diff --git a/conf/wide.go b/conf/wide.go
index a297c4c..813a55c 100644
--- a/conf/wide.go
+++ b/conf/wide.go
@@ -219,20 +219,20 @@ func (*conf) GetExecutableInGOBIN(executable string) string {
 		// $GOPATH/bin/$GOOS_$GOARCH/executable
 		ret := gopath + PathSeparator + "bin" + PathSeparator +
 			os.Getenv("GOOS") + "_" + os.Getenv("GOARCH") + PathSeparator + executable
-		if isExist(ret) {
+		if util.File.IsExist(ret) {
 			return ret
 		}
 
 		// $GOPATH/bin/{runtime.GOOS}_{runtime.GOARCH}/executable
 		ret = gopath + PathSeparator + "bin" + PathSeparator +
 			runtime.GOOS + "_" + runtime.GOARCH + PathSeparator + executable
-		if isExist(ret) {
+		if util.File.IsExist(ret) {
 			return ret
 		}
 
 		// $GOPATH/bin/executable
 		ret = gopath + PathSeparator + "bin" + PathSeparator + executable
-		if isExist(ret) {
+		if util.File.IsExist(ret) {
 			return ret
 		}
 	}
@@ -390,7 +390,7 @@ func CreateWorkspaceDir(path string) {
 
 // createDir creates a directory on the path if it not exists.
 func createDir(path string) {
-	if !isExist(path) {
+	if !util.File.IsExist(path) {
 		if err := os.MkdirAll(path, 0775); nil != err {
 			glog.Error(err)
 
@@ -400,10 +400,3 @@ func createDir(path string) {
 		glog.V(7).Infof("Created a directory [%s]", path)
 	}
 }
-
-// isExist determines whether the file spcified by the given filename is exists.
-func isExist(filename string) bool {
-	_, err := os.Stat(filename)
-
-	return err == nil || os.IsExist(err)
-}
diff --git a/file/files.go b/file/files.go
index b88a153..82977e6 100644
--- a/file/files.go
+++ b/file/files.go
@@ -54,8 +54,8 @@ type Snippet struct {
 
 // GetFiles handles request of constructing user workspace file tree.
 //
-// The Go API source code package ($GOROOT/src/pkg) also as a child node,
-// so that users can easily view the Go API source code.
+// The Go API source code package also as a child node,
+// so that users can easily view the Go API source code in filre tree.
 func GetFiles(w http.ResponseWriter, r *http.Request) {
 	data := map[string]interface{}{"succ": true}
 	defer util.RetJSON(w, r, data)
@@ -84,6 +84,7 @@ func GetFiles(w http.ResponseWriter, r *http.Request) {
 
 	// construct Go API node
 	apiPath := runtime.GOROOT() + conf.PathSeparator + "src" + conf.PathSeparator + "pkg"
+
 	apiNode := FileNode{Name: "Go API", Path: apiPath, IconSkin: "ico-ztree-dir-api ", Type: "d",
 		Creatable: false, Removable: false, FileNodes: []*FileNode{}}
 
@@ -123,7 +124,7 @@ func GetFile(w http.ResponseWriter, r *http.Request) {
 
 	extension := filepath.Ext(path)
 
-	if isImg(extension) {
+	if util.File.IsImg(extension) {
 		// image file will be open in a browser tab
 
 		data["mode"] = "img"
@@ -143,7 +144,7 @@ func GetFile(w http.ResponseWriter, r *http.Request) {
 
 	content := string(buf)
 
-	if isBinary(content) {
+	if util.File.IsBinary(content) {
 		data["succ"] = false
 		data["msg"] = "Can't open a binary file :("
 	} else {
@@ -318,7 +319,7 @@ func Find(w http.ResponseWriter, r *http.Request) {
 	userWorkspace := conf.Wide.GetUserWorkspace(username)
 	workspaces := filepath.SplitList(userWorkspace)
 
-	if "" != path && !isDir(path) {
+	if "" != path && !util.File.IsDir(path) {
 		path = filepath.Dir(path)
 	}
 
@@ -441,7 +442,7 @@ func listFiles(dirname string) []string {
 //
 // Refers to the zTree document for CSS class names.
 func getIconSkin(filenameExtension string) string {
-	if isImg(filenameExtension) {
+	if util.File.IsImg(filenameExtension) {
 		return "ico-ztree-img "
 	}
 
@@ -660,7 +661,7 @@ func searchInFile(path string, text string) []*Snippet {
 	}
 
 	content := string(bytes)
-	if isBinary(content) {
+	if util.File.IsBinary(content) {
 		return ret
 	}
 
@@ -679,41 +680,6 @@ func searchInFile(path string, text string) []*Snippet {
 	return ret
 }
 
-// isBinary determines whether the specified content is a binary file content.
-func isBinary(content string) bool {
-	for _, b := range content {
-		if 0 == b {
-			return true
-		}
-	}
-
-	return false
-}
-
-// isImg determines whether the specified extension is a image.
-func isImg(extension string) bool {
-	ext := strings.ToLower(extension)
-
-	switch ext {
-	case ".jpg", ".jpeg", ".bmp", ".gif", ".png", ".svg", ".ico":
-		return true
-	default:
-		return false
-	}
-}
-
-// isDir determines whether the specified path is a directory.
-func isDir(path string) bool {
-	fio, err := os.Lstat(path)
-	if nil != err {
-		glog.Warningf("Determines whether [%s] is a directory failed: [%v]", path, err)
-
-		return false
-	}
-
-	return fio.IsDir()
-}
-
 // GetUsre gets the user the specified path belongs to. Returns nil if not found.
 func GetUsre(path string) *conf.User {
 	for _, user := range conf.Wide.Users {
diff --git a/util/file.go b/util/file.go
new file mode 100644
index 0000000..dc4d086
--- /dev/null
+++ b/util/file.go
@@ -0,0 +1,55 @@
+package util
+
+import (
+	"os"
+	"strings"
+
+	"github.com/golang/glog"
+)
+
+type myfile struct{}
+
+// File utilities.
+var File = myfile{}
+
+// IsExist determines whether the file spcified by the given path is exists.
+func (*myfile) IsExist(path string) bool {
+	_, err := os.Stat(path)
+
+	return err == nil || os.IsExist(err)
+}
+
+// IsBinary determines whether the specified content is a binary file content.
+func (*myfile) IsBinary(content string) bool {
+	for _, b := range content {
+		if 0 == b {
+			return true
+		}
+	}
+
+	return false
+}
+
+// IsImg determines whether the specified extension is a image.
+func (*myfile) IsImg(extension string) bool {
+	ext := strings.ToLower(extension)
+
+	switch ext {
+	case ".jpg", ".jpeg", ".bmp", ".gif", ".png", ".svg", ".ico":
+		return true
+	default:
+		return false
+	}
+}
+
+// IsDir determines whether the specified path is a directory.
+func (*myfile) IsDir(path string) bool {
+	fio, err := os.Lstat(path)
+	if nil != err {
+		glog.Warningf("Determines whether [%s] is a directory failed: [%v]", path, err)
+
+		return false
+	}
+
+	return fio.IsDir()
+}