OSS对象储存android开发进行下载到本地文件时异步操作失效

// 构造下载文件请求。
// 依次填写Bucket名称（例如examplebucket）和Object完整路径（例如exampledir/exampleobject.txt）。Object完整路径中不能包含Bucket名称。
GetObjectRequest get = new GetObjectRequest("examplebucket", "exporter1.xls");

oss.asyncGetObject(get, new OSSCompletedCallback<GetObjectRequest, GetObjectResult>() {
    @Override
    public void onSuccess(GetObjectRequest request, GetObjectResult result) {
// 开始读取数据。
        long length = result.getContentLength();
        if (length > 0) {
            byte[] buffer = new byte[(int) length];
            int readCount = 0;
            while (readCount < length) {
                try{
                    readCount += result.getObjectContent().read(buffer, readCount, (int) length - readCount);
                }catch (Exception e){
                    OSSLog.logInfo(e.toString());
                }
            }
    // 将下载后的文件存放在指定的本地路径，例如D:\\localpath\\exampleobject.jpg。
            try {
                FileOutputStream fout = new FileOutputStream("download_filePath");
                fout.write(buffer);
                fout.close();
            } catch (Exception e) {
                OSSLog.logInfo(e.toString());
            }
        }
    }

    @Override
    public void onFailure(GetObjectRequest request, ClientException clientException,
                          ServiceException serviceException)  {

    }
});