英文:
simple static server who return static files in rotation for every request
问题
你好！以下是你要翻译的内容：
我有一个用Go语言编写的简单服务器：
package mainimport ("net/http")func main() {http.Handle("/", http.FileServer(http.Dir("./static")))http.ListenAndServe(":3000", nil)}
我想添加一个新的功能：
每次GET请求/rotate时，服务器从/static文件夹中返回一个旋转的文件内容。
例如，在/static文件夹中存在7个文件，对于每个请求，服务器返回：file1，file2，file3...
我该如何在Go中实现这个功能？
英文:
i have this simple server writed in golang :
package mainimport ("net/http")func main() {http.Handle("/", http.FileServer(http.Dir("./static")))http.ListenAndServe(":3000", nil)}
I want add new function :
every request GET /rotate return one file content in rotation from /static folder.
for example in /static folder exist 7 file, for every request server return : file1, file2, file3 ...
How i can do this in go ?
答案1
得分: 0
以下是一个简单的服务器，可以帮助你开始实现你的目标。关于实现的一些注意事项：
- 文件名只在程序启动时加载一次。如果文件在程序运行时消失，当它在轮换中出现时，服务器将返回404错误。
- 我们需要使用锁（在这种情况下是通过
sync.Mutex）来确保每个请求在自己的Go协程中运行。
package mainimport ("flag""net/http""os""path/filepath""sync")func main() {dir := flag.String("dir", ".", "directory of files to serve")flag.Parse()f, err := os.Open(*dir)if err != nil {panic(err)}files, err := f.Readdir(0)if err != nil {panic(err)}filenames := make([]string, 0, len(files))for _, file := range files {if !file.IsDir() {filenames = append(filenames, file.Name())}}var (idxLock sync.Mutexidx int)http.HandleFunc("/rotate", func(w http.ResponseWriter, r *http.Request) {if len(filenames) == 0 {http.NotFound(w, r)return}idxLock.Lock()i := idxidx++if idx >= len(filenames) {idx = 0}idxLock.Unlock()http.ServeFile(w, r, filepath.Join(*dir, filenames[i]))})if err := http.ListenAndServe(":3000", nil); err != nil {panic(err)}}
希望对你有帮助！
英文:
Below is a simple server that should get you started toward your goal. A couple of things to note about the implementation:
- The file names are loaded only once during program startup. If a file disappears while the program is running, the server will return a 404 when it comes up in the rotation.
- We need to use locking (in this case, via
sync.Mutex) as each request will run in its own go routine.
<!-- -->
package mainimport ("flag""net/http""os""path/filepath""sync")func main() {dir := flag.String("dir", ".", "directory of files to serve")flag.Parse()f, err := os.Open(*dir)if err != nil {panic(err)}files, err := f.Readdir(0)if err != nil {panic(err)}filenames := make([]string, 0, len(files))for _, file := range files {if !file.IsDir() {filenames = append(filenames, file.Name())}}var (idxLock sync.Mutexidx int)http.HandleFunc("/rotate", func(w http.ResponseWriter, r *http.Request) {if len(filenames) == 0 {http.NotFound(w, r)return}idxLock.Lock()i := idxidx++if idx >= len(filenames) {idx = 0}idxLock.Unlock()http.ServeFile(w, r, filepath.Join(*dir, filenames[i]))})if err := http.ListenAndServe(":3000", nil); err != nil {panic(err)}}
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