Finish most of Lock things.

rest/download/download.go

@@ -362,3 +362,37 @@ func DownloadFile(
 	}
 
 }
+
+
+
+// 从指定的url下载一个文件。参考：https://golangcode.com/download-a-file-from-a-url/
+func HttpDownloadFile(filepath string, url string) (int64, error) {
+
+	// Create the file
+	out, err := os.Create(filepath)
+	if err != nil {
+		return 0, err
+	}
+	defer func() {
+		e := out.Close()
+		PanicError(e)
+	}()
+
+	// Get the data
+	resp, err := http.Get(url)
+	if err != nil {
+		return 0, err
+	}
+	defer func() {
+		e := resp.Body.Close()
+		PanicError(e)
+	}()
+
+	// Write the body to file
+	size, err := io.Copy(out, resp.Body)
+	if err != nil {
+		return 0, err
+	}
+
+	return size, nil
+}