无法在 Android 备份服务中实现 onBackup()

如何解决无法在 Android 备份服务中实现 onBackup()

这个 page 给出了代码：

// Get the oldState input stream
FileInputStream instream = new FileInputStream(oldState.getFileDescriptor());
DataInputStream in = new DataInputStream(instream);

try {
    // Get the last modified timestamp from the state file and data file
    long stateModified = in.readLong();
    long fileModified = dataFile.lastModified();

    if (stateModified != fileModified) {
        // The file has been modified,so do a backup
        // Or the time on the device changed,so be safe and do a backup
    } else {
        // Don't back up because the file hasn't changed
        return;
    }
} catch (IOException e) {
    // Unable to read state file... be safe and do a backup
}

当我通过日志测试时：

Log.i(Const.TAG,"\n" +
                "stateModified:" + stateModified + "\n" +
                "fileModified:" + fileModified
        );

它给了我如此荒谬的数字：

stateModified:1729382258125336577

fileModified:1617703865000

那么，进行这种比较的意义何在： if (stateModified != fileModified) 其中数字差异很大。

我尝试使用 bmgr 实用程序执行多次备份/恢复，但情况没有改变。