1. package main
    3. import (
    4.     "TestProject/filelistingserver/filelisting"
    5.     "log"
    6.     "net/http"
    7.     "os"
    8. )
    10. type appHandler func(writer http.ResponseWriter, request *http.Request) error
    12. func errWrapper(handler appHandler) func(http.ResponseWriter, *http.Request) {
    13.     return func(writer http.ResponseWriter, request *http.Request) {
    14.         defer func() {
    15.             if r := recover(); r != nil {
    16.                 log.Printf("Panic: %v", r)
    17.                 http.Error(writer,
    18.                     http.StatusText(http.StatusInternalServerError),
    19.                     http.StatusInternalServerError)
    20.             }
    21.         }()
    23.         err := handler(writer, request)
    25.         if err != nil {
    26.             log.Printf("Error occurred handling request: %s", err.Error())
    27.             if userErr, ok := err.(userError); ok {
    28.                 http.Error(writer,
    29.                     userErr.Message(),
    30.                     http.StatusBadRequest)
    31.                 return
    32.             }
    33.             code := http.StatusOK
    34.             switch {
    35.             case os.IsNotExist(err):
    36.                 code = http.StatusNotFound
    37.             case os.IsPermission(err):
    38.                 code = http.StatusForbidden
    39.             default:
    40.                 code = http.StatusInternalServerError
    41.             }
    42.             http.Error(
    43.                 writer,
    44.                 http.StatusText(code),
    45.                 code)
    46.         }
    47.     }
    48. }
    50. type userError interface {
    51.     error
    52.     Message() string
    53. }
    55. func main() {
    56.     http.HandleFunc("/", errWrapper(filelisting.HandleFileList))
    58.     err := http.ListenAndServe(":8888", nil)
    59.     if err != nil {
    60.         panic(err)
    61.     }
    62. }
    1. package filelisting
    3. import (
    4.     "fmt"
    5.     "io/ioutil"
    6.     "net/http"
    7.     "os"
    8.     "strings"
    9. )
    11. const prefix = "/list/"
    13. type userError string
    15. func (e userError) Error() string {
    16.     return e.Message()
    17. }
    19. func (e userError) Message() string {
    20.     return string(e)
    21. }
    23. func HandleFileList(writer http.ResponseWriter, request *http.Request) error {
    24.     if strings.Index(request.URL.Path, prefix) != 0 {
    25.         return userError(fmt.Sprintf("path %s must start "+
    26.             "with %s",
    27.             request.URL.Path, prefix))
    28.     }
    29.     path := request.URL.Path[len(prefix):]
    30.     file, err := os.Open(path)
    31.     if err != nil {
    32.         return err
    33.     }
    34.     defer file.Close()
    36.     all, err := ioutil.ReadAll(file)
    37.     if err != nil {
    38.         return err
    39.     }
    41.     writer.Write(all)
    42.     return nil
    43. }