执行下载操作时，添加监听，allSize 为 null

[chenchaoyun0]

`new ProgressListener() {
@OverRide
public void start() {
System.out.println("下载开始");
}

@Override
public void progress(long progressSize,Long allSize) {

    System.out.println("已下载 " + progressSize + " 总大小" + allSize);
}

@Override
public void finish() {
    System.out.println("下载结束");
}

}`

allSize 拿到是null，对象存储是阿里云OSS