAndServe(":8085", mux)
}