多线程分片下载

app/wails/pkg/sdk/downloader/downloader.go

@@ -166,7 +166,7 @@ func (d *Downloader) Run() error {
 	fByte := make([]byte, d.FileSize)
 
 	if exists(path) {
-		tmpFile, err = os.OpenFile(path, os.O_RDWR, 0)
+		tmpFile, err = os.OpenFile(path, os.O_RDWR|os.O_TRUNC|os.O_CREATE, 0)
 		if err != nil {
 			return err
 		}