在USB大容量存储模式连接（通过电话），当SD卡数据有时没有看到PC [英] SD card data sometimes NOT seen on PC when connected in USB mass storage mode (via phone)

问题描述

可能重复：结果
   SD卡的内容存在，但不能看到他们

手机插入SD卡运行Linux内核（2.6.31）。

Phone running Linux Kernel(2.6.31) with SD card inserted.

[问题]当数据被写入到SD卡（写入系统调用）的写入成功返回。然而，当卡（通过电话），为在计算机上的大容量存储设备被访问时，该数据是没有看到

[ISSUE] When data is written to SD card (write syscall) the write returns successfully. However, when the card (via phone) is accessed as a mass storage device on PC, the data is not seen.

只有在物理上取出卡并重新插入，然后访问它在PC上作为大容量存储装置将显示该被写入的数据。
写入数据后试图FSYNC（）。它仍然不会显示。

Only after physically removing the card and reinserting it and then accessing it on PC as a mass storage device will show the data that was written. Tried fsync() after writing the data. Still it wont show.

是内核维护数据写入SD卡前缓存？如果是这样，我怎么确保它被刷新到SD卡？

Is the kernel maintaining a cache before writing the data to SD card? If so, how do I make sure it is flushed to the SD card?

推荐答案

您的问题是的 SD卡的内容存在，但不能看到他们 - 从MTP接口返回的计算机显示内容

Your problem is an exact duplicate of SDCard content exist but cant see them - the PC is displaying the content as returned from the MTP interface.

存根code做你需要做的是什么文件显示：

Stub code to do what you need to make the file appear:

进口：

import android.media.MediaScannerConnection;
import android.os.Environment;
import android.util.Log;
import java.io.File;

存根code：

File f = new File(Environment.getExternalStorageDirectory().getPath() + "/hello_nurse.txt");
if (! f.exists()) {
    try {
        f.createNewFile();
        String[] files = new String[1];
        files[0] = Environment.getExternalStorageDirectory().getPath() + "/hello_nurse.txt";
        String[] mimes = new String[1];
        mimes[0] = "text/plain";
        MediaScannerConnection.scanFile(getApplicationContext(), files, mimes, null);
    } catch (Exception ex) {
        Log.e("SD Create", "Failed to create file", ex);
        return;
    }
} else {
    Log.e("SD Create", "File is already present");
}

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