如何用Golang开发一个短链接服务 使用map内存存储实现

var shortToLong = make(map[string]string)
var longToShort = make(map[string]string)

func generateShortKey(id int) string {
    const base62 = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"
    result := ""
    for id > 0 {
        id--
        result = string(base62[id%62]) + result
        id /= 62
    }
    return result
}

var counter = 1

func shortenHandler(w http.ResponseWriter, r *http.Request) {
    longURL := r.URL.Query().Get("url")
    if longURL == "" {
        http.Error(w, "Missing 'url' parameter", http.StatusBadRequest)
        return
    }

    if short, exists := longToShort[longURL]; exists {
        fmt.Fprintf(w, "Short URL: http://localhost:8080/%s\n", short)
        return
    }

    short := generateShortKey(counter)
    counter++

    shortToLong[short] = longURL
    longToShort[longURL] = short

    fmt.Fprintf(w, "Short URL: http://localhost:8080/%s\n", short)
}

func redirectHandler(w http.ResponseWriter, r *http.Request) {
    parts := strings.Split(r.URL.Path, "/")
    if len(parts) < 2 || parts[1] == "" {
        http.Error(w, "Invalid short URL", http.StatusBadRequest)
        return
    }

    key := parts[1]
    if longURL, exists := shortToLong[key]; exists {
        http.Redirect(w, r, longURL, http.StatusFound)
    } else {
        http.NotFound(w, r)
    }
}

func main() {
    http.HandleFunc("/shorten", shortenHandler)
    http.HandleFunc("/", redirectHandler)

    fmt.Println("Starting server at :8080")
    if err := http.ListenAndServe(":8080", nil); err != nil {
        log.Fatal(err)
    }
}