Add a customized httpx Router

Author: aclisp

router/filehandler.go

@@ -0,0 +1,82 @@
+package router
+
+import (
+	"net/http"
+	"strings"
+	"sync"
+)
+
+// fileHandler returns a middleware that serves files from the given file system.
+func fileHandler(path string, fs http.FileSystem) func(http.HandlerFunc) http.HandlerFunc {
+	fileServer := http.FileServer(fs)
+	pathWithoutTrailSlash := ensureNoTrailingSlash(path)
+	canServe := createServeChecker(path, fs)
+
+	return func(next http.HandlerFunc) http.HandlerFunc {
+		return func(w http.ResponseWriter, r *http.Request) {
+			if canServe(r) {
+				r.URL.Path = r.URL.Path[len(pathWithoutTrailSlash):]
+				// no-cache allows caches to store a response but requires them to revalidate it before reuse.
+				w.Header().Set("Cache-Control", "no-cache")
+				w.Header().Set("Vary", "Origin, Cache-Control")
+				fileServer.ServeHTTP(w, r)
+			} else {
+				next(w, r)
+			}
+		}
+	}
+}
+
+func createFileChecker(fs http.FileSystem) func(string) bool {
+	var lock sync.RWMutex
+	fileChecker := make(map[string]bool)
+
+	return func(path string) bool {
+		lock.RLock()
+		exist, ok := fileChecker[path]
+		lock.RUnlock()
+		if ok {
+			return exist
+		}
+
+		lock.Lock()
+		defer lock.Unlock()
+
+		file, err := fs.Open(path)
+		exist = err == nil
+		fileChecker[path] = exist
+		if err != nil {
+			return false
+		}
+
+		_ = file.Close()
+		return true
+	}
+}
+
+func createServeChecker(path string, fs http.FileSystem) func(r *http.Request) bool {
+	pathWithTrailSlash := ensureTrailingSlash(path)
+	fileChecker := createFileChecker(fs)
+
+	return func(r *http.Request) bool {
+		return r.Method == http.MethodGet &&
+			strings.HasPrefix(r.URL.Path, pathWithTrailSlash) &&
+			fileChecker(r.URL.Path[len(pathWithTrailSlash):])
+	}
+}
+
+func ensureTrailingSlash(path string) string {
+	if strings.HasSuffix(path, "/") {
+		return path
+	}
+
+	return path + "/"
+}
+
+func ensureNoTrailingSlash(path string) string {
+	if strings.HasSuffix(path, "/") {
+		return path[:len(path)-1]
+	}
+
+	return path
+}

router/router.go

@@ -0,0 +1,31 @@
+package router
+
+import (
+	"net/http"
+
+	"github.com/zeromicro/go-zero/rest"
+	"github.com/zeromicro/go-zero/rest/httpx"
+	"github.com/zeromicro/go-zero/rest/router"
+)
+
+// Router returns a customized httpx Router
+func New(path string, fs http.FileSystem) httpx.Router {
+	rt := router.NewRouter()
+	return newFileServingRouter(rt, path, fs)
+}
+
+type fileServingRouter struct {
+	httpx.Router
+	middleware rest.Middleware
+}
+
+func newFileServingRouter(router httpx.Router, path string, fs http.FileSystem) httpx.Router {
+	return &fileServingRouter{
+		Router:     router,
+		middleware: fileHandler(path, fs),
+	}
+}
+
+func (f *fileServingRouter) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	f.middleware(f.Router.ServeHTTP)(w, r)
+}